NSW
391 posts
Just putting this out there ,has anyone else found that the fin set up on a thruster sup , seems to me the that the outside fins run better with foils on them , without this there seems to be drag. which i dont find on my shortboard surfboards.
VIC
17570 posts
I've never seen a fin that's not foiled but I'm guessing that you mean flat on one side?..and how much they drag have could have something to do with how much they are toed in and how big they are.
DJ
NSW
391 posts
Sorry did not explain that very well. meaning double foiled- rounded on the front of the fin to the inside face of the fin , not flat on the inside of the fin with a sharp side on the front of the fin. there are 80/20 and 50/50 foils.
5399 posts
Maybe what you found out is just that side fins adds a lot of drag. Especially ones with flat sides. Try some with inside (concave) foils, 50/50 foil are a waste on side fins: it provides not enough grip for the induced drag IMHO (they are great as rear fins on quads if the box are close to center however).
This is true also on shortboards, but modern shortboards have no glide, so this drag is not noticeable, unlike SUPs and mals, eggs...
Just remove the side fins and go single, you will be astonished by the speed. Then put back the side fins when you are in the mood, are ok to trade in drag for better grip in turns.
On the other hand, your shaper may have put the side fins boxes not at the optimal angle for the board.
