2014
Team 14: Expedition Camper
Engineering 340: Senior Design Project
Calvin College
DESIGN REPORT
INFORMATION TECHNOLOGY
1
© 2014, Team 14 and Calvin College
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Duplication of any portion of this document may only be done with team consent.
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Executive Summary
This report details the research and design of the Expedition Camper. The team designed this camper to be
taken off-road over very rugged terrain. The most unique aspect of this project was that the camper was
designed to also function as a boat. The camper’s complex design and robust construction allow it to be
pulled over large obstacles encountered on off-road trails, as well as to be removed from the trailer and
placed into a pond or lake so that it can traverse across water. Team Expedition Camper, otherwise known
as Team 14, chose this project for their senior capstone project. Completion of this report is also
accompanied by a working prototype, tested for off-road travel and functionality as a boat and camper.
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Contents
Executive Summary ................................................................................................................................ 2
Table of Tables........................................................................................................................................ 6
Table of Figures ...................................................................................................................................... 7
1 Introduction ........................................................................................................................................ 9
1.1
The Project............................................................................................................................... 9
1.2
Design Norms .......................................................................................................................... 9
1.2.1
Transparency .................................................................................................................... 9
1.2.2
Integrity ........................................................................................................................... 9
1.2.3
Trust................................................................................................................................. 9
1.3
The Class ................................................................................................................................. 9
2 Project Management ......................................................................................................................... 10
2.1
The Team ............................................................................................................................... 10
2.1.1
2.2
Schedule ................................................................................................................................ 11
2.2.1
Task List ........................................................................................................................ 11
2.2.2
Gantt Chart ..................................................................................................................... 12
2.3
3
Team Roles .................................................................................................................... 10
Finance .................................................................................................................................. 13
Project Breakdown ........................................................................................................................ 13
3.1
Project Description ................................................................................................................. 13
3.1.1
Camper........................................................................................................................... 13
3.1.2
Trailer ............................................................................................................................ 14
3.2 Objectives .................................................................................................................................... 14
3.2.1 Dual Capability ..................................................................................................................... 14
3.2.2 Lightweight ........................................................................................................................... 14
3.2.3 Durable ................................................................................................................................. 14
3.2.4 Maneuverable ....................................................................................................................... 14
3.2.5 User Friendly ........................................................................................................................ 15
3.2.6 Aesthetically Pleasing ........................................................................................................... 15
4 Project Specifications ....................................................................................................................... 15
4.1
Camper .................................................................................................................................. 15
4.1.1
Size ................................................................................................................................ 15
4.1.2
Shape ............................................................................................................................. 16
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4.1.3
Weight ........................................................................................................................... 16
4.1.4
Durability ....................................................................................................................... 17
4.1.5
Materials ........................................................................................................................ 17
4.1.6
Aesthetics ....................................................................................................................... 19
4.1.7
Usability......................................................................................................................... 19
4.2
Trailer .................................................................................................................................... 19
4.2.1
Materials ........................................................................................................................ 20
4.2.2
Maneuverability ............................................................................................................. 20
4.2.3
Height Variation ............................................................................................................. 20
5 Design Process ................................................................................................................................. 20
5.1
Camper .................................................................................................................................. 20
5.1.1
Stability .......................................................................................................................... 20
5.1.2
Launch Parameters ......................................................................................................... 24
5.1.3
Boat Frame ..................................................................................................................... 27
5.1.4
Front Wall Section.......................................................................................................... 30
5.1.5
Soft Top and Mount........................................................................................................ 31
5.1.6
Motor and Motor Mount ................................................................................................. 33
5.2
Trailer .................................................................................................................................... 35
5.2.1
Trailer Frame.................................................................................................................. 35
5.2.2
Hitch .............................................................................................................................. 36
5.2.3
Suspension ..................................................................................................................... 38
5.2.4
Tie Down Points ............................................................................................................. 42
5.2.5
Straps ............................................................................................................................. 42
5.2.6
Trailer Jacks ................................................................................................................... 43
5.3
Finite Element Analysis ......................................................................................................... 43
5.3.1
Camper/Boat FEA .......................................................................................................... 44
5.3.2
Trailer FEA .................................................................................................................... 46
6 Testing ............................................................................................................................................. 49
6.1
Safety..................................................................................................................................... 49
6.2
Initial Testing ......................................................................................................................... 50
6.2.1
Drop Testing .................................................................................................................. 50
6.2.2
Launch Testing ............................................................................................................... 50
6.2.3
Stability Testing ............................................................................................................. 50
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6.3
Modifications ......................................................................................................................... 50
7 Business Plan ................................................................................................................................... 50
7.1
Market Competition ............................................................................................................... 50
7.2
Break-even Analysis .............................................................................................................. 51
8 Conclusion ....................................................................................................................................... 52
9 Acknowledgements .......................................................................................................................... 54
10 Bibliography ................................................................................................................................... 55
Appendix A: EES Calculations ............................................................................................................. 56
Appendix B: Design Drawings ............................................................................................................. 58
Appendix C: Budget .............................................................................................................................. 64
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Table of Tables
Table 1: Anticipated tasks for design and build of the Expedition Camper. ............................................ 11
Table 2: Cost estimate. .......................................................................................................................... 13
Table 3: Market research for the Expedition Camper.............................................................................. 16
Table 4: Tow capacities of typical off-road vehicles. .............................................................................. 17
Table 5: Properties of common boat hull materials. ............................................................................... 18
Table 6: Component weights. ................................................................................................................ 21
Table 7: Weight calculations.................................................................................................................. 24
Table 8: Off-road campers and their base purchase prices. ..................................................................... 51
Table 9: Cost per camper and annual fixed costs. ................................................................................... 51
Table 10: Break Even Analysis for Expedition Camper. ......................................................................... 52
Table 11: Complete Project Budget ....................................................................................................... 64
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Table of Figures
Figure 1: The team – Mitch Hopkins, Jordan Veltema, Nathan Hiemstra, Jordan Mast. .......................... 10
Figure 2: Gantt chart showing an anticipated schedule for the team. ....................................................... 12
Figure 3: Angle of list as a function of the bottom width of the boat. ...................................................... 22
Figure 4: Distance boat lists into the water as a function of width of the boat. ........................................ 23
Figure 5: Distance Camper will sink into water based on weight. ........................................................... 25
Figure 6: Camper height dimensions for launch parameter reference. .................................................... 26
Figure 7: Dimensions and calculations to find height difference between points A and B. ...................... 27
Figure 8: Approximate dimensions for Jeep-styled tub portion of camper............................................... 28
Figure 9: Approximate boat hull dimensions. ......................................................................................... 29
Figure 10: Frame of the camper. ............................................................................................................ 30
Figure 11: Front wall in camper frame. .................................................................................................. 31
Figure 12: Approximate top dimensions. ............................................................................................... 32
Figure 13: Approximate roll bar dimensions. ......................................................................................... 33
Figure 14: Motor mount on back of camper frame ................................................................................. 35
Figure 15: 501 with a 510 off-road trailer hitch by Lock N’ Roll ............................................................ 36
Figure 16: Solid works model of three axis hitch.................................................................................... 37
Figure 17: Leaf spring suspension system. ............................................................................................. 38
Figure 19: Stress on leaf spring as a function of drop height. .................................................................. 39
Figure 20: Air bag suspension system. ................................................................................................... 40
Figure 21: Arm for air bag suspension. .................................................................................................. 41
Figure 22: Stacker jacks and scissors jacks. ........................................................................................... 43
Figure 23: Boat stress FEA. ................................................................................................................... 44
Figure 24: Boat deflection FEA. ............................................................................................................ 45
Figure 25: Final camper/boat FEA model. ............................................................................................. 46
Figure 26: Trailer stress FEA. ................................................................................................................ 47
Figure 27: Trailer displacement FEA. .................................................................................................... 47
Figure 28: Airbag mounting bracket FEA simulation. ............................................................................ 48
Figure 29: Stress FEA of final trailer design. ......................................................................................... 49
Figure 30: Preliminary design drawing. .................................................................................................. 58
Figure 31: Side view, top down. ............................................................................................................. 59
Figure 32: Side view, top up ................................................................................................................... 59
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Figure 33: Front View ............................................................................................................................ 60
Figure 34: Top View ............................................................................................................................... 60
Figure 35: Boat removed from trailer..................................................................................................... 61
Figure 36: Colored side view, top down. ................................................................................................ 62
Figure 37: Colored side view, top up. ..................................................................................................... 62
Figure 38: Colored perspective view showing entrance.......................................................................... 63
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1 Introduction
1.1
The Project
Team 14, Expedition Camper, set out to design and build a recreational unit that functions as a camper and
a boat. The design allows for the camper to be removed from the trailer, placed into the water, and driven
away as a boat. The product was aimed at outdoor, wilderness enthusiasts who enjoy the beaten trail rather
than the paved road. The camper is lightweight and durable, allowing it to travel on rugged terrain. The
camper is sleek, aesthetically pleasing, and aerodynamic. The camper is also easily detachable from the
trailer and has the ability to move through water. Optimization calculations were used to determine the best
combination of all engineering aspects.
1.2
Design Norms
As Calvin engineers in training, our team strove to uphold Christian values in the design of the camper. In
order to uphold these Christian values, the following design norms were implemented.
1.2.1 Transparency
In order for the Expedition Camper to appeal to the greatest number of people, it was designed so that the
customer would be able to learn how to use it rather easily. The team ensured that the design of the
Expedition Camper was not only user friendly, but also that it held in high regard the safety and well-being
of the end user.
1.2.2 Integrity
In order for the Expedition Camper to fulfill the design norm of integrity, it was designed to be intuitive
and easy to operate. The design was simple enough for the common user to understand how it works.
1.2.3 Trust
The Expedition Camper itself was a good concept, but in order to meet the design norm of trust, it also had
to endure sustained use. The Expedition Camper is designed to be strong and reliable, ensuring that the user
will feel completely safe when using the product.
1.3
The Class
This project spanned the entire two semesters of the team’s senior year in Calvin College’s engineering
program. The senior capstone project class challenged the students in the program to use all the knowledge
they had gained to tackle a real-world project. With the knowledge and experience the team had gained
over their years of coursework, the team created something unique and fun. Using gained knowledge, the
team performed detailed studies and calculations to determine the best way to design and build the product.
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By the end of the class, the team was able to build a product that they showcased on senior design night.
The team’s ability to solve complex problems was well represented by the end product.
2 Project Management
2.1
The Team
Team Expedition Camper consisted of Nathan Hiemstra, Mitchell Hopkins, Jordan Mast, and Jordan
Veltema. Each member studied in the mechanical concentration of engineering at Calvin College. Jordan
Veltema’s background in manufacturing, as well as experience with automotive body repair, proved to be
helpful during the project. Both Jordan Mast and Nathan Hiemstra worked at Innotec and were able to use
their experience with manufacturing equipment and machine design. Mitchell Hopkins’ experience with
the use of design software, through his work at Progressive Surface, also made it easier to create design
drawings. The team members are shown in Figure 1.
Figure 1: The team – Mitch Hopkins, Jordan Veltema, Nathan Hiemstra, Jordan Mast.
2.1.1 Team Roles
Nathan Hiemstra – Design and Manufacturing
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Nathan had a large amount of knowledge with regard to manufacturing, as well as skills in sheet metal
work, welding, and fabrication of various metal products. Nathan also has vast knowledge with regard to
off-road vehicles. He was in charge of managing the construction of the prototype and worked closely with
Mitchell to develop a proper prototype design that allowed for ease of manufacturing. This also included
allocating people and resources to find all of the necessary parts, perform fabrication, and develop
subassemblies to build the prototype.
Jordan Mast – Website Design/ Team Management
Jordan has the most knowledge with respect to website design and team management, as well as a strong
knowledge of metal fabrication. He was in charge of creating and keeping the website up to date, as well
as being heavily involved with the manufacturing of the prototype. Furthermore, Jordan was tasked with
managing the team ensuring that they stay on schedule and within budget.
Jordan Veltema – Documentation and Manufacturing
Jordan had excellent editing and documentation skills, as well as an expansive knowledge about cars and
other vehicles. He was in charge of making the final edits on all written documents done collectively by the
team, and also is assisted in the design and building of the prototype.
Mitchell Hopkins – Design and Analysis
Mitchell has a vast knowledge of computer software design. His extensive experience with the SolidWorks
software package allowed him to construct a detailed 3D model of the prototype. He was in charge of
creating a complete model of the project as well as performing Finite Element Analysis of various parts or
subassemblies. He worked closely with the entire team in order to ensure that manufacturing of all nonpurchased parts went smoothly.
2.2
Schedule
2.2.1 Task List
The following table shows the task list for the year of what was to be completed for the project. In order to
finish the project, every item on the task chart had to be addressed in some way or manner. Many of these
tasks are addressed in more detail in later sections of the report.
Table 1: Anticipated tasks for design and build of the Expedition Camper.
TASK NAME
DESCRIPTION
PROJECT MANAGEMENT
Determine goals and estimate time for each task.
GANTT CHART
Schedule of events and tasks for the year.
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RESEARCH
Research necessary for all aspects of the design.
BUDGETING
Budgeting to determine the cost of the project.
BUDGET PROPOSAL
Finalize total budget.
CONCEPTUAL DRAWINGS
Preliminary drawings of end product.
DESIGN
Designing each component to meet engineering requirements.
FEA ANALYSIS
Perform computer simulations to test component strengths.
PPFS REPORT
Mid-year report stating the feasibility of the project.
MANUFACTURING
Final stages consist of the construction of the project.
TESTING
Testing will be done on the product.
FINAL REPORT
A final report will be issued on the website.
2.2.2 Gantt Chart
At the beginning of the year, the team put together a list of anticipated tasks that would need to be
completed. The task list is shown previously, in Table 1, and a Gantt Chart is shown below, in Figure 2,
indicating an approximation of how each task fits within the schedule of the year.
Figure 2: Gantt chart showing an anticipated schedule for the team.
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2.3
Finance
The following spreadsheet, Table 2, provides an estimation of project expenses required for building a
prototype of the Expedition Camper. This table shows an estimation of the team’s budget. However, over
the course of the project the team realized that they had underestimated the project cost. The final cost of
the project ended up being more than expected and a complete bill of materials with associated costs can
be found in Appendix E.
Table 2: Cost estimate.
STARTING BALANCE
$ 2,255.00
COMPONENTS
Cost
Remaining Balance
TRAILER & BOAT
$ 800.00
$ 1,455.00
TROLLING MOTOR
$ 250.00
$ 1,205.00
WOOD
$ 100.00
$ 1,105.00
ALUMINUM
$ 425.00
$ 680.00
STEEL
$ 200.00
$ 480.00
ELECTRICAL
$ 75.00
$ 405.00
AIR BAG SUSPENSION
$ 100.00
$ 305.00
MISC
$ 100.00
$ 205.00
CONTINGENCY
10%
RAW MATERIALS
ADDITIONAL
3
Project Breakdown
3.1
Project Description
The project was broken down into two main categories, the camper and the trailer. The camper section
discusses the aspects of the unit being used as a camper and a boat. The trailer section focuses on the
structural aspects of the trailer and on equipping it to be towed off-road.
3.1.1 Camper
The Expedition Camper was designed for one or two people. When it is being used on land as a camper, it
is attached to the trailer with tie-downs to ensure safety of the user while moving in and out of the camper.
The camper also provides enough room for proper sleeping accommodations in various types of weather.
When the soft-top is up, the interior of the camper is completely sealed from the outside keeping the bugs
and rain out. The clever design of the soft top and soft top mount allows the user to easily assemble for
shelter and disassemble for use on the water.
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The camper is also able to operate safely as a watercraft. The launch and retrieval of the Expedition Camper
is simple enough for one person to do on their own. The outboard motor is attached to a mount on the back
of the camper. When the camper is out on the water, it is stable enough for a person to move around without
struggling to stay balanced. The user can maneuver the Expedition Camper across the water with ease.
Operating the throttle and steering the motor is comfortable and straightforward.
3.1.2 Trailer
The trailer is designed and built to withstand any conditions that it will be required to face. The air bag
suspension allows for a 9.7 inch range of lift. This offers a way for the trailer to sit high when being towed
and lowered when launching the camper into the water. The trailer will undoubtedly experience a variety
of uneven pathways, but the multi-axial hitch greatly reduces the stresses in the hitch connection. The trailer
is built to be towed across any type of terrain that a Jeep or other off-road vehicle can travel across. The
trailer is also able to withstand weathering and impact from rocks and other rough terrain.
3.2 Objectives
3.2.1 Dual Capability
The main objective for this project was to design the camper to be capable of functioning as a camper and
a boat. Requirements for the camper aspect were that it could be used for sleeping accommodations and
could store various camping supplies. Requirements for the boat aspect were that it could be safely used to
travel on water.
3.2.2 Lightweight
An objective was set for the unit to be no more than 1500 pounds dry weight. This 1500 pounds comprises
the camper and the trailer. This objective was developed because the camper should be easy to tow off-road
by typical off-road vehicles, many of which do not have a very high towing capacity. Furthermore, by
designing the camper to be lightweight, it would be easier to launch and retrieve.
3.2.3 Durable
For the unit to be towed in off-road situations, it must be durable. An objective set for the durability of the
camper was that it must be able to survive a drop of up to 1 foot. A sudden drop of 1 foot would have large
impact stresses on the camper, and it must be durable enough to withstand these stresses.
3.2.4 Maneuverable
One requirement of the camper being used as a boat was that it must be able to travel through the water
with ease. This refers to a few different aspects such as how fast it can go, how easily it can be turned, and
how stable it is when traveling. A goal of a minimum of 5 mph was set for the speed. This objective was
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set because it was desired for the camper to be able to function as a boat, therefore, it must be able to
compete with other small boats in the areas of speed and stability.
3.2.5 User Friendly
For the camper to be used successfully, it must be user friendly. This applies to a variety of areas of the
camper both onshore and offshore. One aspect was that it must be easy to launch and retrieve the camper.
Furthermore, it must be easy to raise and lower the soft-top. On the water, the camper must be easy to use
for activities such as fishing and duck hunting.
3.2.6 Aesthetically Pleasing
A general objective for the camper was that it would be aesthetically pleasing. The team wanted to design
a camper that looks mostly like a camper, with the additional functionality of a boat. It was a goal for the
team to build a camper that looks well done and that draws the attention of people passing by.
4 Project Specifications
In designing an Expedition Camper, there were numerous factors that needed to be taken into account.
Because the Expedition Camper has the ability to function as both a camper and a boat, discussion of the
multifunctional aspects of the Expedition Camper were divided into two sections: those associated with the
camper portion and those associated with the trailer portion.
4.1
Camper
For the camper portion of the design, defined to be the bottom tub and the soft-top, important design factors
included size, shape, weight, materials, durability, aesthetics, and usability.
4.1.1 Size
The first factor researched was size. There were many different dimensions that were important in the
design of the Expedition Camper. The first group of dimensions that were determined describe the usable
space inside the camper. In order to determine acceptable interior camper dimensions, research was
performed with regard to different off-road campers currently on the market. Table 3 summarizes these
interior dimensions for three of the major off-road campers. From these benchmark examples, it was
determined that the interior of the camper should have a width of approximately 5 feet, a length of
approximately 8 feet, and a height of approximately 4 feet. Given these rough dimensions, several other
factors were used to determine more exact interior dimensions.
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4.1.2 Shape
Another important factor of the boat portion for the camper was the shape of the hull. While there were a
variety of boat hull shapes that could be used, such as pontoons, v-hull, or tri-hull, it was clear that a slight
V-shaped bottom best suites the functionality of the Expedition Camper. Unlike other boat bottom shapes,
the slight V-bottom provides a low profile. This was important for ground clearance when traversing over
rough, rocky, and uneven terrains. It was also important from an aesthetics point of view because it was
desired that the Expedition Camper be disguised as more of a camper than as a boat. Furthermore, a slight
V-bottom shape allowed for the Expedition Camper boat portion to be launched in more shallow waters
than any other hull shape would offer. This was an important aspect, which will be described more in later
sections, given that the camper would need to have the ability to launch without access to a ramp made
specifically for launching a boat.
4.1.3 Weight
Another important factor evaluated was the dry weight of the camper. The dry weight was defined to be
the weight of the camper without the weight that would be added from additional items such as water jugs,
gasoline cans, furnishings, baggage, tools, equipment, and so on. Research of the dry weights of other offroad campers currently on the market was again used in the determination of an acceptable dry weight for
the Expedition Camper being designed. These dry weights are included in Table 3 for the same three offroad campers used for dimension criteria. From these weights it was concluded that the camper should
have a dry weight of 1500 pounds, which is on the higher end of the examples provided. This was because
it was assumed that the additional boat functionality, not present in the benchmark examples, adds some
extra weight to the camper.
Table 3: Market research for the Expedition Camper.
TRAILER
MOBY1 XTR
1
SO-CAL TEARDROPS
LENGTH
WIDTH
HEIGHT
DRY WEIGHT
[IN]
[IN]
[IN]
[LBS.]
80
54 or 60
45
1,500
109.5
53
44.5
1,250
107
54
45
1,283
THE KRAWLER2
ADVENTURE TRAILERS
TEARDROP
3
1
http://moby1trailers.com/moby1-xtr/
http://www.socalteardrops.com/page.php?p=22
3
http://www.adventuretrailers.com/teardrop.html
2
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Furthermore, the dry and overall weight of the camper become important aspects when evaluated according
to the measure of the tow capacity of the typical off-road vehicle. Table 4 contains research with regard to
the tow capacity of several typical off-road vehicles. This research confirmed the maximum dry weight
decision of 1500 pounds and also set a requirement that the weight of the camper should not exceed 2000
pounds when fully loaded with all accessories.
Table 4: Tow capacities of typical off-road vehicles.
VEHICLE
TOW CAPACITY [LBS.]
JEEP WRANGLER (2 DOOR, 4 DOOR)4
TOYOTA FJ CRUISER
NISSAN FRONTIER
6
5
2,000 - 3,500
4,700
6,500
4.1.4 Durability
One of the key purposes for the design of the camper was that it should have great durability. The camper
and top are able to withstand the impact forces and heavy vibrations encountered during use in the harshest
of off-road environments. In order to achieve a design featuring a high level of durability, material
properties, in addition to overall structural design, were extremely important. Given that the boat portion
of the Expedition Camper was in the most susceptible position to be affected by the harsh environments
experienced in an off-road setting, material considerations are discussed in the following section of the
report.
4.1.5 Materials
Correct material selection was pivotally important due to the fact that the Expedition Camper was purposed
to be subjected to some of the harshest environmental conditions when put to use and must also meet the
weight limits the team set. Research revealed four potential candidates for material selection: wood,
fiberglass, aluminum, and steel for the framework of the camper. Additionally a removable material for the
roof was needed to make the camper more functional as a boat when in water.
4
http://www.jeep.com/en/2013/wrangler/capability/towing/
http://www.toyota.com/fjcruiser/features.html#!/exterior/4702/4703/4704
6
http://www.nissanusa.com/trucks/frontier
5
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In order for the end product to comply with the other design requirements, wood was quickly eliminated.
This was because the boat portion of the camper must be capable of withstanding harsh conditions of the
off-road environment, such as impact loads, abrasive contact, and constant vibrations. Not only would a
wooden hull be impractical for withstanding impacts and abrasion, it also would be susceptible to rattle
apart and therefore would develop leaks over time. Furthermore, development of a wood hull that can
withstand the conditions seen in an off-road environment would undoubtedly lead to a design that does not
fit within the weight constraints of the project.
An evaluation of the three remaining materials, fiberglass, aluminum, and steel, revealed that aluminum
was the optimal construction material for the hull of the camper. An aluminum hull best fit the requirements
of the project and was chosen for several different aspects. These include strength, weight, abrasive
resistance, and cost.
From a strength point of view, low carbon steel had the highest tensile strength, as shown in Table 5.
However, because a design criterion of the project was that it must be relatively lightweight, building the
camper hull from an extremely dense material, such as steel, most assuredly would have led to an
Expedition Camper that surpassed weight constraints. On the opposite end of the spectrum, fiberglass has
a relatively weak tensile strength. While a fiberglass hull could provide enough strength, the amount of
fiberglass needed to build the hull would result in an Expedition Camper that was heavier than desired. The
main interest from a design standpoint was the strength-to-weight ratio of the material. Because 5052
aluminum stands between fiberglass and steel with both tensile strength and density, it boasts the highest
strength-to-weight ratio. Therefore, aluminum was the best candidate for construction material from both
a strength and weight point of view.
Table 5: Properties of common boat hull materials. 7
MATERIAL
TENSILE STRENGTH
DENSITY [LBS./FT3]
STRENGTH/WEIGHT
[PSI]
RATIO
FIBERGLASS
18,000
95-100
180-189
LOW CARBON STEEL
58,000-68,000
470
123-145
5052 ALUMINUM
33,000
167
197
Not only did aluminum score high in the strength and weight categories, it also had several other favorable
properties with regard to abrasive resistance and weather-ability. Unlike fiberglass, it does not gouge or
scratch easily. These material properties were extremely desirable for the Expedition Camper, given that it
7
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19
would see the occasional brush of a tree branch or impact of a stone. Additionally, aluminum ranks high in
the category of weather-ability. Both steel and fiberglass are highly susceptible to deteriorate over time.
Steel corrodes quickly with the elements, while fiberglass blisters and delaminates. On the other hand, the
only concerns with aluminum were that it can develop cracks if cyclically loaded and not reinforced
properly and that it could develop corrosion when in contact with dissimilar metals. However, both of these
are easily remedied with care.
It is true that fiberglass boats are less expensive to produce in a long-run production environment. Once
the molds have been built for the boat, an easy, repeatable process could be used to mold multiple boat
hulls. However, the capital investment costs required for good, production quality molds are staggering.
With aluminum, there were no hefty up-front costs like this required.
Along with the aluminum framework a soft top was needed in order to enclose the camper. The team
determined that using a Jeep soft top would serve this purpose and be easily integrated with the design.
4.1.6 Aesthetics
The overall look and feel of the camper also played an influential role in the design. In order for the
Expedition Camper to be a competitive option for outdoor enthusiasts, the design needed to be aesthetically
pleasing. One of the largest groups of people for whom the Expedition Camper would appeal, would be
Jeep owners due to the Jeep’s extreme level of popularity in the off-road realm. Because of this fact, it was
decided that the Expedition Camper would do well to incorporate Jeep styling. Furthermore, with regard
to marketability, there was no Jeep-styled multipurpose off-road camper currently on the market. The
absence of similar products on the market provided a good opportunity for the Expedition Camper.
4.1.7 Usability
Another critical factor of the project, specifically with respect to the camper portion, was the ease of use.
This was especially true in its application with regard to the top of the camper. This was a crucial
requirement especially when the Expedition Camper was used in its boat function. The sides and roof of
the top are easily removable so they do not obscure the view of users when the camper is used in its boat
function. To achieve this transformable functionality, the sides and top of the camper were constructed from
a vinyl/cloth material so that they could be easily zipped out, rolled up, or folded down. This also allows
users to stand up inside when the Expedition Camper is being used as a boat.
4.2
Trailer
For the trailer portion of the design, important design factors included materials, maneuverability, and
height variation.
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4.2.1 Materials
The selection for materials of the trailer were based on similar criteria as the camper portion. The main
objective was that this trailer would take a lot of beating while being used off-road. In order to ensure the
trailer would handle high stresses during travel, 2 inch x 4 inch x 1/8 inch thick steel tubing was used for
the frame of the trailer and 2 inch x 3 inch x 1/8 inch thick steel tubing was used for the cross beams
supporting the camper portion. FEA models were used, and are explained in more detail later, to determine
if this material would be strong enough.
In order to attach the suspension system to the frame ¼ inch thick steel mounting plates were welded to the
trailer. These give the air bags a flat and strong surface to push against. Along with the suspension mounts,
brackets were made out of the same material for the shocks. The shocks keep the trailer from bouncing
around excessively.
Along with the ruggedness of the frame the team decided to include UHMW strips on the cross-support
beams to protect the bottom of the boat, as well as to allow it to be more easily removable. The friction
coefficient of UHMW is much lower than that of steel which is why sliding the boat on these strips makes
it easier to move on and off the trailer.
4.2.2 Maneuverability
Maneuverability was one other key aspect the team wanted to address. Because the Expedition Camper was
made for off-roading, maneuverability was key. Two key ways the team addressed this issue was through
a multi-axial hitch as well as an air bag suspension, which were covered in more detail in the proceeding
section. The multi-axial hitch allows for the trailer to move more independently from the vehicle towing it.
Because off-road terrain is so uneven, this was a great benefit to have while towing the Expedition Camper.
4.2.3 Height Variation
One of the more luxurious additions to the trailer was the use of an air bag suspension system, because the
camper would be launched in areas without a boat launch as well as travel over larger obstacles. The Airlift
Dominator D2600 air bags give an overall height variation of up to 9.7 inches. This addition gives the trailer
the ability to pass over large rocks as well as provide adjustability to sit low during the launch process.
5 Design Process
5.1
Camper
The team went through several different modifications throughout the design process of the camper.
5.1.1 Stability
One major hurdle in the design of the boat portion of the Expedition Camper was its stability on water.
Typically, small aluminum boats are known for being quite unstable on water. For example, small
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aluminum boat users are often forced to stay close to the centerline of their boats due to the fact that
movement to the outer edge of the boat causes larges angles of list, or tipping into the water. In fact, these
boats can become so unstable on water that movement of large masses, such as humans, to the outer edges
of the boat can cause the boat to capsize, therefore, one area requiring extensive research and calculations
was stability.
Research showed that a slight V-bottom boat was not only the best option from an off-road ground clearance
and ease of launch standpoint but also because of its increased stability on water. There are several factors
that play a significant role in determining the stability of a V-bottom aluminum boat. The most significant
factors include the location of the center of gravity of the boat, as well the width of the bottom of the boat.
After performing detailed research on other off-road campers currently on the market, it was determined
that the typical width of off-road campers are approximately 5 feet. Therefore, it was assumed that the
bottom of the boat hull portion of the camper should have a width that was close to the standard 5 foot
width. In order to determine the relationship between boat stability and width, engineering relationships
used in naval architecture were required. Detailed research of these relationships revealed that the models
which are used are very complex. Therefore, since complex models for stability calculations were difficult
to implement, by extensively simplifying the model, basic stability information could be derived.
Specifically, what was of interest was the angle and distance that the boat lists once a person on the boat
shifts to the outer edge of the boat. In order to further simplify the calculation, the boat was modeled as a
transverse 2D plane of the cross-section of the boat.
Several parameters were required to first be determined in order to calculate overall stability calculations.
The first parameter was the center of gravity. In order to determine the center of gravity of the boat, the
weights of major boat components needed to be taken into account as well as the weight of a person. The
weights that were assumed for each of the major components, as well as for the person, are shown in Table
6. Note that the center of gravity of the boat was the key component affecting the stability of a boat. In
essence, the lower the center of gravity of the boat, the more stable the boat was when floating and when
loads were shifted within the boat. The second parameter was the center of buoyancy of the boat that was
found using relationships developed in “Ship Stability for Masters and Mates.” Using naval architecture
theory along with these two parameters and basic trigonometry, the angle of list and distance that the boat
tips with shifting masses could be calculated.
Table 6: Component weights.
COMPONENT
WEIGHT [LBS.]
BOAT SIDES
90
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BOAT BOTTOM
250
MOTOR
60
FRONT, WINDSHIELD, HATCH
140
FLOOR
100
HUMAN
200
Assuming no external forces, such as waves or wind, and that the person was located at the centerline of
the boat, the boat sits transversally flat in the water with no list. In this scenario, the centers of gravity and
buoyancy of the boat are vertically aligned. However, when the person shifts to the outside of the boat, the
boat lists or tips in that direction. The boat lists in the direction that the person moves due to the fact that
the movement of the person causes the center of gravity of the boat to be shifted in that direction. The boat
has a listing moment until the center of buoyancy changes and aligns with the new, shifted center of gravity.
Under this methodology, Figures 3 and 4 were derived showing both the angle of list as a function of boat
bottom width and the distance that the side of the boat sinks into the water as a function of boat bottom
width.
20
18
Angle of List [deg]
16
14
12
10
8
6
4
2
0
30
35
40
45
50
55
60
65
Bottom Width [in]
Figure 3: Angle of list as a function of the bottom width of the boat.
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70
75
23
7
6
Tip Distance [in]
5
4
3
2
1
0
30
35
40
45
50
55
60
65
70
75
Bottom Width [in]
Figure 4: Distance boat lists into the water as a function of width of the boat.
From Figures 3 and 4, it was determined that a boat bottom width between 4 and 5 feet should not be an
issue from a stability standpoint. Ideally, the boat would be designed with a bottom width closer to 5 feet
because of the added stability. With the boat designed as such, if a person moved from the centerline of the
boat to the outer edge of the boat, an angle of approximately 6 degrees would be incurred, resulting in a 3
inch downward shift into the water. It was deemed by the team that this was an acceptable displacement.
Finally, it was worthwhile noting that the calculations performed are a simplified theoretical approximation
of the actual situation. In the realm of modern naval architecture, advanced and sophisticated computer
modeling is used to model and evaluate the stability of boats in all planes and axes of motion under an
extremely large number of conditions. While the model used to derive Figures 3 and 4 is very basic, after
correlating these calculations with information provided by boat owners with similar size boats, the
calculations appear to provide an acceptable approximation of the actual situation.
Since one of the major constraints for the Expedition Camper was that it must be lightweight, an analysis
was done to determine the overall weight of both the camper and the trailer. The first part of Table 7 shows
the approximate weight of major components on the camper and boat portion of the Expedition Camper.
Note that this was a dry weight, meaning, it does not include accessories such as furnishings and other
equipment and supplies. The second part of Table 7 shows the approximate weight of the trailer portion of
the Expedition Camper. The importance of this analysis laid in the fact that it showed that the project was
feasible from a weight standpoint. As an estimate, the team saw that the weight of the camper portion of
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the Expedition Camper was less than the max design constraint of 1,500 pounds. Furthermore, the total
weight of the camper was less than the max tow capacity of 2,000 pounds, from Table 4, of the typical
vehicle that would tow the Expedition Camper.
Table 7: Weight calculations.
Assembly
Component
Material
Weight [lbs.]
Hull
Aluminum
400
Base
Aluminum
150
Top
Steel/plastic/cloth
50
Steel/cloth
100
Floor
Wood
100
Hatch
Steel/glass
60
Wall/windshield
Steel/glass
80
Outboard motor
N/A
60
Battery
N/A
30
Fuel Tank
N/A
30
Boat/Camper
Roll bar
1,060
Sum
Trailer
Trailer frame
Steel
400
Leaf springs
Steel
60
Shocks
Steel
10
Jacks
Steel
30
Steps
Steel
15
Hitch
Steel
10
Wheels/tires
N/A
125
Sum
650
Sum
1,710
Total
5.1.2 Launch Parameters
An important aspect that was considered in the design of the Expedition Camper were factors affecting how
it was launched into the water. Typically, a boat launch or ramp is used to put a boat into the water. The
purpose of the boat launch is that it quickly increases the depth of the water with respect to distance from
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the edge of the body of water. In other words, a boat launch allows a boat to be easily removed from its
trailer. However, the Expedition Camper was capable of functioning on bodies of water which were out in
the wilderness where no boat launches were present. The Expedition Camper, therefore, was designed to
launch without a boat launch.
Basic buoyancy calculations revealed that that the V-bottom of the camper would rest at 6 inches below the
water line when it was floating. Figure 5 shows the relationship between the distances that the camper
sinks into the water and the weight of the camper. Note that this calculation assumes a bottom area of the
camper of approximately five feet wide by 10 feet long.
The Expedition Camper sat relatively high off of the ground for traversing rough terrain, but it was also
required that the camper needed to be low to the ground for ease of launching it into the water. The solution
to this conflict was to build an air bag suspension system for the trailer. Not only does this type of
suspension provide the necessary adjustments, it also provides a smoother ride for traversing rough terrain.
Note that the suspension will be discussed more in a later section of the paper.
Camper Weight [lbs]
2500
2000
1500
1000
500
0
0
1
2
3
4
5
6
Depth [in]
Figure 5: Distance Camper will sink into water based on weight.
Initially, the launch parameters were calculated based on the idea that the hull of the camper would be a
flat bottom and that the suspension of the trailer would be leaf springs. Due to the large off-road tires being
used, the Expedition Camper sits high on the trailer, approximately two feet above ground. Assuming a
scenario where the trailer enters the water with the bottom of the lake being flat, the Expedition Camper
required a minimum water depth of 30 inches for a successful launch. The water level after launch is the
water line that the camper floats at when in the water.
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Figure 6: Camper height dimensions for launch parameter reference.
As previously mentioned, the worst case scenario was a flat lake bed, requiring a 30 inch depth of water at
the tires to launch. This scenario was very unlikely, as most lake bottoms have a grade to some extent. The
distance from the hitch of the trailer to the wheel axle was 11.5 feet, and the distance from the wheel axle
to the back of the camper was 4 feet. Based on these dimensions, a one degree incline of the lake bottom
results in the back of the camper being approximately 3.25 inches below the hitch height. Furthermore,
each additional degree of incline dropped the back of the boat an additional 3.25 inches. In regard to the
degree of incline, the back of the camper dropped 0.84 inches below the axle height per degree of incline.
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B
A
Y
X
138”
θ
48”
For θ=1 degree:
Y = 138” x sin (1) = 2.41”
X = (138” + 48”) x sin (1) = 3.25”
X – Y = 0.84” therefore for every degree incline, the change in height between locations A and B is 0.84”
Figure 7: Dimensions and calculations to find height difference between points A and B.
For example, if the lake bottom had a ten degree incline, the back of the camper would be 8.4 inches below
the part of the camper in line with the axle. Due to this, any incline greatly increases the ease of launching
the camper. The back of the camper sat lower compared to the rest, and therefore entered the water first and
reduced the upward force that the camper experienced from the cross-beams of the trailer.
A typical scenario assessed involves a 5 degree grade for the lake bottom and a 12 inch bank on the sides
of the lake. Based on these values, the water depth required to launch the camper is 22 inches at the location
of the axle.
5.1.3 Boat Frame
5.1.3.1 Tub Section
The tub design of the camper was one of the most crucial components. Not only does the tub portion form
what would be thought of as the camper portion, the place where the living space is found, it also was the
general aesthetic makeup of the unit making it look more like a camper than a boat. The tub had a width of
59 inches and a length of 100 inches. Note also that these tub dimensions were the same as those found on
a Jeep Wrangler (years 1997 through 2006), thereby fulfilling the criteria that the camper was aesthetically
pleasing. Furthermore, a camper tub shaped and dimensioned after the Jeep Wrangler gives opportunity for
other Jeep-based accessories to be applied to the camper, such as the soft-top. Figure 8 below shows the
overall styling as well as approximate dimensions for the tub portion of the camper.
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Figure 8: Approximate dimensions for Jeep-styled tub portion of camper.8
5.1.3.2 Hull
Initially, the team intended to purchase an aluminum boat and then modify it to fit their desired
specifications, such as increasing strength in addition to changing the aesthetics to make it look more like
a camper. The plan was to install a Jeep tub into the aluminum boat, but it was determined that this option
would not be the best way to achieve the objective of making the camper aesthetically pleasing.
http://s213.photobucket.com/user/jscherb/media/Camper/DinootWide1_zpsf2cd9bcf.jpg.html?sort=3&o
=145
8
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Figure 9: Approximate boat hull dimensions.9
After an extended search for a used boat yielded no acceptable results, the team decided it would be best to
design and manufacture the entire boat from aluminum sheets. The primary reason why a suitable used
boat was not found was due to the fact that most aluminum boats containing the width and aesthetics that
the team desired, did not fit the team’s objectives well. While some boats were found that would have been
wide enough to fit the team’s specifications, these boats were also significantly longer than 16 feet in length,
which would have been undesirable in off-road situations, and in addition were quite expensive. As a result,
team decided that they could develop a better end product from both an engineering and cost standpoint by
starting fresh.
9
http://chicago.craigslist.org/nwi/boa/4225400901.html
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Figure 10: Frame of the camper.
The team chose to design the entirety of the camper using SolidWorks in order to ensure that the team’s
form and function objectives for the camper could be met, prior to building the prototype. SolidWorks was
used, as opposed to other 3D CAD packages, because of the familiarity of the team with it, as well as the
availability of the professional version of the software package at one of the team members’ place of work,
allowing the team to develop detailed prints of their design. The hull of the boat was designed as a 7 degree
incline.
5.1.4 Front Wall Section
The team decided that adding a front wall in the Expedition Camper would provide a way for it to be better
used as a camper. The front wall was designed to have a door in the center with two walls on each side. The
walls and the door each had a Plexiglas window in them. The top section of the wall was a modified jeep
windshield, and the bottom section was manufactured from sheets of aluminum. The door was also made
out of aluminum.
Several different ideas were considered for how the door would open. The intention for the door was to
have it be easy to open, out of the way, and aesthetically pleasing. The initial design had the door hinging
on its side. This feature allowed for it to stay open and the user to walk between the front and back portion
of the camper without having to duck through the doorway. This idea was later rejected and it was decided
that a door hinging upward would be the best option for several different reasons. First, the door has a bend
in it, so it would have to hinge to the side on either the bottom portion or the top portion. It was determined
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that this would not be aesthetically pleasing which lead to the final design of hinging the door on the top
and swinging upwards. Furthermore, the soft top needed to be latched to the front wall, so it was decided
to leave the entire top portion of the windshield, instead of cutting it in the middle. As a result, the user
would have to duck under the top part of the windshield to pass through the doorway, so having the door
swing to the side and out of the way was no longer useful. With this in mind, having the door hinge upward
was preferred over having it hinge to the side.
Figure 11: Front wall in camper frame.
The door was designed so that the user can get into the tub portion of the camper when the soft-top is up.
This way, when the Expedition Camper was being used for sleep and other camper purposes, the user may
move freely in and out of the camper through the use of the door. The door was approximately 2 feet wide,
and each side wall was approximately 1.5 feet wide. Rubber gaskets were placed on flanges that stand 1
inch out around the entirety of the doorway so that a proper seal could be made between the door and the
rest of the front wall.
5.1.5 Soft Top and Mount
Another key component in the design of the Expedition Camper was the top. The top of the camper must
be easily removed to allow for standing of occupants when the camper was used in its boat configuration.
However, not only did the top need to be easily removable, it also needed to be lightweight in order to
satisfy the weight constraints of the design. Under these criteria, it was determined that a top made of
waterproof cloth would be the best option, both from a lightweight and a simplicity point of view. Since
the team desires to incorporate Jeep-styling into the design, a Jeep soft top was the logical solution because
it satisfies all design constraints. While some modifications to the top were required to fit the exact
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application, the Jeep soft top was the perfect candidate. A 2004-2006 Jeep Wrangler LJ soft-top fit with the
current design dimensions and would only require modification of the side windows. Furthermore, the soft
top involved a framework that allows it to be easily removed by folding down. On a Jeep Wrangler, this
framework is connected to the roll bar. Initially, connecting the soft top to a roll bar inside of the camper
appeared to be the logical option for installing the soft top. Figures 12 and 13 show approximate soft-top
dimensions.
Figure 12: Approximate top dimensions.10
10
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Figure 13: Approximate roll bar dimensions.11
Throughout the design process it became clear that a roll bar would be less beneficial than had originally
been thought, because occupants would not be in the camper while it was being pulled therefore losing the
safety merit. Additionally the roll bar would be an additional obstacle when the camper was being used as
a boat and the top is down. Since the height of the roll bar from the camper floor was rather small, it would
be in the way of the user when they stand in the boat, therefore, a new design for the mounting system was
made. Traversing tubes were installed where the roll bar would be located allowing the user to hide the
supports in the wall while the top is down. From both a functionality and aesthetics point of view this was
a quality improvement.
5.1.6 Motor and Motor Mount
The motor mount was designed by the team and the motor was selected based on several boat dimensions.
5.1.6.1 Motor
Determining the power needed for the motor required some preliminary standards. The power required
depended on the intentions of the camper; namely if it was desired to be used to travel quickly across bodies
of water or to be more focused on casually trolling across the water. Due to the fact that the camper was
designed to be used for leisurely activities like fishing, it was assumed that the camper would not be required
to travel quickly across water. Research led to the basic rule for boating that 5 pounds of thrust is needed
11
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for every 200 pounds of boat weight. The team determined that the boat would weigh no more than 1500
pounds. Calculating the force required with that weight meant that the camper will need 37.5 pounds of
thrust. The main factor that went into choosing the motor was the length of the back wall of the camper.
This length of 27 inches was from the top lip down to the middle of the V-bottom. This length was quite
high compared to typical 12 foot aluminum boats, so instead of using a short shaft or long shaft motor, an
extra-long shaft motor was required in order to correctly align the propeller below the boat bottom. Based
on these specifications, a Johnson 9.9 hp extra-long shaft was being considered for the motor to be used for
the camper. The team considered building a storage space on the front of the trailer for the motor to be
stored in when towing the camper. Due to the limited budget, the team did not implement this into the
prototype but would suggest it as a possible improvement to pursue.
5.1.6.2 Motor Mount
Early on in the project it was decided to build a motor mount on the back of the camper that the motor could
be mounted to. A few benefits of having a mount were that the motor is not in the way of the soft top when
it was latched to the back wall of the camper, the motor could be more easily taken off and on when
necessary, and there was more space inside of the camper with the motor and gas can on the mount. In
designing the mount, the team had to make sure that the motor would correctly align with the bottom of the
boat depending on where the mount brackets were placed on the back panel of the camper. The team decided
to have the center of these brackets be two inches below the top of the wall in order to have close to 25
inches between the top of the mount and the bottom of the boat. Aesthetics also played a big role in the
design of the motor mount. The team wanted the mount to be modern looking and fit in with the rest of the
camper look. The width of the mount was chosen to be 45 inches and the height to be 12 inches. The mount
was made out of 1.5 inch OD steel tube with 4 crossbars and a 1/8 inch steel plate in the middle for the
motor to be mounted on. The plate of the mount was approximately 7 inches off of the back of the camper.
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Figure 14: Motor mount on back of camper frame
5.2
Trailer
The second major component from a design standpoint was the trailer. The trailer frame required design
and analysis in order to properly fit the camper features, such as the V-bottom. Other major design
characteristics possessed by the trailer include fenders, airbag suspension, tie down points, and a winch.
5.2.1 Trailer Frame
In the initial stages of the project the team wanted to buy a boat trailer and modify it to fit the overall shape
of the boat hull. After finding what was believed to be the best option for the purchase of a trailer the team
soon decided that it made more sense to fabricate a trailer from scratch. Using SolidWorks to design the
trailer the team was able to model a trailer with the desired profile and strength. An FEA model was also
created to make sure the design met the strength requirements. This model is discussed in the FEA section
of the report. One of the main issues that came up in the modification of a prefabricated trailer was the way
the team wanted the V-bottom shaped hull to sit on the trailer. Most boat trailers use bunks that sit up high
for the boat to rest on. Our design uses V-shaped cross members made from 3 inch x 2 inch steel tubing
with 1/8 inch thickness with UHMW strips on top to hold the boat. This way the camper can sit down in
the trailer, hiding its boat features and making it look more like a camper.
Several other modifications would have been needed to install the airbag suspension system the Expedition
Camper uses. By making the trailer from scratch, suspension brackets and airbag mounts could easily be
installed without many issues. The trailer frame itself was made from 4 inch x 2 inch steel tubing with 1/8
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inch wall thickness. The airbag mounts were made from ¼ inch thick steel plates to ensure that the integrity
of the trailer will not be compromised.
5.2.2 Hitch
Since the goal of designing the camper was to make it as rugged as possible, the trailer hitch needed to
match this goal as well. It was determined that a regular, conventional trailer hitch will not suffice for this
project because of its lack of mobility. A regular trailer hitch has only one degree of freedom that allows it
to rotate around the ball it is connected to. In order for the hitch to be able to fully function as needed in an
off-road situation, it was determined that the hitch needed to have three degrees of freedom. Two options
evolved from this issue; build one or buy one. After doing some research, an appropriate hitch was found
that could be purchased. Lock N’ Roll12 designs and manufactures many types of off-road hitches for
trailers. Figure 15 shows an example of one of their particular hitches.
Figure 15: 501 with a 510 off-road trailer hitch by Lock N’ Roll13
Unfortunately, the price of this hitch was just over $200 which was too large of an expense given the
project’s budget. Further research showed that $150-$300 was a fairly common price range for these style
hitches, and building one was much cheaper than buying one. Due to the large differences in prices, the
12
13
www.locknroll.com
https://locknroll.com/gallery/gallery-category/
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37
team decided to manufacture a hitch to decrease expenses. A search of multiple trailer forums proved
effective in finding a design for the necessary hitch. Using SolidWorks, a model for the hitch was then
created, and is shown in Figure 16.
Figure 16: Solid works model of three axis hitch.
This hitch was designed by Jeff Scherb and has been used with his consent. This hitch has the ability to
rotate around the three axes of a standard three-dimensional coordinate system.
The hitch was a critical aspect to allow the camper to go off-road, therefore the team determined that an
analysis of the hitch was warranted. Rather than perform an extensive finite element analysis of the entire
hitch assembly, the analysis was simplified down to determining the strength of the pins and bolts in the
hitch. Since the diameters of the pins are smaller to the diameters of the bolts and are made from the same
material, the pins would be the first part to fail.
Since the pins would be in shear and not in tension, the shearing force needed to break the pin was calculated
using the tensile strength of steel and the cross sectional area of the pin. As previously stated, the tensile
strength of steel is approximately 58,000 psi. Assuming that the shear strength of a material is roughly
equal to one half of the tensile strength of a material, the shear strength of steel is approximately 29,000
psi. Using this value and a 5/8 inch diameter pin, the shearing force required to fracture the pin was
calculated to be 8,900 pounds. This force is much higher than the anticipated total weight of the combined
trailer and camper, which is approximately 1000 pounds, thus making the hitch safe to use.
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5.2.3 Suspension
One of the key areas of the trailer on which the team focused was the suspension design. Typical boat
trailers have a leaf spring suspension system that absorbs various loadings and vibrations, resulting in a
smoother, less stress-intensive ride. For the application of this camper, the team looked at two different
suspension styles; leaf springs and air bags.
5.2.3.1 Leaf Springs
Most boat trailers use leaf springs for the suspension system because leaf springs are inexpensive, readily
available, and easily mountable to a trailer frame. However, they do not allow for any vertical adjustment
of the trailer, which could be an issue when trying to launch the Expedition Camper in a location where
there is not a standard boat launch. Figure 17 provides an example of a typical leaf spring suspension system
on a trailer.
Figure 17: Leaf spring suspension system.14
The leaf spring form of suspension was what the team intended to use on the trailer due to simplicity as
well as budget constraints. Later in the semester it was decided that air bags would be a better option, but
this was after leaf spring calculations were performed.
As stated earlier in the report, one of the objectives for the Expedition Camper was that it would have the
ability to survive a 1 foot drop. To meet this requirement, calculations were performed on leaf springs to
determine the level of stress that they would experience in various scenarios. The first calculation was used
to determine the maximum stress that one of the leaf springs would experience if subjected to a dead load
of 1000 pounds. This resulted in a maximum stress of 85.9 MPa. The second calculation was used to find
the maximum stress that would be experienced by one of the leaf springs if loaded with 1000 pounds and
subjected to a sudden drop of 1 foot. This resulted in a maximum stress of 482.5 MPa. Because the yield
14
http://www.personalwatercraft.com/products/what-to-look-for-in-a-pwc-trailer-1159.html
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39
strength of common 5160 grade leaf spring steel is 670 MPa, the trailer leaf spring has a safety factor of
1.39 in the event of a 1 foot drop. Figures 18 and 19 shown below, provide a summary of the impact forces
and stresses experienced by a leaf spring when subjected to different drop heights under the assumption of
a 1000 pound load on the spring.
30000
Impact Force [N]
25000
20000
15000
10000
5000
0
0
0.2
0.4
0.6
0.8
1
1.2
1
1.2
Drop Height [ft]
Figure 18: Force on leaf spring as a function of drop height.
600
Impact Stress [MPa]
500
400
300
200
100
0
0
0.2
0.4
0.6
0.8
Drop Height [ft]
Figure 19: Stress on leaf spring as a function of drop height.
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5.2.3.2 Air Bags
While the team had initially intended to use a leaf spring form of suspension for the trailer, this plan changed
when Air Lift Company, based out of Lansing, Michigan, graciously agreed to donate a set of suspension
air bags for the project. This was an exciting addition to the project from several aspects. Not only do the
air bags provide a smoother ride off-road than the leaf springs, they also allow for the height of the trailer
to be adjusted. Thus, the height of the trailer could be raised for traversing over large obstacles, and also
lowered to allow for ease of launching the camper in remote locations where no boat launches are present.
After researching several air bag suspension designs currently on the market, the team set out to design and
build one suited to their trailer. The team chose to build a trailing-arm style suspension, similar to the one
shown in Figure 20. The picture shows independent arms on each side of the trailer for additional flexibility
when driving over rugged terrain. However, the air bags can also be connected to a single axle without
being cut. While driving, the air bags are filled with compressed air to allow fluid movement. The air bags
can also be deflated, by releasing the air, to lower the whole trailer by several inches.
Figure 20: Air bag suspension system.15
The team began by designing the trailing arms that attach the axle to the frame. Based on research, material
availability, and desired strength characteristics, it was decided that the arms would be made out of 2 inch
by ¼ inch wall square tubing. Furthermore, in order for the suspension to be extremely robust, the geometry
of the arms was developed so as to minimize twist and deflection of the arms when traversing over rough
terrain. The entire trailing arm suspension set up was modeled in SolidWorks in order to aid in this design.
Using research in conjunction with the SolidWorks model of the trailer, it was determined that the arms
should be approximately 2 feet in length. Triangulation and bracing was an important feature in designing
15
http://www.naxja.org/forum/showthread.php?t=1002676
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these arms in order to make them extremely stiff so that they would not bend or deflect when subjected to
large forces. Figure 21 below shows a SolidWorks model of one of the arms. The bottom ends of the arms
were notched and welded to the axle tube, while the top ends of the arms, each designed with two bushings
spaced a large 16 inches apart, were bolted to a cross member that was welded to the trailer frame. Because
of their ready availability, ½ ton Chevrolet leaf spring bushings were used to connect the arms to the cross
member of the trailer, and thereby damp vibrations experienced by the trailer. The cross-member, attaching
the arms to the trailer, was constructed out of 2 inch by 3 inch by 1/8 inch wall steel tubing, and the arms
were attached to the cross member using laser-cut, ¼ inch steel plates. Finally, the air bag mounts and
shock tabs were made from laser-cut, ¼ inch steel plates.
Figure 21: Arm for air bag suspension.
Several calculations were performed with regard to the air bag suspension. In order to analyze the air bags,
they were modeled as thin-walled pressure vessels. The maximum stress experienced by the air bags when
the bags were at an internal pressure of 30 psi was a stress of 125 psi due to the axial load of the trailer and
camper as well as the internal pressure of the air bags. The air bags are rated for a pressure of 600 psi, which
is far from what they will experience when riding with an internal pressure of 30 psi.
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5.2.3.3 Air Suspension Control
From a control standpoint, it was determined that a pressure regulator connected to an air tank would control
the pressure of the air bags. This would allow the height of the trailer to be raised or lowered by the bags
that have an overall stroke of 9.7 inches.
5.2.3.4 Axle, Tires, and Shocks
Based on the width of the trailer frame, a standard 76-inch wide, 3500 pound capacity trailer axle was
selected and purchased from Holland Trailer in Holland, Michigan. It was further determined that large 35
inch tires would be used for the trailer because of the off-road capability that they added to the project. The
tires were pre-owned by the team and therefore did not need to be purchased. As specified by the
manufacturer, the air bags have a minimum height of 2.8 inches and a maximum height of 12.5 inches. At
ride height, the air bags are approximately 6 inches tall, which when combined with the 35 inch tires, causes
the trailer to have a height of 28 inches above the ground. On the other hand, when fully deflated, the trailer
has a height of 22 inches above the ground. Note that when fully deflated, the trailer frame rests on a set of
bump stops designed to contact the axle in order to protect the air bags. Finally, a set of shock absorbers
were added to the suspension design in order to dampen vibrations experienced by the suspension.
5.2.4 Tie Down Points
During the design process several methods for attaching the boat to the trailer were considered. These ideas
included; cutting slots in the trailer frame for tie down hooks to grab onto, welding slotted angle brackets
to the trailer, and welding eye bolts to the trailer. A consensus was reached to use the eye bolts because of
their simplicity and size. One inch inner diameter eye-bolts were welded at the back end of the trailer frame.
These bolts are strong enough to handle any forces on them that may result from the camper bouncing
around while being towed off-road. The camper will remain secured to the trailer through the use of the
two tie down points in the back and the winch in the front.
5.2.5 Straps
In order to ensure that the camper properly sits on the trailer, a set of ratchet straps was purchased. These
straps had to be strong enough to hold the camper in place while being pulled over rough terrain. This meant
that a lot of force will be acting on the straps, therefore proper size was considered. The team determined
that if the camper were to bounce excessively a strap would feel the entire weight of the camper, which was
determined to be approximately 1000 pounds. By using this information the team decided to purchase two
straps that are each rated for a working load limit of 1200 pounds, so that each exceeds the weight of the
boat. This provides a large safety margin and ensure that the boat will stay secured to the trailer.
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5.2.6 Trailer Jacks
When the Expedition Camper is being used on land for camping purposes, it will require support for when
a person is inside of it. Four jacks will be included with the camper to place at each corner in order to
stabilize it, similar to typical campers used today. Because off-road tires will be used for the camper trailer,
the camper will be sitting fairly high off the ground. The axle of the trailer will be 17 inches above the
ground, and the base of the trailer around 5 inches above the axle, making the required height for the jacks
to be a minimum of 22 inches extended.
Two different types of jacks were considered for the Expedition Camper: stacker jacks and scissors jacks.
Images of each are shown below in Figure 22.16,17
Figure 22: Stacker jacks and scissors jacks.
Stacker jacks are fairly cheap, but no sizes have been found to be adjustable to more than 17 inches. Scissor
jacks on the other hand are more expensive, but do have a larger variety of ranges, some of which being
able to extend to more than the 22 inches required. One consideration was having blocks to be placed under
the stacker jacks, giving them the extra 5 inches needed. This option was decided against because it would
not be as stable and would take up more storage space. After discussing the available options, it was decided
that the best option is to use 30 inch scissors jacks, costing around $100 for the pack. These were the best
option because, although they cost more, they provide a safer and more secure foundation for the camper,
adhering to the design norm of trust.
Due to budget constraints, the team decided not to go forward with purchasing the trailer jacks. The jacks
are a potential future addition to the Expedition Camper.
5.3
Finite Element Analysis
In order to determine if the design would be feasible, basic calculations and conceptual drawings were done.
The size of the trailer and boat determined the overall dimensions of several other pieces in the design. The
team set a baseline parameter for the trailer to be able to withstand a one-foot drop, simulating what may
16
17
http://www.etrailer.com/Trailer-Jack/Stromberg-Carlson/JSC-30.html
http://www.etrailer.com/Trailer-Jack/Ultra-Fab-Products/UF48-979003.html
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be encountered when running over a rock, and remain structurally intact. The team also performed stability
and buoyancy calculations to determine how the camper would perform on water. Under the assumption of
impact forces, FEA analysis was used to evaluate the structural integrity of the design.
Finite Element Analysis (FEA), using Algor Multiphysics Simulator, was deemed to be a crucial tool in
developing the design. Approximate models of the camper and trailer were developed to determine if the
designs would hold up under impact loads of 6,000 pounds. After determining that the trailer and camper
could, in fact, withstand these forces, more refined models were developed and simulated in the FEA
program based on the designs the team created.
5.3.1 Camper/Boat FEA
Initial FEA models of the camper were constructed based on the fact that the team would be using bunks
in order to set it on the trailer. Figures 23 and 24 show the maximum stress and displacement of the camper
under what was deemed worst case scenario. This scenario puts a force of 3,000 pounds on the camper and
the analysis shows that, with aluminum material, the design will hold and does not displace enough to
compromise other parts of the design.
Figure 23: Boat stress FEA.
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Figure 24: Boat deflection FEA.
From this the team decided to continue to refine the design of the camper itself, knowing that we could
build a unit that would meet the standards set for it. After continuously improving the design of the camper,
which included the addition of braces along the flooring, a final design was reached in which another FEA
model was created to double check the strength and durability of the camper. Figure 25 shows the stress
analysis for the final camper design. Unlike the first model, the camper does not rest on bunks, but instead
rests on ¼ inch UHMW strips mounted to steel 3 inch x 2 inch cross beams. The final model simulates the
worst case scenario of the weight dropping down all at once. Again this would be the 3,000 pounds used
earlier, only it would be dispersed over a different surface area than that of the original model. The design
changed somewhat so the model only showed and maximum stress of 400 psi. This is much lower than the
stress of 5052 aluminum and will be able to withstand the required impact loads.
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Figure 25: Final camper/boat FEA model.
5.3.2 Trailer FEA
In order to ensure that everything in the design is safe during travel, FEA analysis was done on the trailer.
The team made sure that the trailer could withstand the impact forces resulting from traveling over rugged
terrain. If the trailer were to fail, the whole unit would be suspect to breaking.
Using impact force equations, the team calculated that if the trailer were to be pulled over a one foot dropoff, the force experienced by the trailer would be equivalent to about 6,000 pounds of static load with a
safety factor of 2. The same method was used for the trailer design as was used for the boat. Rough models
were simulated up front to make sure a basic trailer design would meet the team’s goals. According to the
first FEA model, the maximum force experienced by the trailer was 68,000 psi. Note this assumed a worst
case scenario of one wheel absorbing all the impact. The ultimate tensile strength of ANSI 1080 annealed
steel is 89,250 psi. Therefore, according to this simulation, the design should not fail. The team also made
sure the displacement would not be excessive and compromise other parts of the unit. The maximum
displacement of the trailer itself does not exceed 1.12 inches according to the model. Both the strength and
displacement diagrams are shown below in Figures 26 and 27.
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Figure 26: Trailer stress FEA.
Figure 27: Trailer displacement FEA.
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After determining that a trailer design similar to the first crude models would work, further refinement went
into the trailer and more detailed drawings were made. Once the team reached a final design, another FEA
simulation was performed on the final design. Another additional simulation was also completed on the
suspension brackets because this is the main connection between the frame and axle of the trailer and would
be where the highest stresses would occur. Figures 28 and 29 below show the air bag bracket FEA and
trailer FEA respectively.
Figure 28: Airbag mounting bracket FEA simulation.
The simulation above applies a maximum load of 6,000 pounds on the bottom of the bracket. The model
shows that a maximum stress of around 27 ksi will be reached. This stress is well below the yield stress of
the steel, so the team is confident that the airbag mount will hold up under strenuous conditions.
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Figure 29: Stress FEA of final trailer design.
Again a 6,000 pounds was applied in the above model, but the force was applied downward to the cross
members of the frame. The tongue of the trailer and the locations in which the airbag mounts are located
were fixed to simulate a realistic loading. According to the model, the maximum stress on the trailer will
reach 24 ksi which is below the yield strength of steel, therefore, the design will meet the required criteria.
6 Testing
In order to ensure that the final product meets the standards set forth, multiple tests are going to be
performed on the finished product. One area of testing was the safety for the user in different functions of
the Expedition Camper. More specific tests were planned to be performed to confirm if the team’s
objectives were met. These tests included a drop test, a launch capability test, and a stability test.
6.1
Safety
Safety was the team’s biggest concern when it came to the actual operation of the product. In order to ensure
that the final product was safe for users, the team planned to perform basic tests that aimed at possible
safety risk areas. These included the procedures of launching the unit into the water, hooking up the hitch
to the vehicle, setting up and taking down the soft-top, moving in and out of the camper, and typical use of
operating the motor. During the test each member planned to document any concerns or ergonomic
problems that arose in the process. Along with this, the team planned to simulate a typical outdoor adventure
where each feature would be used.
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6.2
Initial Testing
Testing had not yet been performed as the camper was not completed until the day of the senior design open
house. If the team were to continue with testing, there would be three tests that the team would like to have
performed.
6.2.1 Drop Testing
The drop test would involve towing the trailer with the camper on it over a one foot drop-off. The test would
be performed multiple times, with inspection of the trailer and camper occurring after each trial. If there
was not any notable damage to the camper or trailer, the unit would have passed the test.
6.2.2 Launch Testing
Launch testing would involve launching the camper in several different areas. The purpose of this test was
to get an idea of how easy it is to launch the boat in various water depths and shoreline conditions. The
testing would be performed by one person. The person must have easily and safely been able to remove the
camper from the trailer into the water as well as load the camper back onto the trailer.
6.2.3 Stability Testing
Stability testing would involve getting the camper out on the water and testing its stability in two cases,
when traveling and when at rest. Testing would occur by moving to one side of the boat and approximating
the amount of list that resulted in this shift. The distance of tilt would be measured while the camper was
at rest by driving a stake into the ground next to the boat and then marking on the stake where the camper
edge lies before and after the person shifts to the side. The testing while traveling would require an
estimation for the distance of tilt as the camper would be moving too fast to get a measurement in this way.
6.3
Modifications
If any of the tests failed the camper and trailer would have been analyzed in order to figure out the reason
for failure. If possible, modifications would have been made so that the camper and trailer would not fail
in the given scenario.
7 Business Plan
7.1
Market Competition
There is nothing on today’s market that serves the same purpose as the Expedition Camper. However, there
are currently some campers designed to be hauled to places of which a typical camper or boat cannot go.
The unique aspect of the Expedition Camper is that it serves multiple purposes as a camper and a boat. For
the purpose of studying the marketability of the product, the team considered the Expedition Camper as
part of the market of durable off-road campers. The fact that it can be used as a boat was considered market
differentiation and an expansion to the market of durable off-road campers.
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51
The off-road campers currently on the market range greatly in complexity. The complexity greatly depends
upon how many accommodations are built into the camper. Three major off-road campers and their selling
prices are shown in Table 8.
Table 8: Off-road campers and their base purchase prices.
TRAILER
BASE PRICE [$]
MOBY 1 XTR18
16,500
SO-CAL TEARDROPS
14,995
THE KRAWLER19
ADVENTURE TRAILERS
TEARDROP
7.2
13,852
20
Break-even Analysis
To estimate the approximate cost of producing the Expedition Camper, research was done regarding the
fixed and variable annual costs that correspond to the various components of the camper. The costs of each
component are shown in Table 2 of Section 2.3. To determine a production cost estimate, all of the costs
that corresponded to each camper were recorded, as well as all of the annual fixed costs such as building
rent, machinery, and insurance. A table of these costs is shown below.
Table 9: Cost per camper and annual fixed costs.
PRODUCTION COST ESTIMATE
Description
COST PER CAMPER
ESTIMATED
$2,000
LABOR
RAW MATERIALS
$2,270
MARKETING
$1,200
DISTRIBUTION
$1,500
ANNUAL FIXED COSTS
UTILITIES
$40,000
WORK AREA RENT
$75,000
INSURANCE
$10,500
PATENT
$10,000
PROTOTYPE
$30,000
MACHINERY
$100,000
DESIGN
$100,000
Total Cost
40 hr @ 50$/hr
$6,970
Description
Total Cost
10,000 @ $7.5/ft2
10% of building/equip. cost
$365,500
18
http://moby1trailers.com/moby1-xtr/
http://www.socalteardrops.com/page.php?p=22
20
http://www.adventuretrailers.com/teardrop.html
19
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In order to choose a reasonable price to sell the Expedition Camper, break even analysis was performed to
find the minimum required sale price to break even. Below is a summary of the costs and sale price required
to break even based on a production rate of 30 units per year.
Table 10: Break Even Analysis for Expedition Camper.
BREAK EVEN ANALYSIS
ANNUAL PRODUCTION
ANNUAL FIXED COSTS
COST PER VEHICLE
TOTAL ANNUAL COST
BREAK EVEN SALE
PRICE
30
$365,500
$6,970
$574,600
$19,153
8 Conclusion
At the beginning of the year, the team developed the idea of a unit that can be taken off-road and used as
both a camper and a boat. Several objectives were established for the Expedition Camper to meet. Over the
final two semesters at Calvin the team designed and manufactured the Expedition Camper in pursuit of the
goal of dual functionality. The camper’s complex design and robust construction allow it to be pulled over
large obstacles encountered on off-road trails as well as be removed from the trailer and placed into a pond
or lake so that it can traverse across water. With clever design work, detailed engineering calculations, and
innovative construction, the team was able to build a unit that has proven to be capable of being towed offroad and used for various purposes as a camper and a boat.
If further work were to be performed on the project or if a second prototype were to be developed, it would
be worthwhile to make several changes and additions. One addition that would be beneficial to the project
would have been to design and install longitudinal bracing in the boat bottom to prevent the bottom from
becoming wavy when welded. A second addition that should have been implemented was a door handle.
The door handle should have a cam latch that could lock the door down. Gasket should also be added to the
flange of the front wall so that a proper seal is made between the door and the wall. An air tank or
compressor would also be mounted on the front of the trailer so that the air bag suspension may be cycled
when out in the wilderness. One final addition would be that the inside should be furnished with various
accessories needed for camping and boating purposes.
One thing that the team would have done differently in the design was to lower the winch mount. It rested
close to level with the tie down of the boat, but should have been lower than the tie down so that it could
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pull the boat downward when securing it to the trailer. Another change that the team would have made was
to either shorten the back of the camper or implement a steering and throttle system so that the camper may
be driven with the top up.
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9 Acknowledgements
The team would like to acknowledge the following people for their support and help on the project.
Ned Nielsen – Engineering Professor and team advisor
Terry VanHaitsma – Premier Metal Products, fabrication and welding
Phil Jasperse – Metal shop instructor and manufacturing mentor
Josh Noling – Progressive Surface
Jordan Hiemstra – Industrial Designer
Dave Hiemstra – Painting
Nel Osterwald – Custom canvas work
Jeff Scherb – Aftermarket Jeep parts designer
Dave Kramer – Cascade 4WD
Nate Holstege – Preferred Machine, laser cutting
Megan Smith – Schupan, aluminum supply
Jeremy Hart – Airlift, airbag donation
Nick Capinski – Eastwood Company, primer donation
Wyrick’s – Paint supplier
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10 Bibliography
Cabela's World's Foremost Outfitter. N.p., n.d. Web. 28 Nov. 2013.
<http://www.cabelas.com/product/Trolling-Motor-Buyers-Guide/532011.uts>.
Derrett, D. R., and Bryan Barrass. Ship Stability for Masters and Mates. Oxford: Butterworth-Heinemann,
2006. Print.
Engineering Toolbox. N.p., n.d. Web. 7 Nov. 2013. <http://www.engineeringtoolbox.com/>.
Riley, William, Leroy Sturges, and Don Morris. Mechanics of Materials. 6th ed. N.p.: Wiley, n.d. Print.
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Appendix A: EES Calculations
"Volume of box"
L_box=8 [ft] * convert(ft, m)
{H_box=(4/12) [ft] * convert(ft, m)}
H=H_box*convert(m, in)
W_box=5 [ft] * convert(ft, m)
Vol_box=L_box*H_box*W_box
"Volume sides"
W_bottom= 52 [in] * convert(in, m)
Vol_sides=(0.5*L_side*H_side*L_box)*2
L_side=(W_box-W_bottom)/2
H_side=H_box
"Volume of curve"
W_curve=W_box
A_curve=2 [ft] * convert(ft, m)
B_curve=H_box
Vol_curve=pi*A_curve*B_curve*W_curve
"Total volume"
Vol_tot=Vol_box+Vol_curve-Vol_sides
Vol_tot_ft=Vol_tot*convert(m^3, ft^3)
"Density of water"
T=298 [K]
P=101.325 [kPa]
rho_water=density(steam, T=T, P=P)
"Weight of fluid displaced"
m_dis=Vol_tot*rho_water
F_dis=m_dis*g
g=9.81 [m/s^2]
F_water=F_dis*convert(N, lbf)
{F_water=1500 [lbf]}
"Trolling Motor"
lb_Thrust_needed = (F_water/200)*5
every 200 lbs weight"
"General Rule of thumb being 5 lbs thrust for
"Shaft Selection"
"Assume 22inch high boat"
H_boat = 22 [in]
Waterline_height = H_boat - H
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57
"!Stability - angle of list"
"Boat Weights"
W_side=90 [lbf]
W_bottom=250 [lbf]
W_motor=60 [lbf]
W_front=140 [lbf]
W_man=200 [lbf]
W_floor=100 [lbf]
"Heights of mass centers"
y_side=11 [in]
y_bottom=0 [in]
y_motor=22 [in]
y_front=23 [in]
y_man=44.32 [in]
y_floor=4 [in]
"Horizontal distances of mass centers"
x_width=60 [in]
x_side_1=0 [in]
x_side_2=x_width
x_bottom=x_width/2
x_motor=x_width/2
x_front=x_width/2
x_man=x_width/2
x_floor=x_width/2
"Center of gravity"
Sum_weight=W_side*2+W_bottom+W_motor+W_front+W_man+W_floor
x_bar=(W_side*x_side_1+W_side*x_side_2+W_bottom*x_bottom+W_motor*x_motor+W_front*x_front+W
_man*x_man+W_floor*x_floor)/Sum_weight
y_bar=(W_side*y_side*2+W_bottom*y_bottom+W_motor*y_motor+W_front*y_front+W_man*y_man+W_fl
oor*y_floor)/Sum_weight
"Stability parameters"
BM=(L*(B^3))/(12*V)
V=L*B*Draft
L=96 [in]
B=x_width
Draft=4 [in]
KB=(1/2)*Draft
GM=BM-BG
BG=KG-KB
y_bar=KG
"Angle of list"
GG_1=(W_man*d_shift)/Sum_weight
d_shift=x_width/2
tan(theta)=GG_1/GM
"Distance tip"
Tip=tan(theta)*x_width/2
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58
Appendix B: Design Drawings
Preliminary Design Drawing
Figure 30: Preliminary design drawing.
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59
Current Design Drawings
Using the design process shown above, the following design drawings were developed.
Figure 31: Side view, top down.
Figure 32: Side view, top up
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60
Figure 33: Front View
Figure 34: Top View
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61
Figure 35: Boat removed from trailer.
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62
Figure 36: Colored side view, top down.
Figure 37: Colored side view, top up.
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63
Figure 38: Colored perspective view showing entrance.
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64
Appendix C: Budget
Table 11: Complete Project Budget
Component
Boat
5052 Aluminum 0.160" thick, 2
sheets 48" by 96", 2 sheets 60" by
144"
Boat Forming and Welding
Cutting of Aluminum
Tie down points for trailer, 2 rear
and 1 front
Bending of soft top mounting rails
Windows, 1/4" plexiglass
Window gasket material
1997-2006 Jeep TJ/LJ Windshield,
top gasket, hinges, and bolts
Indoor/outdoor carpet
Boat Plug
Light Khaki Metallic Paint, 2 quarts
Door piano hinge, 21" long
Door latch
Door gasket
Wood flooring - 3/4" plywood, 4'x8',
3 sheets, exterior BC grade
Misc Hardware - screws for floor,
shock mount bolts, motor mount
bolts, etc.
Door aluminum, 0.125" thick, 36" by
48", 3003 grade
Door cutting
Windshield steel
Aluminum angle for floor support,
2"x2" by 0.125" thick, 24 ft
Epoxy primer
Motor Mount
Motor
Tubing - 1.5", 1/8" wall, 15 ft
Bushings - 4 shackle bushings for
Jeep CJ7
DOM for bushings, 1.5", 1/4" wall, 8"
Aluminum attachment brackets
Steel plate for mount, 0.125" thick
Board for motor mount
Top
Canvas material, LJ soft top
Source
Cost
Schupan
Premier Metal
Preferred Machine
Calvin Metal Shop
Quality Sheet Metal
Menards
Mcmaster
Pete's Auto
Parts/Craigslist
Menards
Gemmens
Wyrick Company
Machine shop
Ebay
Hiemstra
Menards
$653.92
$1,900.00
$183.00
$0.00
$5.00
$60.00
$28.00
$150.00
$25.82
$4.23
$55.00
$0.00
$20.00
$0.00
$101.00
Menards
$36.81
Calvin Metal Shop
Preferred Machine
Quality Sheet Metal
Calvin Metal Shop
$0.00
$22.00
$52.00
Eastwood
$0.00
$0.00
Mast
Calvin Metal Shop
$0.00
$0.00
Hiemstra
Calvin Metal Shop
Calvin Metal Shop
Calvin Metal Shop
Menards
Craigslist
This document is the property of Team 14: Expedition Camper (Calvin College).
Duplication of any portion of this document may only be done with team consent.
$0.00
$0.00
$0.00
$0.00
$0.00
$50.00
65
Jeep LJ soft top canvas, windows,
and hardware
Aquaview 40 ga, dark smoke tint
vinyl
Soft top mounts - 2"x2"x1/8", 8ft
aluminum tubing
Soft top mount - 1.75"x1.75"x1/8",
35.4 inches aluminum tubing
Soft top alteration
Canvas parts - buttons, velcro,
zippers, thread, etc.
Aluminum strips for zippers on
windshield
Trailer
Raw Materials, 4"x2" and 3"x2",
0.125" wall
Axle
Tie down points - eye bolts
Paint - black
Airbag Suspension
Mounting Bars/Brackets for arms
U-Bolts
Ratchet Straps
Cable Ties
Grip Tape
Misc Nuts/Bolts
Monroe shocks
Shock mounts
Bump stops
Arm bushings
Arm bolts
Wheel adapters
35" tires and aluminum wheels
Shock mount laser cuts for axle
UHMW strips
Trailer fenders
Airbag mounts
Push-In Grommets
Fender lock washers
Fender wide washers
Fender bolts
Winch
Air fittings
Air line
Regulator
2"x2", 0.25" wall steel tubing for
arms, 13ft
Craigslist
Canvas Innovations
Calvin Metal Shop
Schupan
Nel Osterwald
Nel Osterwald
Calvin Metal Shop
Progressive Surface
Holland Trailer
Progressive Surface
Tractor Supply
Airlift Company
Premier Metal
AB Spring Service
Gemmens
Gemmens
Gemmens
Gemmens
Cascade 4wd
Cascade 4wd
Cascade 4wd
Cascade 4wd
Cascade 4wd
Craigslist
Hiemstra
Premier Metal
Progressive Surface
Premier Metal
Premier Metal
McMaster
McMaster
McMaster
McMaster
Harbor Freight
Calvin Metal
Shop/Innotec
Innotec
Calvin Metal Shop
Premier Metal
This document is the property of Team 14: Expedition Camper (Calvin College).
Duplication of any portion of this document may only be done with team consent.
$230.00
$144.11
$0.00
$25.72
$0.00
$64.87
$0.00
$175.00
$102.00
$0.00
$50.00
$0.00
$0.00
$11.83
$18.01
$2.53
$13.77
$0.69
$20.00
$5.00
$17.00
$40.00
$6.00
$30.00
$0.00
$0.00
$0.00
$0.00
$0.00
$8.08
$5.21
$6.66
$9.73
$30.73
$0.00
$0.00
$0.00
$0.00
66
DOM tubing for arm bushings, 2",
0.25" wall
Epoxy primer
Winch mount plates, 2
3"x2", 0.125" wall steel tubing, 22"
long
2"x2", 0.125" wall steel tubing, 12"
long
Premier Metal
Eastwood
Calvin Metal Shop
Progressive Surface
Calvin Metal Shop
Hitch
Premade hitch
2" OD, 1.5" ID square tubing
2.5" x .25" wall Steel Tubing
1"-8 x 6" grade 8 bolt
Top Link Ball, Category 2
Sleeve 1"ID, 1.25" OD
Category 3 to 2 Top Link Bushing
.75" ID/1" OD Bushing
.75" OD, 5/8" ID Bushing
1" grade 8 bolt/nut/washers
1" ID, 1.25"OD Sleeve
1.25" shaft collar, 2" OD
Hiemstra
Calvin Metal Shop
Calvin Metal Shop
McMaster
Tractor Supply Company
Tractor Supply Company
Tractor Supply Company
Tractor Supply Company
Tractor Supply Company
Calvin Metal Shop
Tractor Supply Company
Tractor Supply Company
Other
Sand for blasting
Menards
Total
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$0.00
$9.76
$8.99
$2.99
$8.97
$2.29
$1.99
$0.00
$2.99
$4.99
$24.00
$4,430.69
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