This was interesting since I've had about the same problems long ago, and ended up moving the seat back about 1 1/2 inches. This made the yak very neutral, and turned out to be about "ideal", and allows for a rudderless and skegless boat.

Carrying Greenland spares however revealed a new source of trim: moving the spare from the rear to the fore deck greatly changed the way the boat behaves in brisk winds. And vice versa.

I do have one question however: are you changing the exact location of the seat on a regular bases for fine trimming when conditions vary, or did you find an optimal all-round position for it?

risto

ps. if one were to keep moving the seat on a daily basis, on the water even, what might be the best way to fix it ?