The Steersman

 The Steersman is a ‘Jib Sheet to Tiller’ type Self Steering system designed for tiller steered yachts between 20ft and 30ft (6m to 9m), although it is hoped to expand this range in the future.

 The Steersman is a purely mechanical system which keeps the vessel on course relative to the wind direction. It operates in all sailing directions, and wind conditions.

 Unlike conventional self steering systems, the Steersman does not use a wind vane to sense the wind direction, but instead uses the changes in wind pressure in the foresail (jib) to sense and control the tiller movement, also unlike wind-vane steering all the parts of the mechanism are contained within the cockpit area. It is simple to use, and easy to install.

 How does it work?

Each jib sheet winch is mounted on a swinging platform – the winch platform, so that as tension in the jib sheet increases, the winch swings towards the front of the boat. To resist this movement, a spring mechanism made up of a length of chock cord fitted in a block and tackle arrangement pulls the winch platform towards the back of the boat, and the tension in the shock cord is adjusted to balance the tension in the jib sheet. The pivot point of the winch platform is at the in board end, and an arm (pivot arm) is fitted to the aft end of the winch platform to transmit any movement to the tiller via a removable pole, the tiller arm.

If the boat luffs up to wind, the pressure in the sails drops, the jib sheet goes slack, and the shock cord spring pulls the winch platform aft, which causes the tiller to steer the boat downwind and bring the boat back on course. Conversely, if the boat steers downwind, then the pressure in the sails increases, increasing the tension in the jib sheet which pulls the winch platform forward, and causing the tiller to steer the boat back up wind.

For different points of sailing, the tension in the jib sheet changes dramatically, high tension for close hauled, medium tension for reaching, and low tension for broad reach or running. The shock cord spring works with this large variation in the following way.

The shock cord spring is made up of a double block at the stern end, and a single block at the winch platform end, which is attached to it using a snap shackle. The ‘cord-start-end’, is also at the winch platform end and it too is attached to it by a snap shackle. The adjustment end of the spring is on top of the winch platform, and is adjusted using a jam cleat. This means that there are 4 shock cord lines which make up the spring. Attached to the stanchion adjacent to the winch platform is a keeper eye.

For close hauled sailing, the single block and the cord-start-end are attached to the winch platform. For narrow reach sailing, the ‘cord-start-end’ is moved to the keeper eye, so that only 3 lines make up the spring. For beam reach sailing, the single block is moved to the keeper eye, and the cord-start-end is moved back to the winch platform making two lines for the spring. Finally for broad reach sailing, both the ‘cord-start-end’, and the single block are attached to the keeper eye so that only one line acts as the spring. For lighter winds, this whole arrangement is abandoned, and a single lighter shock cord line is fitted in its place.

With the wind on the quarter, the tiller movement works in the opposite direction to up wind sailing. In these positions, the jib sheet/spinnaker sheet is led through a block attached to the stern quarter of the boat, and fed back up forward to the winch via a foot block causing the winch platform to swing towards the back of the boat as the load increases. To counteract this, the shock cord spring is fitted along the side deck, and fed round the guide in the foot block, then through the jam cleat.

There is a transition band somewhere down wind of beam reach sailing when either set up can be used.

For goosewing sailing, the rules revert back to normal

Under each winch platform is a locking mechanism so that when locked, the winch can be used for normal sailing. Also, with the winch platform locked, and the tiller arm fitted, the helm is locked in the for/aft position. This can be very useful as a temporary measure while setting sails and the shock cord spring, etc.

Benefits

·        Easy to use

·        Works in all wind conditions except light airs

·        Works in all sailing directions relative to the wind

·        No ugly framework attached to the stern of the vessel

·        Blends in easily with the cockpit design

·        Eco friendly

·        Ruggedly built; should last a lifetime

For more information, please contact:

Rob Chicken

Tel: 01488 684697

Fax: 01488 686425

	Sailing close hauled   Computer model showing the winch platform, pivot arm and tiller arm. The orange lines are the shock cord spring, and the blue line is the jib sheet. The tiller is seen at the top of the picture
	Sailing down wind This view shows the shock cord spring (orange) on the side deck, and the jib sheet (blue) passing round the upper foot block before passing round the self tailing winch
	Production model