There are many gears available now, using one of the basic principles. Here are the details of a simple gear which I devised and made for Stelda’. It has proved extremely effective, and has the special advantage that no major alterations to the boat involved apart from sawing a small arc off the trailing edge of the rudder.

The gear is basically very simple, consisting of a stout beam clamped onto the bumpkin and braced to the transom, upon which is mounted a tripod for the upper vane-shaft bearing. The wind vane shaft, when shipped, is pinned to a gear wheel running on a standard thrust bearing. Above this gear-wheel is a rotating with a gravity latch operated by a piece of cord, the arm being connected to the tab-tiller by cord running round two pulleys.

The beam, of 3 in. by 1.1/2 in. ash is of sufficient length enable the vane to clear the backstay. It supports a tripod of half-inch stainless steel tubes with a tufnol block at the apex drilled to give a free fit to the vane shaft. The vane steering-arm is of 3/4in. marine ply sandwiched between two 1/4 in. tufnol plates with a latch of 1/4 in. stainless steel filed to fit into the gear-wheel teeth The lines from this arm are of pre-stretched terylene ruining round two outboard motor steering pulleys mounted on wood blocks. The tab tiller is of 1/8 in. stainless plate clamped onto a ¾ rod carrying the rudder tab of 3/4 in. marine ply 5 in. wide The tab shaft runs in three tufnol bearings bolted to the rudder and stock.

The wind-vane itself is of 1/4 in. marine ply clamped onto the shaft, the latter being 1 in. diameter tube. The vane is counter balanced by a folding arm on the end of which is a lead weight.

Two factors are of extreme importance — the end of the tab tiller must be exactly over the centre-line of the rudder pintles the relationship of the tab and main rudder areas is critical.

For safety reasons the vane should be clamped, not bolted, to its shaft so that in the event of a sudden and strong change of wind direction it can move round the shaft instead of carrying something away. It will be seen from the drawings that the whole vane and shaft ly may be unshipped at will simply by lifting it out of its top bearing.

I have found that little finesse is required to use the gear on or off wind. Reaching is a little more difficult, and the solution seems to be to trim sail carefully, let the boat bear off the desired by a point or so, lock in the vane and bring her up onto course again. This induces some wind pressure to counteract the slight weather-helm, which most boats carry when reaching.