BOAT%20HANDLING

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BOAT HANDLING
SAR Crew Manual Chapter 6
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Boat Handling
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Commands
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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

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Manoeuvring Commands

• Steady Hold this course
• Port/ Starboard Turn gently to port or
  Easy starboard
• Hard a port/stbd Turn wheel all the way over
  to port or starboard
• Port/ Starboard to Alter course to port to 000
  or starboard to come to the specified
  course

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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

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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.

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Vessel Reporting

• Vessel 20 on port/ starboard bow, beam/ quarter
• Vessel on steady bearing Probably involves risk
  of collision

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Touch Signals 1

• Stop Tap helmsman on top of head or helmet
• Maintain course Push in middle of
  helmsmans back
• Slow down Pull on back of helmsmans vest
• Come slightly to Tap helmsmans left
  port shoulder

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Touch Signals 2

• Turn to port Pull on the helmsmans
  continuously left sleeve until desired
  heading is reached.
• Come slightly to Tap helmsmans right
  starboard shoulder.
• Turn to starboard Pull on the helmsmans
  continuously right sleeve until desired
  heading is reached.

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Forces on the Vessel
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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.

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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.

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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.

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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 boats course, and the boats
  hull form.

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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 currents speed is to the speed of
  the vessel, the greater will be its relative
  effect.

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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.

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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.

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Forces on the Vessel

• Tidal rip

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Forces on the Vessel

• Gorge conditions

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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.

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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 dont end up unnecessarily
  fighting them.

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Vessel Characteristics
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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.

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Vessel Characteristics

• A displacement hull

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Vessel Characteristics

• A non displacement hull

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Nautical Terminology
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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

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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

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Vessel Movement
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Vessel Movement
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Trim
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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.

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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.

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Trim

• The ideal trim angle vs power ratio is when the
  boat is stable, and has the minimum of hull
  surface in the water.

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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.

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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.

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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.

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Propellers
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Propellers

• Having the correct and undamaged propeller, will
  greatly effect the speed, acceleration and fuel
  consumption of the engine.

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Propeller Parts
Leading Edge
Trailing Edge
Inner Hub
Blade Tip
Outer Hub
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Propellers

• Pitch - This is the forward travel measured in
  inches in one revolution.

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Propellers

• Diameter - This is diameter of the propeller in
  inches.

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Propellers

• Rake - This is the amount of degrees the
  propeller blades angle perpendicular to the
  propeller hub.
• Most outboards are about 15

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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
  counter-clockwise or down to the left.

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Propellers
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Manoeuvring
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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.

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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.

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Manoeuvring

• Directed thrust is used in the following types of
  drives
• Jet drives
• Outboard drives
• Inboard/ outboard drives

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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.

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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.

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Manoeuvring Hints 3

• Helmsman to give clear instructions audible to
  all.

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Directed Thrust

• When the drive unit is turned to port or
  starboard, the thrust is applied in that
  direction.

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Twin Engine Directed Thrust

• The outside arc engine will give the greatest
  turning rate for a given RPM, for both ahead and
  astern movements.

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Transverse Thrust

• Transverse thrust is the sideways force generated
  by propeller blades, acting as paddle wheels,
  through the water, creating side ways motion.

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Transverse Thrust

• In twin screw vessels, transverse thrust can be
  used to advantage when manoeuvring.
• It is also known as paddle wheel effect.

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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.
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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.

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Getting Underway
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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.

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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.

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Waterjets
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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.

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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.

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Waterjets

• When going astern aerated water may be drawn into
  the intake, causing a reduction of thrust.

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Pacing
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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.

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Pacing

• The process is in five parts
• 1. The approach
• 2. Coming alongside
• 3. Holding alongside
• 4. Breaking away
• 5. Getting clear

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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.

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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.

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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.

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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.

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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.

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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.

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Station Keeping
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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.

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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

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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.

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Boat Handling

• Now go out and practice, practice and practice
  some more.