Coxswain Study Guide
(18’ Zodiac Cutter Boat- Medium)
Created by BM3 Carter
Responsibilities of the coxswain
A.) conduct and safety of the crew and passengers
B.)the safe navigation and operation of the vessel
C.)completion of the mission or sortie
D.)Protection of life and property
E.)enforcement of laws, treaties and regulations
Crew Fatigue Chart
Boat size
40' and
above
Maximum Underway Hours
Seas >4
Seas <4
HWX
Rest
Required
10
8
6
8
30'-39'
8
6
N/A
8
Less than 30'
8
6
N/A
8
Boat Characteristics
A.) Hull-Glass Reinforced Plastic
B.) Console- Glass Reinforced Plastic
C.) Length of Boat overall- 18.33’
D.) Length of rigid hull- 15.42’
E.) Beam- 7.08’
F.) Freeboard aft- 13 inches
G.) Freeboard amidship- 19 inches
H.) Weight (unloaded)- 1640 lbs
I.) Draft- 13 inches
J.) Sponson Material- 1100 dtx hypolon
K.) Number of chambers- 3
L.) Tube Diameter- 19 inches
M.) Person Capacity- 8 Adults + 0 children
N.) Max Horsepower- 90
O.) Min. Horsepower to plane- 50
Deck Equipment onboard
-Anchor- Danforth Anchor
-Anchor Line- 100’ of line
-Dry Chemical Extinguisher
-Bell
-First Aid Kit
-Tool Kit
-Sponson repair kit
-Handheld GPS
-Bailer
-6’ boat hook-retractable
-2 kill switches
Installed Electronics onboard
-VHF-FM radio
-GPS
-combined running lights
-L/E Lights
-White mast light
- Battery
-Battery Switch
Warning Signs of an Unstable Boat
-Determine if other boat is listing: Observe Vessel to determine if it is sitting straight up and down or if
it is leaning over to one side or the other.
-Determine if other boat is riding high or low in the water: Observe vessel and see if it is sitting high in
the water or if it is sitting lower then it is designed too.
-Determine if other boat is down by the bow or the stern: Observe vessel and see if it is sitting low in
the stern or if its bow is sitting low in the water.
-Determine wind and sea conditions: Observe the direction and strength of the wind and the currents
and how they will affect the vessel. Keep this in mind when doing your approach to board
vessel.
-Compare own boat’s righting moment with other vessels in the area: Observe your vessel and when it
reaches its righting moment and observe other vessel to see if it is consistent with each roll.
Remember that different vessels will have different righting moments depending on time and
vessel construction.
-Determine if other boat is damaged: Observe vessel and see if there is any noticeable damage to the
vessel which could endanger the crew or the boarding party.
-State the causes and effects of the following:
A.) Free Surface Effect- When loose water shifts from side to side or fore to aft due to speed
changes, turning or wave action, the vessel’s righting moment is altered which could
cause the vessel to capsize.
B.) Downflooding- This is the entry of water into a vessel causing progressive flooding which will
negatively affect stability. This normally is a result of the crew failing to maintain water
tight integrity.
C.) Topside Icing- Ice on the vessel can cause the vessel’s displacement to change and the
center of gravity to rise which could cause the vessel to heel and become unstable. This
could result in the vessel being more likely to capsize.
Forces that Affect Boat Handling
-State the two types of stability:
-Longitudinal
-Transverse
- “Force of Buoyancy”: Upward force of water displaced by the hull. This force keeps the vessel afloat.
- “Righting Moment”: The force causing a vessel to react against a roll and return to an even keel.
- “Set”: Direction of forces and include winds, currents and the sea condition. Expressed in degrees.
- “Drift”: The strength of the set and is expressed in knots.
- Effect of an ebb tide on a bar or entrance: Builds more intense seas then the incoming or flood
current. The rush of water out against the incoming ground swell slows the wave speed and
steepens the swell prematurely.
- Effect of running with the current: Vessel is going to have less maneuverability and there is going to
need to be caution with amount of speed and rudder used.
-Effect of running against the current: Vessel is going to have more maneuverability but the vessel is
going to have to work harder to push through it.
- Effects of Leeway: Locals winds blowing objects across the surface of the water. This affect vessels by
pushing against them in the same direction as the wind. This especially needs to be considered
on vessels that have a lot of exposed superstructure.
- Effects of wind blowing out an entrance: Depending on size of vessel, will create an against the
current situation like what is experienced in a river.
- Causes of Cavitations: Air bubbles created at the tip of the blades of the propeller due to a partial
vacuum being created because of high speeds.
- Effects of Slip: The distance lost after one complete rotation of the propeller. (Pitch)
- Effects of dynamic Propeller Thrust: The natural effects that the environment will cause on the thrust
of the propeller.
- Unequal Blade Thrust: Due to the angle of the propeller shaft, the effective pitch angle is different for
ascending and descending propeller blades. This creates more thrust resulting in more speed.
- Effects of “side Force”: The effects of side force is that depending on how the propeller is set up and
whether there are one or two propellers. The stern of the boat will tend to move to the right or
left depending on the spin of the propeller when making sternway.
Basic Principles of Boat Handling
- Reaction of the boat with sternway on and the rudder amidships: In an ideal world the vessel would
go directly astern, but you must take into account external forces such as current, wind and side
force. This will result in the vessel not going astern in a straight line.
- Reaction of the boat with sternway on and the rudder left: The vessel’s stern is going to swing to port
while the bow swings to starboard. The amount of thrust used is determined by the external
forces and what is working against you.
- Reaction of the boat with headway on and the rudder left: The vessel’s bow will turn to port while the
stern will turn to starboard
- Reaction of the boat with headway on and the rudder right: The vessel’s bow will turn to starboard
while the stern will turn to port.
- Reaction of the boat when commencing forward motion from no way-on: The throttle should be
moved up gradually and firmly. Due to side force the stern will want to move to starboard. You
can counteract this by turning the helm slightly to starboard.
- Reaction of a twin screw boat when the port screw is placed ahead and the starboard screw in
reverse: Vessel is going to pivot to starboard.
- Reaction of a twin screw boat with the port screw ahead, the starboard screw in reverse, and the
rudder to the right: Vessel will turn to Starboard sharply.
- Reaction of a twin screw boat with the port screw ahead, the starboard screw in reverse, and the
rudders to the left: Vessel will turn to starboard slowly. The port screw will be trying to push the bow to
starboard, the starboard screw will be trying to push the stern to port while the rudder is trying
to direct the ship forward to port.
Operational Characteristics and Limitations of the Boat
-Maximum speed in knots: 26 knots, trimmed down in flat seas.
-Most economical cruising RPMs: 1/3 of the maximum RPM, so about 1800 rpm.
- Maximum range of the boat at cruising RPMs in nautical Miles: N/A, should never be out of sight of
cutter.
- Minimum crew size of the boat: 2 (1 coxswain + 1 Crewmen)
- Maximum following seas in which boat can operate: 6 feet
- Maximum wind speed boat can operate in: 30 knots
- Maximum size vessel boat can tow: Vessel does not tow.
- Can boat be used to break ice: No, vessel is not designed to break ice.
- Can it operate in breaking surf or bar conditions: No, vessel is not designed for breaking surf.
- Maximum size surf boat can take without capsizing: None
Characteristics of the Components and Accessories of the Boat’s Propulsion
System
-Model of the engine: Honda
- Horsepower of the engine: 90
- Direction of shaft rotation for engine: Clockwise
-Maximum shaft RPM for each engine: 3000 RPMS
- Type of fuel used: Gasoline
- Maximum fuel capacity: 2-6 gallon fuel tanks. (but could be more if the crew desires)
- Capacity of lube oil system: 2 Quarts
- Type of cooling system used on the engine: Sea Water
- Diameter of the propeller in inches: 13 inches
- Number of blades on propeller: 3 Blades
Energize the Electrical and Electronic systems on the boat
- Ensure all power switches are turned on: All power switches are located on the right side of the
console underneath the helm.
- Ensure breaker is turned on: Behind the seat there is a switch that must be turned to “On” to get
power to vessel.
Conduct a Pre-start Check-off for the boat
- Check bilges for excessive water or fuel: Check stern of vessel to make sure boat plug is put in and
that fuel system is intact.
- Locate dipstick and check engine and gear oil levels: Take off cover to engine and the dipstick is there
on top.
- Check engine coolant level: Engine is cooled by intake of salt water into the system. Make sure the
inlet vents are free of debris.
Start the boat
- Ensure that main breaker and general lighting systems are energized: Upon entering the vessel,
reach down behind the seat and turn on switch to turn on power. Then ensure that all switches
for necessary navigation lights are energized.
- Place throttles in neutral: Shake throttle to ensure it is in the middle/neutral position.
- Start the vessel: Ensure that the kill switch is installed. That the throttle is in neutral. Turn the key to
start the vessel. You should see overboard discharge out of the outboard along with the RPM’s
on the gauge level out.
- If vessel does not start: Ensure kill switch is engaged, check to see if throttle is in neutral. Make sure
battery is turned on. Check the fuel bulb primer to make sure there is fuel in the system. Check
system intact on outboard. Pull choke out to start engine. Once it starts and idles for a minute,
push choke back in before departing from the cutter.
Conduct a Pre-Underway Check-off for the boat
- Conduct daily boat checks: Boat checks are supposed to be done every morning by sunrise by one
bridge Watchstander and one engineering Watchstander. The deck side checks to make sure
Sponson is inflated, all necessary gear is onboard, all mooring lines are attached and that the
painter is installed. Check to ensure Kill switches, fire extinguisher and bell are working as well.
- Brief crew on mission: Brief crew on situation and what is to be expected. Use the facts. If there is any
confusion, make sure to clear it up before getting underway. Make sure the crew participates
and asks questions. Make sure crew has all required gear and required PPE.
- Secure boat is secure for sea: Make sure all missile hazards and all loose gear that you do not want to
go overboard is secured down somehow.
- Ensure all equipment needed for mission is onboard: For Operations out here all required gear
onboard will include extra PFDs, the M4, Boat Crew Helmets, handheld GPS, First Aid Kit,
Sponson Repair kit, Tool Kit, water, Hand pump for Sponson, dewatering pump, bailer and
Anchor assembly.
- Ensure crewmembers are wearing proper PFD: Boat Crew will wear fully complimented gun belt with
peci’s. A Marsir’s vest will be worn as well with sufficient foam to increase buoyancy. Pyro bags
are worn around the waist by two members. Helmets are required if you will be in boat when
the crane is being used. Each boat crew member will have a M9 and the crewman will have a
M4 with 3 magazines each in the standard method of carry.
-Check Engineering Report: Ensure during the boat brief that there are no major casualties with the
small boat.
- Test electronic equipment: Turn on radio and turn on GPS and ensure they are working. Turn on
Navigation lights.
Maneuver in Rivers
- Define bank cushion and its effects: In narrow rivers, a vessel moving through the water will cause the
“wedge” of water between the bow and the nearer bank to build up higher then on the other
side.
- Define bank suction and its effects: As the stern moves along, screw suction of water to “fill-in”
where the boat was. This will cause the stern to move towards the shore.
- Define “Hug the Point”: As the channel begins to bend and the boat moves from the bank, less
rudder will be necessary. This condition is a signal that it is time to begin the turn. However,
slack water or eddies may be around the bend, making it difficult to prevent a sheer toward the
near bank, especially in shallow water. The current under the quarter may affect the stern, and
result in an increase in sheer. To correct for this, you should apply additional power and rudder
to steer back towards the center of the channel, keeping the stern in the middle of the channel.
Visual aid below.
- Define “Stay in the Bend”: Staying in the bend is a turn in the bend away from the point that takes
precise timing. If done too late, the boat may ground on the bank in the bend. If done too soon,
there is extreme danger that a strong and sudden sheer will occur. The bank suction on one
quarter combines with the current on the other quarter to give the boat the sheer. Also, the
bank cushion under the bow will increase the sheer. Again, to correct for this situation,
additional power and rudder should be applied to steer back towards the center of the channel.
Visual aid below.
- Define “Proceed on the Bend Side, Middle of the Channel”: Approaching the turn steering a
course toward the bend side of the middle of the channel is the safest method when the current
is following. By doing this, the boat avoids any eddies under the point and the increase in
currents in the bend. The operator can also use the force of the current against the quarter to
help in the turn. A following current will force a boat toward the bend side; consequently, the
turn should be commenced early in the bend. Additional power and rudder should be applied as
needed to stay in the middle of the channel. Visual Aid below.
Identify Heavy Weather Terms
-State definition of “surf”: Several breakers in a continuous line.
- Discuss effects of wind on waves: Wind will affect direction and height of waves. The farther the wave
has to travel through a wind the higher the wave will be. Thus the fetch is directly related to
wave height and direction.
- Determine wave height using height of eye on freeboard: With the boat in the trough and on a
level and even keel, any wave that obscures the horizon is greater than the height of a person’s
eye. The height of eye on a 47' MLB is about 14 feet while seated at the helm or standing on the
open bridge. One can also compare a wave to the deck edge or a structure such as the handrail.
The wave face is observed while bowing into it and in the trough on an even keel. This is also
generally the best method for judging surf.
- Determine wave height by comparing with floating structures: This technique is most useful
when observing from land, but may be applied while underway. If the freeboard of a buoy is
known to be 13 feet, that information can be used to determine the height of the waves passing
it. A buoy can also be used to determine the wave period. One can observe a vessel underway
and by estimating the freeboard of the vessel and observing its motions on the water, he or she
can gain a fair estimate of the seas in which it is operating.
- Determine wave height by comparing with fixed structures: Observation of waves as they
pass a
fixed structure, such as a break-wall, jetty, or pier, can be very accurate and can also provide
wave period.
- Identify types of breaking waves: There are three types of breaking waves. Plunging, Spilling and
Surging waves.
- Identify the following:
- Window: A window is an area where the waves have momentarily stopped breaking, opening
up a safer area of operation for your boat. Windows often form in the area of aerated
water where a large set of waves has just finished breaking. The window may remain for
a long time or may begin breaking again almost immediately. It is preferable to operate
the boat in the windows whenever possible
- Wave Saddles: The “saddle” is the lowest part of a wave, bordered on both sides by higher
ones. Often it is a small, unbroken section of a wave that is breaking. It is preferable to
drive a boat in the saddles if possible, thus avoiding the white water. While saddles are
very useful, they must be watched carefully, because they easily turn into “close-outs.”
- Close Outs: “Closeouts” occur when a wave breaks from the ends toward the middle, or two
waves break towards each other. The middle may look like a good saddle, but can
quickly turn into whitewater. Closeouts should be avoided because they can create
more energy than a single break.
- High and low side of a wave: The “high side” is defined as the section of a wave which
carries the most potential energy. It may be the part that is still building towards
breaking point, or it may be the part which has already broken. The “low side” is where
the least potential energy exists and represents the safest direction to turn when facing
the wave/swell. These high and low sides often change rapidly, and the ability to
quickly navigate the high and low sides is a critical skill for surf operations. Visual Aid
below.
Anchoring
-Define Swing Circle: As the wind or water current changes direction, the boat will swing about its
anchor. This swing circle is centered on the position of the anchor. The swing circle’s radius is
equal to the boat’s length plus the length of anchor line/chain that has veered (Example: 40-foot
boat + 150 feet of anchor line out = 190-foot swing circle). The swing circle must be clear of
other vessels and underwater obstructions. When checking the boat’s position, it should fall
inside the swing circle.
-What scope is used: On our small boat we will typically use a 3 to 5 or 5 to 1 ratio. We rarely ever
anchor.
-What do you do if anchor is fouled: If the anchor refuses to break free, perform the following
procedures:
-Step 1: Snub the anchor line around the forward bitt or cleat and advance the boat a
few feet.
-Step 2: Sometime even this will not free the anchor, and the operator should run in a
wide circle, slowly, to change the angle of pull.
-Step 3: Take extreme care to ensure the anchor line does not tangle in the screws
during this operation.
Another way to break out an anchor is with a “trip line” (if one was rigged before anchoring). A
trip line is a line strong enough to stand the pull of a snagged anchor (a 3/8-inch line is a typical
size). Perform the following procedures if a trip line is needed:
-Step 1: Attach one end of the trip line to the crown of the anchor (some anchors have a
hole for this purpose). The trip line should be long enough to reach the surface in
normal anchoring waters, with allowance for tidal changes.
-Step 2: Secure the other end of the trip line to a float that can be retrieved with a boat
hook.
-Step 3: If the anchor does not trip in the normal manner, pick up the trip line and haul
the anchor up from the crown.
Besides helping recover a fouled anchor, a trip line helps determine where the anchor is in
relation to the vessel. This may help prevent other boaters from anchoring in the area as well as
help make the approach back to the anchor during recovery.
Rules of the road
-Pass the DWO Examination: Study NavRules Book to take examination.
Identify Navigational Publications
- What is the Coast Pilot: This manual contains sailing directions between points in its respective
area, including recommended courses and distances. Channels with their controlling depths and
all dangers and obstructions are fully described. Harbors and anchorages are listed with
information on those points at which facilities are available for boat supplies and marine repairs.
Information on canals, bridges, docks, and more, is included.
-What is the Light List: A United States Coast Guard publication (multiple volumes) that gives
detailed information on aids to navigation.
-What is a local notice to mariners: A written document issued by each U.S. Coast Guard District to
disseminate important information affecting aids to navigation, dredging, marine construction,
special marine activities, and bridge construction on the waterways with that district.
-What is a tide table: Daily predictions of the height of water, at almost any place, at any given time,
and are published annually in four volumes. Instructions for using the tables are provided within
the publication.
-What is a tidal current table: Provides the times of maximum flood and ebb currents, and times of
the two slack waters when current direction reverses. They also tell the predicted strength of
the current in knots. The time of slack water does not correspond to times of high and low tide.
The tide tables cannot be used for current predictions. The tables are published in two volumes.
Instructions for using the tables are provided within the publication.
-What are the nautical charts used for our AOR: 62453; 62413; 62412; 62530; 62541; 62584
-What is Chart No. 1: Standardized list of chart symbols and abbreviations for charts.
Distance, Speed and Time
-State the importance of computing distance, speed and time: Being able to solve basic Distance, speed
and time problems will enable you to determine course corrections and do necessary chart work
used in planning the mission or sortie.
-State units of measurements and formulas for distance, speed and time: Distance is measured in
Nautical Miles, Speed is measured in Knots and Time is measured in minutes
-What are the three formulas for solving for distance, speed or time:
-D=S x T/60
-S= 60D/T
-T= 60D/S
-What is the 3-minute rule: A tool used to solve for distance or speed in a 3 minute time frame. For
Example: If you are driving 13 knots, how far would you go in 3 minutes? The answer would be
1300 yards. You must move the decimal point over to the right two spots and it is measured in
yards, not Nautical Miles. To find speed, if you went 1500 yards in 3 minutes, how fast are you
going? The answer would be 15 knots.
-What is the 6 minute rule: Another tool used to solve for distance or speed in a 6 minute time frame.
For Example, if you are driving 20 knots, how far would you go in 6 minutes? The answer is 2.0
Nautical Miles. It can also be used to find speed. If you travel 1.0 Nautical Miles in 6 minutes
then how fast are you going? The answer is 10 knots. Depending on whether you are solving for
speed or distance, you must move the decimal place to the right or left 1 spot.
Man Overboard
-What are the coxswain’s responsibility during a man overboard: Once the alarm has been
sounded, the coxswain has several tasks to complete in order to successfully recover the PIW.
Though a quick recovery is preferred, at times it is better to slow down, assess the situation, and
ensure everything is done properly the first time. Not every MOB/PIW recovery is the same. It is
always better to make a correct approach slowly and recover the person on the first attempt
rather than an incorrect fast approach resulting in the need for a second try. There is no single
correct order in which the steps below should be executed. Everything depends on the situation
at hand. Starting a turn to maneuver back to the PIW is a common first step, but if boat traffic in
the area is heavy, turning the vessel might endanger others. Each task is important in its own
way and needs to be conducted to ensure a successful recovery.
-Maneuvers used by coxswain during man overboard: If someone falls overboard, the boat may
have to be maneuvered for a pickup. In most cases, it starts by turning in the same
direction the person fell overboard. Turning towards the same side the person fell
overboard will “kick” the stern away preventing the propellers from injuring the PIW. If the
person falls off the bow, the turn should be in either direction to kick the stern clear. If the
person falls off the stern, in some cases, the eddy current located off the transom can hold the
PIW tight against the stern. Applying additional power while turning sharply to either port or
starboard will push the PIW clear. In some cases, turning the boat is not possible due to vessel
traffic or a narrow channel. In these cases, slowing down and stopping are other options. Once
the boat has stopped, the PIW may swim back towards the boat for recovery or after slowing to
bare steerageway, spin the boat around and recover the PIW. An increase in speed is not
necessary during the turn. Recovering the PIW as soon as possible is important, but sometimes
an increase in speed by the coxswain will catch the remaining crewmembers off guard and
possibly eject them from the boat. If operating at high speed when the MOB takes place, it
might be best to slow down before starting a maneuver. The coxswain should carry out the turn
at a safe speed to ensure a more stable platform for the recovery crew.
-What is a windward approach: The windward approach is performed with the wind coming from
behind the boat, when the person overboard is in a confined space, and a leeward approach is
impossible. However, a situation where the boat cannot turn into the wind due to
superstructure or bow sail area should be avoided.
-What is a leeward approach: The leeward approach is performed with the bow facing into the
greatest force of oncoming resistance at the time of pickup using the following procedures. This
may be the wind, current, seas, or any combination of the three. There are times when the wind
and current are from different directions.
-What is a destroyer Turn: Except in a narrow channel, the coxswain should make the turn to the
side that the person fell overboard. This will kick the stern of the boat away from the person
preventing injury. This maneuver can be modified for use by twin-propeller boats. Twinpropeller boats are pivoted by putting one engine ahead and the other in reverse. With a singlepropeller boat, the rudder should be placed hard over and additional power applied, if
conditions permit.
-What is an Anderson Turn: An advantage of the Anderson turn is that it is the fastest recovery
method. A disadvantage is that it is not meant for use by a single propeller boat.
-What is a race track turn: The final straight leg approach of the race track turn helps for a more
calculable approach.
Basic Engineering Casualty Control Exercises (BECCE)
-Fire on the outboard engine: If there is a fire on the outboard, secure it. Try to put the bow into the
wind. Grab the fire extinguisher out of the forward compartment and spray into the vents on
the outboard. Do not take the cover off. If necessary throw the gasoline tanks over the side of
the small boat.
-Loss of Steering (cable/hydraulic): Check system intact. Make sure that there is fluid in the steering
system by checking the reservoir on top of the helm.
-Loss of Steering (Jammed Rudder): Check system intact. Make sure hydraulics are attached and
working properly. Check hydraulic fluid.
-Accidental grounding: Check to make sure you are not taking on water. Call the cutter and let them
know your position and let them know you are grounded. Check the tides and see if the tides
are coming in or going out. DO NOT LEAVE THE VESSEL. Do not try to back out using the
propeller because it will compact sand underneath the hull of the small boat making it harder to
get out.
-Collision with Submerged Object: Check to see if you are taking on water anywhere. If you are treat
as needed to get the vessel back to the cutter or so the cutter can come to you. Check to make
sure the lower unit of the engine is still intact.
-Loss of Main Engine Lube Oil Pressure: Check system intact. Put oil into engine if you need to.
- Loss of Control of Engine RPMs: Use the kill switch to kill the engine if you cannot secure it
regularly.
-General starting difficulties including engine not starting and emergency starting procedures:
Check to see if the battery is switched on. Make sure the kill switch is in. Make sure the
fuel is primed. Make sure the throttle is in neutral Try to pull the choke out and start it
like that. If it starts, let it run for a few minutes then secure it before getting underway.
-Propeller damage and excessive cavitations: If you have enough blades try to make it at a slow
speed back to the cutter.
-Immersed outboard: Not much you can do but get the small boat back to the cutter and dry it out.
-Loss of electrical power: Check to make sure the battery is connected properly and that switch is
turned on. Check system intact.
Towing and Salvage
State General Towing Safety Precautions
-What are the precautions regarding removal of personnel from disabled boats: You need to
make sure that all personnel onboard are wearing life jackets and that the vessel is stable
enough for you to come alongside safely to disembark passengers.
-What are the policies regarding wearing of PFDs by persons onboard the disabled boats:
Everyone onboard should be wearing life jackets if they are out on deck.
-What are the precautions regarding the throwing of heaving lines: You need to make sure that
the vessel is ready to receive heaving line. Throw the heaving line over the bow of the vessel
and make sure line is tended so that it does not fall in the water and get caught in the screws of
either vessel.
-What is the policy for establishing and maintaining communications: Positive communication
must be kept with the people onboard and constant communication needs to be kept with any
personnel left on the vessel while it is being towed. Stay calm and speak in a calm and relaxed
voice to avoid upsetting the passengers any more than they already are.
-What is the policy regarding personnel around the towline: Everyone working around the
towline needs to be wearing the proper PPE. Life jackets, eye protection and hard hats are
essential to maintaining a safe environment. Only essential personnel should be around the
towline and NEVER straddle or step over a tow line.
-What are the precautions regarding the breaking strength of shackles used: Only use shackles
that are weighted for that specific evolution. If needed distribute the weight evenly amongst
several shackles to prevent breaking any of them.
-What are the precautions regarding the towed boat’s hull capability and speed: When towing
a vessel you must never travel any faster than the boat’s hull capability. This can be calculated
using the formula:
S = Maximum towing speed (hull design speed)
Ss = Maximum safe towing speed
Lw = Square root of length at waterline
S = 1.34 x Lw
Ss = S - (10% x S) a 10% reduction in the maximum towing speed
The Principle Forces that affect Towing a boat
-What are the causes and effects of static forces: Static force is constant or internal forces placed on a
vessel. Static forces are caused by placement of weight within the hull. Adding weight on one
side of a boat’s centerline or above its center of gravity usually reduces stability. Flooding or
grounding a boat makes it susceptible to static forces which may adversely affect stability. Static
forces cause a towed vessel to resist motion. The displacement or mass of a towed vessel
determines the amount of force working against the vessel. The assisting vessel must overcome
these forces before the towed vessel moves. Inertia and the moment of inertia are two different
properties of static forces that cause resistance in towing vessels.
-What are the types, causes and effects of dynamic forces: Dynamic forces are caused by actions
outside the hull such as wind and waves. Strong gusts of wind or heavy seas, especially in
shallow water, may build up a dangerous sea tending to capsize a boat. Dynamic forces occur
once the towed vessel is moving. They are based on the towed vessel’s characteristics (shape,
displacement, arrangement, rigging), the motion caused by the towing vessel, and the effects of
waves and wind.
-What is the cause of towline strain: The cause of strain on the towline is shock
loading the line. When the line is tight it puts undue stress on the line and
bitts or/and cleats.
-What is the cause and effect of shock load: The cause of shock loading is when forces acting on the
line change irregularly and quickly putting a lot of tension on the line really fast.
-What is the effect of lengthening the towline has on shock load: A longer towline reduces the
effect of shock-loading in two ways. The weight of the line causes a dip in the line called
catenary. The more line out, the greater the catenary. When tension increases, energy from
shock-loading is spent on “flattening out” the catenary before it is transferred through the rest
of the rig and fittings. The second benefit of a longer towline is more stretch length. Depending
on the type of towline, another 50’ of towline will give 5’-20’ more stretch to act as a shock-load
absorber. Remember to lengthen the towline enough to keep the vessels in step and minimize
the shock-load source.
Inspection of Towline and Associated Hardware
-Inspect the towline and state the warning signs for wear or defective condition: Inspect
towlines on a daily basis for cuts, chaffing, flattening, fusing, snags and hardening. If any of
these conditions are met, the towline should not be used as a towline.
-Inspect the double-braided bridles and state the warning signs for wear or defective
condition: Crewmembers should inspect pendants and bridles on a regular basis to detect damage and
to ensure bridle leg lengths are equal.
-Inspect the shackles and kicker/skiff hook and state the warning signs for defective
condition: Inspect shackles and kicker/skiff hook for rust or cracks. Any weak points on the gear and
the gear should be not used and replaced.
-Inspect wire rope bridles and state the warning signs for wear or defective condition:
Wire rope bridles should be inspected for broken wires, fish hooks, kinks, worn or corroded
portions, and crushed or flattened sections.
-Inspect bitts, cleats, chocks, and the towline storage reel and state the warning signs for
defective condition: Check for cracks, fractures, rust, corrosion, wood rot, fiberglass core softening or
delamination. Inspect surfaces that are normally hidden from view , particularly backing plates
and under-deck fittings. Tow bars are subject to high vibration and may loosen or cause stress
fractures around their foundations. Ensure smooth working surfaces are kept free from paint
and relieve any surface roughness. A smooth working surface reduces wear, friction and chaffing
gear.
Law Enforcement, Homeland Security and Defense Operations
-Authority and Jurisdiction: Authority is a governments legal ability to act. Out here we are acting
under Iraqi authority to board and enforce Iraqi laws and regulations. Jurisdiction is based on 3
elements substantive law, Vessel status/flag and location. Substantive law is one that prohibits
certain action or requires affirmative conduct. Vessel status/flag is the nationality of that vessel.
The nationality of the vessel will determine if you are able to board the vessel. Location is
determined by if it is in an area where you are authorized to board. In Iraqi territorial waters we
can board vessels if Iraq approves.
- Use of Force against Non-Compliant Vessels: There are 5 steps for Use of force against a NonCompliant Vessel. Step 1 is officers presence which includes blue lights, sirens and using loud
hailers. Step 2 is shouldering, blocking the wind from sails and using nets and lines to trap the
screws of vessel. Step 3 is Less than lethal weapons which include the fin-stabilizing slugs. Step 4
is warning/disabling shots to vessels engine compartments and across the bow of the vessel.
Step 5 is destructive fire where the vessel will be destroyed.
-Less then Lethal Delivery Systems: Less than Lethal delivery systems include fin-stabilizing slugs and
Rubber slugs.