Turning an old hybrid into a single fin

I have a 12 year old hybrid squashtail thruster (7’8" x 14.5" x 21.5" x 14.75" x 3") that I use infrequently. It originally had glass on fins, then I had removable fins put on so I could take the board on a long trip. Now I’m thinking of putting in a finbox and using it as a single fin. The outside fins could be removed, or little tiny “side bites’ could be inserted. I was thinking of a center fin like a 7.5” Rainbow TK Flex or a Trueames 7 or 8" Normflex. The question is - does the shape of a board (outline, rocker, rails, vee, etc.) that was built originally as a thruster convert that readily to a single fin? My eyes see the possibility, but if I hear from the wise souls on this site that stuff like that doesn’t always mix, then I’ll rethink it. Thanks.

I have a 12 year old hybrid squashtail thruster (7’8" x 14.5" x > 21.5" x 14.75" x 3") that I use infrequently. It originally > had glass on fins, then I had removable fins put on so I could take the > board on a long trip. Now I’m thinking of putting in a finbox and using it > as a single fin. The outside fins could be removed, or little tiny > “side bites’ could be inserted. I was thinking of a center fin like a > 7.5” Rainbow TK Flex or a Trueames 7 or 8" Normflex.>>> The question is - does the shape of a board (outline, rocker, rails, vee, > etc.) that was built originally as a thruster convert that readily to a > single fin? My eyes see the possibility, but if I hear from the wise souls > on this site that stuff like that doesn’t always mix, then I’ll rethink > it. Thanks. The TK flex is a good fin choice, 7.5 might be a bit small if the tail is square, what I would do is try out before you hit the road. You didn’t tell about the rails and rocker and the kind of surf you wanna surf, Bigger/hollow surf is a different balgame then small/slow surf. Peter Rijk.

The TK flex is a good fin choice, 7.5 might be a bit small if the tail is > square, what I would do is try out before you hit the road. You didn’t > tell about the rails and rocker and the kind of surf you wanna surf, > Bigger/hollow surf is a different balgame then small/slow surf. Peter > Rijk. Tail rocker (board on flat surface measuring from surface to underside of board) is 2.25 and nose is 5.25. Rails are relatively soft throughout but with a consistent tucked under edge from mid-board to tail. There’s noticable vee between the forward fins. Yes, I’m sure you’re right about fin size. That was a guesstimate. Eyeballing it at the fin emporium would likely be the final determiner. Wave size is waist to head high breaking on all kinds of bottoms ranging from shallow rock shelf to sand.

I have a 12 year old hybrid squashtail thruster (7’8" x 14.5" x > 21.5" x 14.75" x 3") that I use infrequently. It originally > had glass on fins, then I had removable fins put on so I could take the > board on a long trip. Now I’m thinking of putting in a finbox and using it > as a single fin. The outside fins could be removed, or little tiny > “side bites’ could be inserted. I was thinking of a center fin like a > 7.5” Rainbow TK Flex or a Trueames 7 or 8" Normflex.>>> The question is - does the shape of a board (outline, rocker, rails, vee, > etc.) that was built originally as a thruster convert that readily to a > single fin? My eyes see the possibility, but if I hear from the wise souls > on this site that stuff like that doesn’t always mix, then I’ll rethink > it. Thanks. Although it was shaped for a thruster set up, Id take the chance and have a fin box installed and ridden as a single or 2+1. It may turn out to be the best thing you did for that board. If not, you could still ride it as a thruster.

Put as long an adjustable box into it as you can. Moving a single fin up and back even a quarter of an inch will make a big difference in how it rides. By doing that, you can make almost any rocker/contour work fairly well.