no change in mast base position with a more foreward raked fin. I found the point as described before with -2cm as best position. With my more raked fin the F162 is more stable and has a fixed trim.
If your board nose is pushed down your fin has not enough twist stability and by this the tip turns to a more powerfull angle of attack if you rake it foreward. Thats why the Kashy is doubble twist stiff as a Debo. Thats the secret.