Engr 5011 Resistance & Propulsion of Ships
Resistance Laboratory: Winter, 2008
Purpose
• The purpose of the resistance laboratory is to become acquainted with the process of planning and
executing and model test program, and analyzing the test data in order to make full-scale
predictions of ship resistance for the smooth hull. Keep a detailed log (1 per team) of the
experiment.
• The test data are to be analyzed in accordance with the ITTC 57 & 78 methods. Form factor is to
be determined using Prohaska’s method. Blockage correction is to be made using Conn’s method, if
necessary.
Model Preparation and Setup
• The model is to be ballasted to its target displacement and draft. Use the waterline marks as
guidelines for setting the trim condition. When ballasting, make sure that you make allowances for
any equipment that is to be added to the model (e.g. instrumentation, tow post, etc.). Check these
weights and their locations with the Technician and/or TA. Ballasting can be done in the small trim
tank prior to testing, but must be carefully checked when the model is in the tow tank.
• Install the model in the tank and calibrate the resistance dynamometer with Jim. Note the
installation and calibration procedures. Note the presence of any appendages on the model.
Test Plan
• Prepare a test plan that incorporates the requirements of the analysis. For example, as the form
factor is to be determined from the experiments, it will be necessary to do about 10 tests at Froude
numbers in the range 0.1≤Fn≤0.22. It could be instructive to do a couple of extra runs at even lower
Froude number (say 0.05 and 0.08). In addition, any speeds required above a Fn of 0.22 should be
done at an interval of not greater than 1 knot full scale. Plan your test program so that you get at
least 12 points. If you want to do more tests, you can decrease the speed interval.
• Note that it is good practice to randomize the test program to avoid running all tests in either
ascending or descending order.
• Measure the water temperature at the beginning and end of the program.
• Note that it is required that you check the resistance data at the end of every run (during the tank
settling time). The check includes checking the time history for any anomalies and plotting the
results. For example, the simplest check would be to plot measured resistance (tared) versus model
speed. If an outlying point is found, the test should be repeated. Also, if the resistance curve has
more curvature over a particular range of speeds, runs can be added or substituted in order to fill in
the curve.
• You should take the opportunity to observe wave profiles along the model length (a camera can be
useful for this). Note how they change with speed.
lab1-2008.doc
Brian Veitch, EN4042, Tel: 737-8970, e-mail: bveitch@engr.mun.ca
Engr 5011 Resistance & Propulsion of Ships
Resistance Laboratory: Winter, 2008
Analysis and Reporting
• Use the ITTC 1957 and 78 methods to extrapolate to the total ship resistance and effective power
as a function of ship speed for seawater at 15°C. Use the spreadsheet provided as a guide.
Show the following:
• Tabulate VM, RTM, Fn and RnM, CTM, CFM, (1+k)CFM, CR, CTS, CFS, (1+k)CFS, CA, VS(knots), RTS, PE.
Plot (i) RTS versus VS, (ii) CTM, CFM, and (1+k)CFM against Fn, (iii) CTM, CFM, and (1+k)CFM against
log 10RnM, and (iv) PE against VS(knots). Note that experimental results should be denoted by symbols;
fitted curves and equations should be denoted by lines (without symbols).
• Use Prohaska’s method to determine the form factor. Identify the points deemed useful and show
the plot.
• Use Conn’s method to correct for blockage effects.
• The report should include an introduction, a description of the test facilities and equipment, an
account of the test methods and analysis procedures, and the results with any relevant discussion
and conclusions.
The report and the experiment logbook are to be presented to Dr. Veitch by February 26, 2008.
A model of a fishing boat Marauder, model M455A, will be used. Its principal particulars are given
in the table below. The body plan is shown in the accompanying figure.
Table. Model and ship data
Marauder
5.88
λ
LOA
2.873 m
LBP
2.808 m
B (at waterline)
0.943 m
CB
0.322
CP
0.675
CWP
0.76
Light displacement
T
S
0.345 m
2.689 m2
Loaded displacement
T
S
0.425 m
3.038 m2
lab1-2008.doc
Brian Veitch, EN4042, Tel: 737-8970, e-mail: bveitch@engr.mun.ca