Steering a boat - the options
Posted: Tue Dec 22, 2009 1:15 am
One advantage of having an engine is the ability to power through any water in our way. The other advantage is being able to steer the boat to power through anything, ensuring it powers in the direction we want it to.
Over the years there have been many different ideas on how to direct finger tip force to move a rather stubborn rudder.
Tiller
The most basic method is to use a standard tiller. This composes of a stick, a hinge and a rudder. The move the stick to the port and the rudder moves to starboard due to the whole thing having a vertical pivot in the middle.
Main disadvantages are that the stick (tiller) usually takes up the whole of the back seat.
You also can't let them go, or the rudder and tiller will go wherever it wants to, and so will the boat.
One benefit is that they are really simple and difficult to go wrong. There is always something to go wrong of course.
Rope drive
Moving on from the tiller, the rope drive is quite a leap up in complexity terms.
The hand wheel end has a wide U shaped pulley, allowing for at least 3 turns of rope around it. The rope is conveyed from the wheel pulley to the rear via free-wheeling pulleys in appropriate locations. The rope is then attached to the quadrant.
The quadrant is a 1/4 pie shaped structure, the point being the pivot of the rudder. Its purpose is to allow the rope to pretend it is on a pulley on the rudder. If you was to use a simple arm, the tension of the rope would change as it moved. The picture below shows a quadrant with 1 rope attached.
The rope has been shown standing off from the quadrants surface for ease of viewing. A 2nd rope would be attached opposite.
Quite simply, as you move the wheel, the rope wrapped around the wheel's pulley is moved, which feeds to the stern and moves the quadrant accordingly.
The 1st major advantage is you can have the wheel anywhere on the boat, and the wheel can be as large or as small as you like.
One big disadvantage is the rope must run from the wheel to the rear and not rub on anything. Some people use copper pipe to allow the rope to run it.
The rope also stretches and shrinks. Wire rope can be used but steel wire rope will not like a tight pulley radius.
Chain drive
Just like the rope, only using chain and a sprocket on the hand wheel.
Problems are the chain can clunk as it passes round the other pulleys. Good points are the chain can't slip on the sprocket like the rope can slip on the pulley, unless you are doing something very wrong.
Chain and cable
This is the most commonly used one. You have a chain around the sprocket on the hand wheel, which then attaches to wire cable to run to the quadrant. The main advantages being you are using the better chain drive on the hand wheel and the more flexible and non-noisy cable to run to the rear.
Push/pull cable
There is a relatively cheap device out on the market now which is like a bicycle gear-change cable. It is a thick wire which runs inside a tube, flexible in parts to route it from the wheel to the stern, and solid at the ends so it can push as well as pull.
I have heard good things about them from other steamboaters.
Hydraulics
To some people, even the thought of the H word will be enough to send them cowering in the corner. However my dad uses a hydraulic system on Grayling, and with the exception of the odd incident resulting in hydraulic oil all over the place, it works very very well.
On our system you have a hand wheel driving the pump unit direct. This has 2 hydraulic pipes feeding off to the rear which feed into a hydraulic ram. The ram then moves the rudder.
The beauty of the system is the pipes, 8mm nylon I think, can be run anywhere (except maybe under the boiler). They are not effected by bends, distance or rust like the chain/cable drive systems.
The bad points - when you get it wrong it becomes very messy! I have also heard of 1 incident where the hydraulic ram's mounting bracket broke leaving the boat without steering.
However that aside, many people have commented on how nice the boat is to steer. It goes where you put it, it doesn't wander like most other systems, and there is practically no backlash.
I would highly recommend the hydraulic system.
Steam Servo Engine
If you are feeling ambitious, you could make yourself a servo system using steam.
Like the titanic, the hand wheel would operate (directly or indirectly) the valve timing on a steam engine or steam ram.
The wheel would tell the engine/ram to move to Starboard for instance, and the 2nd set of valves attached to the engine/ram would tell it to go the other way once the two vales were equal, thus forming a negative feedback system.
The engine/ram would then follow the 1st set of valves driven via the wheel.
The down side to this system is the massive complexity it had. The upside is there is no limit to the size of rudder which can be moved with almost no effort required from the operator.
Over the years there have been many different ideas on how to direct finger tip force to move a rather stubborn rudder.
Tiller
The most basic method is to use a standard tiller. This composes of a stick, a hinge and a rudder. The move the stick to the port and the rudder moves to starboard due to the whole thing having a vertical pivot in the middle.
Main disadvantages are that the stick (tiller) usually takes up the whole of the back seat.
You also can't let them go, or the rudder and tiller will go wherever it wants to, and so will the boat.
One benefit is that they are really simple and difficult to go wrong. There is always something to go wrong of course.
Rope drive
Moving on from the tiller, the rope drive is quite a leap up in complexity terms.
The hand wheel end has a wide U shaped pulley, allowing for at least 3 turns of rope around it. The rope is conveyed from the wheel pulley to the rear via free-wheeling pulleys in appropriate locations. The rope is then attached to the quadrant.
The quadrant is a 1/4 pie shaped structure, the point being the pivot of the rudder. Its purpose is to allow the rope to pretend it is on a pulley on the rudder. If you was to use a simple arm, the tension of the rope would change as it moved. The picture below shows a quadrant with 1 rope attached.
The rope has been shown standing off from the quadrants surface for ease of viewing. A 2nd rope would be attached opposite.
Quite simply, as you move the wheel, the rope wrapped around the wheel's pulley is moved, which feeds to the stern and moves the quadrant accordingly.
The 1st major advantage is you can have the wheel anywhere on the boat, and the wheel can be as large or as small as you like.
One big disadvantage is the rope must run from the wheel to the rear and not rub on anything. Some people use copper pipe to allow the rope to run it.
The rope also stretches and shrinks. Wire rope can be used but steel wire rope will not like a tight pulley radius.
Chain drive
Just like the rope, only using chain and a sprocket on the hand wheel.
Problems are the chain can clunk as it passes round the other pulleys. Good points are the chain can't slip on the sprocket like the rope can slip on the pulley, unless you are doing something very wrong.
Chain and cable
This is the most commonly used one. You have a chain around the sprocket on the hand wheel, which then attaches to wire cable to run to the quadrant. The main advantages being you are using the better chain drive on the hand wheel and the more flexible and non-noisy cable to run to the rear.
Push/pull cable
There is a relatively cheap device out on the market now which is like a bicycle gear-change cable. It is a thick wire which runs inside a tube, flexible in parts to route it from the wheel to the stern, and solid at the ends so it can push as well as pull.
I have heard good things about them from other steamboaters.
Hydraulics
To some people, even the thought of the H word will be enough to send them cowering in the corner. However my dad uses a hydraulic system on Grayling, and with the exception of the odd incident resulting in hydraulic oil all over the place, it works very very well.
On our system you have a hand wheel driving the pump unit direct. This has 2 hydraulic pipes feeding off to the rear which feed into a hydraulic ram. The ram then moves the rudder.
The beauty of the system is the pipes, 8mm nylon I think, can be run anywhere (except maybe under the boiler). They are not effected by bends, distance or rust like the chain/cable drive systems.
The bad points - when you get it wrong it becomes very messy! I have also heard of 1 incident where the hydraulic ram's mounting bracket broke leaving the boat without steering.
However that aside, many people have commented on how nice the boat is to steer. It goes where you put it, it doesn't wander like most other systems, and there is practically no backlash.
I would highly recommend the hydraulic system.
Steam Servo Engine
If you are feeling ambitious, you could make yourself a servo system using steam.
Like the titanic, the hand wheel would operate (directly or indirectly) the valve timing on a steam engine or steam ram.
The wheel would tell the engine/ram to move to Starboard for instance, and the 2nd set of valves attached to the engine/ram would tell it to go the other way once the two vales were equal, thus forming a negative feedback system.
The engine/ram would then follow the 1st set of valves driven via the wheel.
The down side to this system is the massive complexity it had. The upside is there is no limit to the size of rudder which can be moved with almost no effort required from the operator.