Motor Cruiser Handling for the Power ICC

Prerequisites

You should already know basic boat terminology, the rules of the road at roughly Day Skipper level, and the knots used for mooring (bowline, cleat hitch, round turn and two half hitches). For the power category of the ICC you must show the assessor that you can handle a motor boat safely at low speed, berth and leave, recover a man overboard, and carry out basic engine checks. In the UK the RYA Powerboat Level 2 certificate, or a practical ICC assessment at an RYA centre, covers this. This lesson concentrates on displacement and semi-displacement motor cruisers of the kind you are likely to charter on rivers, canals and coasts, with notes on fast planing boats where they differ.

Learning Objectives

By the end of this lesson you should be able to:

• Carry out pre-start engine checks and start and stop the engine safely, including the use of a kill cord.
• Explain prop walk, and use it when berthing and turning.
• Explain how a single-screw and a twin-screw boat steer, and the role of the pivot point.
• Allow for the effect of wind on a high-sided motor cruiser.
• Turn a single-screw boat in a confined space, and turn a twin-screw boat in its own length.
• Come alongside and leave a berth in different wind conditions.
• Recover a man overboard under power.

Before you start: engine checks

A motor cruiser has no sails to fall back on. If the engine stops in a lock approach or a busy channel, you are in trouble, so engine checks matter more than on a yacht.

Pre-start checks (WOBBLE)

A common memory aid is WOBBLE:

Also check fuel quantity (use the one-third rule: one third out, one third back, one third reserve), that the propeller and rudder are clear of ropes and weed, the steering moves freely, the gear lever is in neutral, and the engine space ventilation or blower on a petrol boat has run for several minutes before starting.

Starting and stopping

1. Gear lever in neutral. Most controls will not start in gear.
2. On a petrol engine, run the blower first to clear fumes.
3. Turn the key or press the start button. On a diesel, preheat with the glow plugs if needed.
4. As soon as it fires, check that cooling water is coming out of the exhaust (or the telltale). No water means stop the engine at once and find out why: usually a closed seacock or a blocked strainer.
5. Check oil pressure and charging lights go out, and listen for unusual noises.
6. To stop: neutral, let it idle for a minute to cool, then stop with the key or the stop control.

The kill cord

Fast boats, RIBs and boats with outboards usually have an engine kill cord: a lanyard clipped to the helmsman and to a switch on the console. If the helmsman falls overboard or is thrown from the helm, the engine stops. Without it, a driverless boat can circle and run down the person in the water.

• Wear it at all times when the engine is running, attached round the leg or to a lifejacket, not to a bag or the wheel.
• Check it works before setting off: start the engine, pull the cord, and confirm the engine stops.
• Carry a spare, so the boat can be restarted if the helmsman goes overboard with the cord.
• Keep it short enough to work: the cord should pull before you are far from the helm.

Many displacement cruisers do not have a kill cord. If yours does, use it.

How a motor boat steers

Rudder and propeller

A propeller pushes water aft when going ahead. On an inboard boat with a rudder, the rudder sits in that flow, so it works even at low speed if you give a burst of power. This is called prop wash over the rudder. Going astern, the propeller pulls water forward past the hull, so the rudder has almost no flow over it until the boat is moving astern at some speed. As a result:

• Ahead, a boat steers well, even at low speed, with a short burst of power.
• Astern, steering is poor until you build speed, and the bow is pushed by the wind.

On an outboard or outdrive, the whole drive turns. The thrust itself steers the boat, both ahead and astern, so these boats steer much better astern than an inboard with a rudder. But with no thrust (in neutral) there is very little steering at all.

The pivot point

A boat turns about a pivot point. Going ahead, on a typical displacement motor cruiser it lies about one third of the length back from the bow. Going astern it moves aft, to about one quarter of the length from the stern. This means:

• Going ahead, the stern swings out further than the bow when you turn. Leaving a berth by steering away from the wall will swing the stern into it.
• Going astern, the bow swings out more.

Always check your stern as you turn away from a wall or other boat.

Prop walk

What it is

A propeller does not just push water aft. Because the blades at the bottom of their arc are in denser water, and because of the angle of the shaft, it also pushes the stern sideways. This is called prop walk (or paddle-wheel effect). It is strongest at low speed and going astern, when there is little flow over the rudder to counter it.

A right-handed propeller turns clockwise when viewed from astern going ahead. Most single-screw inboard boats have one.

• Going ahead, a right-handed prop pushes the stern slightly to starboard (the bow goes to port). It is weak and the rudder easily overcomes it.
• Going astern, a right-handed prop walks the stern to port. This is much more noticeable.

A left-handed propeller does the opposite: going astern, it walks the stern to starboard.

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How to find out which way your boat walks

Tied up in a berth, put the engine in astern at low power and watch the prop wash. If the wash comes out on the starboard side, the stern is pushed to port: right-handed. Or, in open water, stop, then go astern and see which way the stern goes.

Using prop walk

• Berthing: with a right-handed prop, berth port side to if you can. As you come in at a shallow angle and give a burst astern to stop, the stern walks to port, into the wall, and the boat lies neatly alongside.
• Starboard side to: going astern to stop will pull the stern away from the wall. Approach at a shallower angle, and expect to use a spring or a burst ahead with helm to bring the stern in.
• Turning in a confined space: turn to starboard (clockwise). Each burst astern walks the stern to port, which helps the turn.
• Reversing in a straight line is hard; prop walk will swing the stern. Get some speed up first so the rudder works, and expect to correct.

Single and twin screws

Single screw

Most small and medium charter boats on canals have a single engine with a rudder. They need careful use of short bursts of power, prop walk and lines.

Twin screws

Twin-engine cruisers have two propellers, one each side, usually outward turning: the starboard prop is right-handed and the port prop left-handed, so their prop walk cancels when both run together.

With twin screws, you can steer with the engines alone:

• Both ahead: the boat goes straight ahead.
• Port ahead, starboard astern: the boat turns to starboard in its own length.
• Starboard ahead, port astern: turns to port in its own length.
• One engine ahead alone: the boat turns away from that side, for example port engine ahead turns the boat to starboard.

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At low speed in close quarters, many skippers leave the wheel amidships and steer only with the gear levers. Use idle speed in gear for most manoeuvres; add power gently and briefly.

Bow thrusters

Many charter cruisers have a bow thruster, a small propeller in a tunnel through the bow that pushes it sideways. Use it in short bursts; most electric thrusters overheat if run continuously for more than about a minute. They lose power quickly as the boat gains speed, and in strong wind they may not be enough to hold the bow. Treat a thruster as a help, not a replacement for good boat handling.

Wind

A motor cruiser has a lot of windage, especially at the bow and on the flybridge, and a shallow forefoot with little grip on the water. As soon as the boat slows down, the wind takes the bow:

• At low speed, the bow blows off downwind first, and the boat tends to lie beam-on or stern to the wind.
• Going astern, the stern tends to go into the wind (the bow blows away), so reversing into the wind is often easier than reversing downwind.
• Strong gusts can push the boat sideways faster than you expect. Keep enough speed for steerage, and plan escape routes.

Rule of thumb

Before any manoeuvre, ask: where is the wind from, and where will it push my bow? Plan the approach so the wind helps, not hinders.

Turning in a confined space

Single screw: the three-point (or multi-point) turn

To turn a single-screw boat with a right-handed prop round in a narrow channel:

1. Slow down, and start near the left side of the channel, so you have room to turn to starboard.
2. Wheel hard to starboard. Give a short, firm burst ahead. The prop wash over the rudder kicks the stern to port and the bow to starboard, with little forward movement.
3. Neutral. Leave the wheel hard over (on most boats it makes little difference astern, and it is ready for the next burst ahead).
4. Short burst astern to stop forward movement. Prop walk pulls the stern to port, helping the turn.
5. Repeat: burst ahead with full starboard helm, then burst astern, until the boat has turned.

The key is short, firm bursts of power, rather than long gentle ones that build speed. In wind, start the turn so the bow turns through the wind, rather than against it, if you can.

Twin screws: turning in own length

1. Wheel amidships.
2. One engine ahead, the other astern, at the same low power (for a turn to starboard: port ahead, starboard astern).
3. The boat turns on the spot. Adjust the power to stop it drifting ahead or astern.
4. Return both engines to neutral when pointing the right way.

Coming alongside

Preparation

• Fenders out at the right height on the berthing side.
• Bow and stern lines and a midships spring ready, cleated on board, led outside everything and coiled, with crew briefed on which to take ashore first.
• Approach plan agreed: angle, speed, and an escape route if it goes wrong.
• Nobody jumps ashore. Crew step off when the boat is alongside, from the widest point near midships.

Approach in still conditions (right-handed prop, port side to)

1. Approach at about 20 to 30 degrees to the berth at dead slow.
2. Aim for the point where you want the bow to end up.
3. About a boat length off, put the engine in neutral and let the boat glide.
4. As the bow nears the berth, turn slightly to starboard to bring the boat parallel, and give a short burst astern to stop. Prop walk pulls the stern into the wall.
5. Crew step off with the midships line or spring and secure it; then bow and stern lines.

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Wind blowing onto the berth

Approach parallel to the berth and a little way off. Stop, and let the wind blow the boat gently sideways onto the berth. Make sure fenders are out and keep the approach slow, since you will hit harder than you expect.

Wind blowing off the berth

Approach at a steeper angle (up to 45 degrees), with more speed, and get a bow line or midships line ashore quickly. Then motor gently ahead against a midships spring with the wheel turned away from the berth, which holds the boat alongside while the crew secure the other lines.

Into the tide or current

On a river, always berth facing into the current. The current gives you control at very low speed over the ground, and you can stop by matching the current. Downstream approaches are fast, hard to stop and dangerous.

Leaving a berth

Springing off

When the wind or current is holding the boat against the berth:

• Stern out: rig a spring from the bow to the berth astern (a bow spring). Fender the bow well. Go gently ahead with the wheel turned towards the berth. The bow is held, and the stern swings out. When it is well clear, slip the spring and go astern clear, then ahead.
• Bow out: rig a stern spring forward to the berth. Fender the stern. Go gently astern. The stern is held and the bow swings out. Slip and go ahead.

Choose the spring that suits your prop walk and the wind.

Leaving in calm conditions

Push the bow off by hand or with a boathook, motor ahead slowly, and watch the stern as it swings towards the berth because of the pivot point.

Man overboard under power

Immediate actions

1. Shout "man overboard" and say which side.
2. Throw a lifebuoy or danbuoy towards the casualty.
3. Appoint a pointer to point at the casualty continuously.
4. Press the MOB button on the GPS or chartplotter.
5. Turn the stern away from the casualty. On a boat with an exposed propeller (outboard, outdrive), stop the propeller near the casualty if you can do so safely; the propeller is the biggest danger to them.
6. Send a DSC alert and MAYDAY if the casualty is not immediately recovered or is injured.

Returning to the casualty

• Turn the boat round with a tight turn, keeping the casualty in sight.
• Approach into the wind (or into the current on a river), so the wind slows the boat and you have control.
• Approach slowly, aiming to bring the casualty alongside near the cockpit or the lowest point of the boat, forward of the propeller.
• At the last moment, go into neutral, so the propeller is not turning near the casualty. Stop the engine on outboard boats when they are close alongside.
• In a high-sided cruiser, the bow will blow downwind as you slow. Some skippers prefer to approach with the casualty on the windward side, stopping a little upwind, so the boat drifts down onto them. Practise both in your boat.

Getting them aboard

Use the bathing ladder on the stern only with the engine stopped. Otherwise use a lifting strop, or a halyard or davit, or a parbuckle with a net or sail. Treat for cold shock and hypothermia.

Worked Example: berthing a single-screw cruiser in a crosswind

You are skippering a 12 m single-screw cruiser with a right-handed prop. You must berth on a riverside quay. The current flows downstream at 2 km/h, and a 12-knot wind blows from the quay out across the river (an offshore wind).

1. Plan. Turn and approach upstream, into the current. The quay is on your port side heading upstream: port side to, ideal for prop walk.
2. Brief crew. Fenders out on port. Midships line to go first, then bow, then stern. Nobody jumps.
3. Approach. Because the wind is off the berth, approach at about 40 degrees, a little faster than usual, aiming at the point where the midships cleat will meet the bollard.
4. Stopping. One boat length off, turn to starboard to bring the boat parallel, and give a burst astern. Prop walk pulls the stern into the quay. The current also slows you.
5. Securing. The crew steps off with the midships line and takes a turn on a bollard. You go gently ahead with the wheel turned to starboard (away from the quay); the boat is held against the quay by the midships spring while the bow and stern lines go out.
6. Check. Fenders at the right height, lines adjusted, engine in neutral, then stop.

Common Mistakes

• Not checking cooling water after starting. Always check the exhaust.
• Not wearing the kill cord, or attaching it to something other than the helmsman.
• Long bursts of power in close quarters. Short, firm bursts turn the boat without building speed.
• Forgetting the pivot point: turning away from a wall swings the stern into it.
• Ignoring wind on the bow. At low speed it blows off fast.
• Approaching a berth downstream on a river. Always approach into the current.
• Jumping ashore, or fending off with hands or feet.
• Propeller turning near a man overboard. Neutral or stop before they come alongside.
• Running a bow thruster continuously until it overheats and cuts out.

Summary

• Check the engine (WOBBLE), check cooling water at start-up, and wear the kill cord.
• Going ahead, steering is good with short bursts of power. Going astern, steering is poor until you have speed.
• A right-handed prop walks the stern to port going astern. Berth port side to and turn to starboard where you can.
• Outward-turning twin screws can turn the boat in its own length: one ahead, one astern.
• The pivot point is about one third aft of the bow going ahead, so the stern swings wide.
• Wind blows the bow off at low speed; plan every approach around it.
• On rivers, berth and recover MOBs facing into the current.
• MOB: alarm, buoy, pointer, MOB button, return into the wind, neutral near the casualty, engine off before using a stern ladder.

Check Your Understanding

1. What does WOBBLE stand for?

Answer: Water, Oil, Belts, Bilges, Leaks, Electrics.

1. You start the engine and no water comes from the exhaust. What do you do?

Answer: Stop the engine at once, then check the raw-water seacock is open, the strainer is clear and the impeller is intact.

1. Which way does a right-handed propeller walk the stern going astern?

Answer: To port.

1. With a right-handed prop, which side is it easier to berth, and why?

Answer: Port side to, because the burst astern to stop walks the stern to port, into the berth.

1. Where is the pivot point on a motor cruiser going ahead, and what does this mean when leaving a berth?

Answer: About one third of the length from the bow. The stern swings out more than the bow, so turning away from a wall can swing the stern into it.

1. How do you turn a twin-screw boat to port in its own length?

Answer: Wheel amidships, starboard engine ahead and port engine astern at equal low power.

1. Why should you wear a kill cord?

Answer: If the helmsman falls overboard or is thrown from the helm, the engine stops, so the boat cannot run away or run down the casualty.

1. When recovering a man overboard under power, why put the engine into neutral before the casualty is alongside?

Answer: A turning propeller can cause severe injury. In neutral it stops turning; on outboard boats stop the engine altogether.