Thanks Chris for taking the time to make the measurements and post them. It seems as if your hulls are canted the same way at the bow and the stern wheras mine are twisted. Or at least the rudders are canted the opposite way from the bows. It's all very slight, so who knows what the effect is!
Thanks also Greg for your thoughts. It just so happens that we had Aaron Worrell and Mick Butler passing through town last weekend. When I put the question to them, they said that in their experience the new version of the Tiger rudders (which I have) are sometimes set too far forward under the transom, and this may be the problem as it makes the steering more sensitive. So before I move them even further forward by removing the neoprene, I'm going to have another go at raking them back, this time using cable ties for packers.
We are racing this weekend so I'll experiment with it then and see if it makes any difference.
Hong Kong Hobie Club Fleet 179
Tiger "Rum Tum Tugger", Hobie 16