- Slides: 80
BOAT HANDLING SAR Crew Manual Chapter 6
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 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 • 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
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
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 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.
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 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 swings to port 3. Starboard ahead, port astern 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 • 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 • 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 • 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 • 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.