This is a rudder that will not allow the boat to keep racing, but is very cheap and easy to build, and also light weight and easy to stow. It has been tested on a Merit 25 and on a J-24 with the main rudder removed with very good results. Larger versions have been built for a Cal-40, a Santa Cruz 52 and a Beneteau 57.

The most successful big-boat test was on the Santa Cruz 52, where it allowed good control, including tacks and jibes in moderate wind with the main rudder either locked or free. The Cal-40 was not tested (Unlike Pac Cup, Transpac rules do not require a live test). The Beneteau 57 version passed the inspection test but probably should have been built with more sail area.

The bottom "gudgeon" is a pair of pad eyes low on the transom. Gudgeon lines are lashed to the spar just above the rudder sail and lead through these eyes and then up to cleats on deck to hold the spar close against the transom.

The top gudgeon is at the lifeline level. In this case, a short spar is clamped between the two corner pulpits with an eye on centerline for the top lashing to the rudder stock/mast.

Note that it is necessary to control twist. This is done with a "vang" between the top end of the stock/mast and the aft end of the tiller/boom. To keep the gooseneck lashing from slipping aft under thrust from the vang and sail, an inhaul is rigged from the gooseneck lashing to the forward end of the tiller/boom.

For the Santa Cruz 52 installation, the sail was professionally built to order. Spars are from scraps of broken carbon spinnaker poles from boats of similar size. The as-build dimensions are smaller than designed to match the size of the spar fragments available.

The Cal-40 and Beneteau 57 versions are designed to use the primary spinnaker poles. Similar diameter spars were used for testing, but not brought along for the race.

As rule of thumb, a big boat's own spinnaker pole is probably only about half as strong as necessary for this design. However, loads can be moderated by carefully limiting the length of the tiller so that a human driver will not be able to push hard enough to overload the spars.

Spars prepared in advance for this type of emergency steering should be wrapped with additional fiber and resin to increase strength in way of areas of high bending load.

Another possible problem is flutter caused by periodic vortex shedding around the circular spars. This was has not been observed to any significant extent in trials to date, but a possible fix would be a larger luff pocket in the sail with a foam insert to fair in the trailing edge of the spar.

"Underwater luffing" has not been observed, but it seems desirable to keep the rudder sail very flat and to use battens to suppress any tendency to flutter.