Wednesday 18 January 2012

On Manoeuvres (2)

This is one of an occasional series of postings about manoeuvring a narrow-boat on the canals and rivers. There may be other ways to achieve the same result. However, the method I employ has been devised or adapted by me using trial and error. (Trial and Error are two of my regular boating companions) Our boat is a semi-traditional in style and just over 50 feet long. Rosie has a keel depth of twenty five inches and weighs in at a tad over eighteen tons. The techniques described are intended to help new comers to boating and the forgetful like me! However, if you have crew available they can still assist when things get difficult by keeping quiet and not offering their advice.

Steering your boat in a straight line.

The mechanics of steering are very simple. The propeller on the boat is used to push the boat forward or pull the boat backwards through the water. The tiller sits in the water directly behind the propeller. Water from the propeller that is pushing the boat forward passes on each side of the tiller. Moving the tiller to one side will deflect the water and the deflected water will push the stern of the boat sideways. An analogy is that the boat is like a vehicle that has steering through the rear wheels only.

When steering, the boat turns or pivots round a central point. The point is midway along the centre line of the boat. Take a long narrow piece of paper and fasten it to a board with a drawing pin in the centre. If you move the bottom of the paper to the left, the top will move to the right and vice versa. The boat behaves in the same way when moving forward. If we want the front of the boat to move to the right, we have to deflect the rear of the boat to the left using the water deflected by the tiller. Its the same if we want the front of the boat to move to the left. We have to deflect the rear of the boat to the right using the water deflected by the tiller.

The tiller is used to steer the boat through the water. However, other factors such as movement of the water and the direction of the wind will also create some directional changes.  You will need to make frequent small corrections to the boat tiller to keep the boat steering in a straight line. If you stand at the rear of the boat next to the tiller and look along the length of the boat you should be able to “aim” the boat along the centre of the canal by sighting on trees and other objects in the distance.

When you move the tiller there will be a short - time delay - before the boat responds. Most people steering for the first time tend move the tiller to far at first. They are over correcting because of the short delay in the boat responding. This causes the boat to pass through the sighting line. This then requires the tiller to be moved in the opposite direction. Just to correct the boat back onto the sighting line. This over compensation will cause the boat to zig-zag along the canal. Just make small changes on the tiller and learn to wait for the boat to catch up.

Tip:1 Try and stand to in front of the tiller, as much as possible. If the tiller catches on an under water object the tiller can be wrenched to one side or the other and you could be propelled into the water.

Tip:2 When reversing the boat the tiller is leading and is much more likely to become snagged or to strike an object.

Tip:3 Boats can be quickly propelled backwards into a lock gate by the inrush of water into a lock. Whenever you are steering the boat in a lock, always stand forward of the tiller.

Here is the trick to steering in a straight line:

Only make small (think tiny) but often frequent adjustments to the tiller, as soon as the boat starts to drift off the sighting line. Then wait for the boat to start to respond and then move the tiller back to the centre just before the front of the boat comes into alignment with the sighting line again. The boat will slowly ease back towards the sighting line once again. You will get it back on course hopefully without passing through the steering line and needing any further corrections of the tiller. If you want to know how well you are doing, just occasionally glance behind you at the line of spindrift or smoothed water you will leave behind in your wake.

The faster the speed of the engine the shorter the delay before the boat responds to the tiller. The slower the speed of the engine the longer the time it will take for the boat to respond. If the steering becomes difficult and the tiller is wobbling and shaking much more than normal you may have something wrapped around the propeller or tiller. You may need to take steps to clear the blockage. First flick the propeller into reverse for two or three seconds at low power. Then go into forward again at low power. Do this forward and reverse change a few times. If the problem persists you may need to go down the weed hatch to remove the debris.

Remember there is no hand or foot brake on a boat. To slow or stop forward movement you will have to put the engine into reverse. If you lose engine power to the boat, then the boat will continue to glide for some distance before it comes to a stop. If you need to stop quickly and the engine has failed. You can rub the boat along the canal edge. Remember that as the boat slows down the tiller will start to lose any control over the boat. Essentially you are adrift on a moving boat!

For anyone new at riding a bike there are so many things to remember. However, the only way to become proficient is through practise. After a while, you just become confident enough to just get on and ride the bike. All done automatically without having to think in detail about anything. It is exactly the same with steering a boat, after a while it becomes second nature. You will automatically make the correct adjustments to the tiller, without thinking.

Previous On Manoeuvres (1)


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