BOAT HANDLING
SAR Crew Manual
Chapter 6
Boat Handling
Commands
Docking/ Undocking Commands
• Let go forward/ aft
•
•
•
•
Let go mooring ropes
forward and aft
All gone forward/aft Mooring ropes let go
All clear forward/aft Mooring ropes are clear
of the water/propellers
Clearance 10 feet There is 10 foot between
the boat at named place
No traffic port/stbd Lookout sees no traffic
to endanger vessel
Manoeuvring Commands
• Steady
• Port/ Starboard
Easy
• Hard a port/stbd
• Port/ Starboard to
000°
Hold this course
Turn gently to port or
starboard
Turn wheel all the way
over to port or starboard
Alter course to port to
or starboard to come to
the specified course
Engine Commands
• Stop
•
•
•
•
Throttles to neutral
immediately
Take way off Use astern to take way off
Full astern
Full astern to take way off
immediately
Maintain
Ahead speed just
steerage
sufficient to maintain heading
Trim up/ Trim Adjust trim tabs for
Down
optimum performance
Personnel Commands
• Secure
Every person on board must get a
secure grip on the boat and then
answer “Secure”. Once everyone
has acknowledged, vessel may
rapidly increase or decrease speed,
or make hard over turn.
• Orders to move peoples around the boat to
change trim of vessel.
Vessel Reporting
• Vessel 20° on port/ starboard bow, beam/
quarter
• Vessel on steady bearing Probably involves
risk of collision
Touch Signals 1
• Stop
• Maintain course
• Slow down
• Come slightly to
port
Tap helmsman on top of
head or helmet
Push in middle of
helmsman’s back
Pull on back of
helmsman’s vest
Tap helmsman’s left
shoulder
Touch Signals 2
• Turn to port
continuously
• Come slightly to
starboard
• Turn to starboard
continuously
Pull on the helmsman’s
left sleeve until desired
heading is reached.
Tap helmsman’s right
shoulder.
Pull on the helmsman’s
right sleeve until desired
heading is reached.
Forces on the Vessel
Forces on the Vessel
• Any vessel is subject to the forces of wind,
sea, swell, tidal and ocean currents.
• It is necessary for the coxswain to understand
how these affect the vessel, and which forces
will dominate.
Wind Forces on the Vessel
• Wind will always be a predominant force on a
vessel, the more wind the more effect it will
have.
• The larger the surface area of a vessel is
above the water, the greater effect wind will
be. This is termed windage.
• Any vessel will move downwind depending on
the amount of windage, this movement being
called “leeway”.
Wind Forces on the Vessel
• The angle a vessel rides to wind should be
known. It is best found out by stopping the
boat clear of land, and note what angle the
boat settles down to in relation to the wind.
• Take the time to test this.
• This knowledge can then be used in all boat
handling situations, such as docking/
undocking operations, recovering a person in
the water or man overboard, etc.
Sea Forces on the Vessel
• Sea is the movement of the surface of the
water by the passage of the wind over the
surface.
• These waves affect boat handling in various
ways, depending upon their height and
relative direction to the boat’s course, and the
boat’s hull form.
Current Forces on the Vessel
• Current, whether from tidal flow or ocean
movement, will affect the boat dependant
upon the underwater shape of the hull.
• This is called set (direction) and drift
(distance).
• The closer the current’s speed is to the speed
of the vessel, the greater will be its relative
effect.
Current Forces on the Vessel
• Learn the effects of current in your area of
operation, in relation to the general ocean
current rate, or the varying rate of the tidal
current with regards to the times of high and
low water, and the type of tide (spring or
neap)
• Spring tides have the greatest rise and fall
(tidal range) therefore the fastest currents,
whilst neaps tides have the lowest rise and
fall, and therefore the slowest tides.
Forces on the Vessel
• Understanding how the combination of wind,
seas, swells, ocean currents, tidal currents
and outflows from rivers interact, and affect
your vessel, will allow you to operate it safer.
Forces on the Vessel
• Tidal rip
Forces on the Vessel
• Gorge conditions
Forces on the Vessel
• Always check the conditions before going
out, and continuously monitor the conditions
whilst out, and be aware if they are
deteriorating.
Forces on the Vessel
• Pay heed to the conditions when underway,
manoeuvring off a distress or when leaving
or approaching a dock, and use them to the
best advantage, so you don’t end up
unnecessarily fighting them.
Vessel Characteristics
Vessel Characteristics
• A displacement hull will always be in the
water, displacing its own weight of water to
float.
• A non displacement hull will be non
immersed but riding across the surface.
Examples are hovercraft, hydrofoils and
RHIBs at speed. All of these will become
displacement hulls when stopped.
• RHIBs are called planing hulls.
Vessel Characteristics
• A displacement hull
Vessel Characteristics
• A non displacement hull
Nautical Terminology
Vessel Terminology
Forward
Towards the bow or forward of a
named point on the vessel
Aft
Towards the stern
Abaft
Behind a named point on the vessel
Aloft
Above the deck or in the rigging
Inboard
Towards the centreline
Outboard Outside the boat or towards
the sides of the boat
Vessel Terminology
Port Side Left side, when facing bow
Starboard side Right side when facing bow
Centreline Line down the middle of the boat
from bow to stern
Beam
Boat at its widest point or out at the
sides of the boat 90° to its
centreline
Athwartships Across from side to side
Vessel Movement
Vessel Movement
Trim
Trim
• Trim is the angle of the hull in reference to
the water surface.
• It may be adjusted by adjusting:
1. the angle of propulsion.
2. weights on board.
Trim
• The angle of propulsion is generally changed
by adjusting the trim ram on the drive mount,
on outboard engines, or trim tabs on
inboards.
• Trimming up increases the angle and drives
the stern down while lifting the bow up.
• Trimming down decreases the angle and
drives the stern up.
Trim
• The ideal trim angle vs power ratio is when
the boat is stable, and has the minimum of
hull surface in the water.
Trim - too high
• If the boat is trimmed up too high, the boat
may porpoise or chine hop.
• Porpoising is when the bow hops up and
down, even in calm water.
• Chine Hopping is when the boat sways from
one side to the other with increasing
frequency.
Trim - too low
• The steering will be sluggish, and the bow
wake will still be at the bow, and the boat will
be pushing a lot of water.
Optimum Trim
• A good trim angle is characterised by
responsive steering, and by the feeling the
boat is floating on a cushion of air.
• At this angle the boat is using less fuel, is
more stable and is going faster.
Propellers
Propellers
Having the correct and undamaged propeller,
will greatly effect the speed, acceleration and
fuel consumption of the engine.
Propeller Parts
Leading Edge
Trailing Edge
Inner Hub
Blade Tip
Outer Hub
Propellers
• Pitch - This is the forward travel measured in
inches in one revolution.
Propellers
• Diameter - This is diameter of the propeller in
inches.
Propellers
• Rake - This is the
amount of degrees the
propeller blades angle
perpendicular to the
propeller hub.
• Most outboards are
about 15°
Propellers
• Rotation - This determines the direction a
propeller revolves around the axis of the
propeller shaft. Rotation is determined by
looking at the propeller from the rear of the
boat.
• A right hand propeller will turn clockwise
therefore moving down to the right hand side.
• A left hand propeller will rotate counterclockwise or down to the left.
Propellers
Manoeuvring
Manoeuvring
• Use fenders, when available
• When mooring with the wind off the dock
approach at a steep angle.
• When mooring with the wind onto the dock,
come up parallel to dock, stop, and drift onto
the dock.
• Protect the stern and the propellers. With
those you can generally get out of a problem
situation.
Manoeuvring
• Whilst outboard engine and stern drives have
a skeg below the propeller, and the casing is
foil shaped at the propeller and above, for
directional stability, the majority of the
steering is from the screw discharge current
thrust.
Manoeuvring
• Directed thrust is used in the following types
of drives
• Jet drives
• Outboard drives
• Inboard/ outboard drives
Manoeuvring Hints 1
• Rig and lead mooring lines and fenders well
in advance of docking.
• Keep enough headway or sternway to
counteract any wind or tide effects.
• Keep bow into predominant wind or current.
• Avoid using too much speed in a confined
space.
• Use short burst of throttle to achieve what is
required.
Manoeuvring Hints 2
• Steering works best with good water flow,
especially on outboards. Use a little throttle.
• Turn the steering to where required, then use
the throttle.
• Know what position the throttles and steering
are in without looking.
• The engine on the outboard of the arc of a
turn provides better thrust than the inboard
engine.
Manoeuvring Hints 3
• Helmsman to give clear instructions audible
to all.
Directed Thrust
• When the drive unit is turned to port or
starboard, the thrust is applied in that
direction.
Twin Engine Directed Thrust
• The outside arc engine
will give the greatest
turning rate for a given
RPM, for both ahead and
astern movements.
Transverse Thrust
• Transverse thrust is the sideways force
generated by propeller blades, acting as
paddle wheels, through the water, creating
side ways motion.
Transverse Thrust
• In twin screw vessels, transverse thrust can
be used to advantage when manoeuvring.
• It is also known as paddle wheel effect.
Transverse Thrust
1. Both propellers going ahead thrust cancels out.
Same applies when both go
astern
2. Port ahead, starboard astern stern swings to port
3. Starboard ahead, port astern stern swings to starboard
1.
2.
3.
Pivot Point
• In the illustration, the pivot
point of the vessel is shown
for its approximate position
when using the starboard
engine ahead and port
astern.
• With vessel moving astern
the pivot point will move aft,
and the bow will move far
more than the stern.
Getting Underway
Getting Underway
• Before starting the engine:
1. Turn on battery power.
2. Lower engines into the water.
3. Check fuel levels.
4. Attach kill switch.
5. Check throttles in neutral, and turn ignition.
6. Set RPMs to warm up speed for defined
time.
Getting Underway
• Always kick the stern off by turning the wheel
towards the dock, and kick the offshore
engine ahead.
• Centre the wheel, and go astern on both
engines away from the dock. This keeps the
propellers clear and uses the pivot point of
the boat to best advantage.
• Once clear of the dock, manoeuvre as
required.
Waterjets
Waterjets
• A waterjet consists of engine driven impellers
mounted in a housing. The intake is in the
bottom of the hull, and the discharge nozzle
is fitted in the transom.
• The cross sectional area of the intake is
much bigger than the discharge nozzle.
• There is no part of the propulsion below the
hull making it suitable for use in shallow
water.
Waterjets
• Vessel control is through the nozzle directed
thrust.
• To move ahead, the thrust comes out of the
transom unimpeded.
• To turn the nozzles pivot to provide a
transverse component, that moves the stern.
• To go astern, a bucket like deflector drops in
front of the nozzle, and directs the thrust
forward.
Waterjets
• When going astern aerated water may be
drawn into the intake, causing a reduction of
thrust.
Pacing
Pacing
• This is the ability to move up on another
vessel proceeding at speed, go alongside,
and hold the vessel there, and then safely
breaking away.
Pacing
• The process is in five parts:
1. The approach
2. Coming alongside
3. Holding alongside
4. Breaking away
5. Getting clear
Pacing
• Stop, Assess, Plan should be carried out
before proceeding into a pacing situation,
although stopping will likely not give the best
appreciation of dangers.
Pacing 1. The approach
• The vessel which is to be paced, maintains
course and speed.
• The vessel pacing makes a course coming
up parallel to the vessel to be paced, and
looks for a section of the flat side of the other
vessel, clear of obstructions and overside
discharges.
Always have escape routes planned.
Pacing 2. Coming alongside
• The vessel pacing now about 20 foot off,
maintains the same speed as the vessel to
be paced, but alters gently toward the side of
the vessel which is to be paced, until its port
or starboard bow touches the starboard or
port side of the other vessel.
• The power may have to be increased, due to
the acceleration of the water around the
paced vessel.
Pacing 3. Holding alongside
• Once alongside the wheel of the pacing
vessel should be kept slightly towards the
side of the paced vessel, and the r.p.m
varied so as to hold the pacing vessel
alongside in the one position.
• On a RHIB, the tube on the bow should be
noticeably compressed.
Pacing 4. Breaking away
• Before breaking away, there must be a good
shoulder check on the outboard side, to
ensure there is clear water to move away
into.
• Keeping the same r.p.m, turn the wheel away
from the side of the paced vessel, so as to
allow a 10 - 15 degree V to form and allow
the vessels to separate.
Pacing 5. Getting clear
• Once the pacing vessel is about 10 to 15 foot
off, manoeuvre as required, taking a round
turn away, watching for and if necessary
keeping clear of the wake of the paced
vessel.
• Do NOT cross ahead of the paced vessel.
Station Keeping
Station Keeping
• This is the ability to keep a vessel in one
place relative to another.
• This may be relative to a fixed point ashore,
or relative to a stationary object such as a
buoy in a tidal current.
Station Keeping
• Stop, Assess, Plan should be carried out
before proceeding into a station-keeping
situation. Items to be considered include:
1. Observe wind, sea, swell, and currents.
2. Observe water colour, and identify shallows,
ledges, and turbulent water.
3. Keep a constant sea watch, looking for
increasing waves, warn the helmsman who
can move away if necessary
Station Keeping
4. Approach slowly, relative to the reference
point.
5. The bow is easier to control when head to
the sea/ swell. Do not get caught beam on.
6. Always have escape routes planned.
Boat Handling
Now go out and practice, practice
and practice some more.