Good day Nigel. Sorry for the late reply, but I'm not so often on this site. Well, "WaveDancer" has a 75 cm longer mast, which stands in relation to her also 75 cm longer hulls also a bit further to the bow than the original T30. The main sheet is larger than the original. She performed extremely well upwind. And tacked also well under all conditions. But sure you have to practice with your boat, to find how it feels and how to sail it. Yes hobbyhosing is a typical doubelender characteristic. You can install some side-finns at the rear end, I heard it would help a bit, although the cockpit is very central and the movement not felt so dramatic. Here a sailplan: WD-Sailplan.pdf

BTW: The mast is slightly "bellied", this gives a much better shape to the sleeved mainsheet.

Thanks so much for the information on the sail plan ,im sure this will help very much , also good to know the tiki sails well , when you say belly in the mast i am presuming the bulge of the belly faces forward to flatten the centre of the sail a bit . was this built into a wooden mast , or do you have an alluminium one , sorry for all the questions