thanks for your reply roger,
the fin I use is 40cm deep, I think aprox 45 deg rake??, and the brand is "leading edge". Locally made in western australia in full carbon. highly reputable fins, but unsure as to how good the st126 seems to react to this fin. as I wrote. the board just doesn't want to plane that easily. I have to turn of the wind alot more to get going and when on the plane it doesn't feel like it is over fined.