RE: Go 155
Wow, great GPS speed results for the big GO 155!
Be careful with the 52 cm fin. If you "hook" the bottom at speed
with the vertical 52 cm fin you will get catapaulted pretty much for sure.
Might damage the fin or the fin box in the board also. So be very careful or sail somewhere in a deeper water channel (just to try the larger fin).
I looked at the Select anit weed 32.
A pretty nice fin, but it sits well behind the fin box and sticks out behind the board quite a ways and this could also be a factor here.
If you look at the weed fins (True Ames Shallow Water, Tangent Dynamics Reaper, Gorge Fin Co.Some weed) that are set well forward of the fin box, you can see that the designers have worked to keep the center of resistance of these "set forward" fins as close to where the center for resistance would be with the OEM stock vertical fins.
Sounds like the minor "wear" on your fin could be part of the problem, if you are having to reshape the leading edge and tip.
Hope this helps,