After searching the archives, I still have a question related to fin spacing on a twin fin. I’m working on a 6’11 twin 15.5N 21.75W 15T. I was looking at placing the fins 8.5" from the tips of the swallow, 1.5 in from the rail and toeing them in 3/16, slight vee through the tail.
My question is: with this spacing the leading edges of the fins will be about 10.25 inches apart, which looks a little close to me. Is there a minimum amount of distance which should be left between the fins so the water flows unrestricted ? I seem to recall reading that if the fins are spaced too close the water "jams up " for lack of a better term. The board is for East Coast waves 2’-6’. Anybody have experience with building good twins that could tell me if this looks OK?
Hope you West Coast guys get some good swell this week!
I had over 9 twin fins with tails narrower than 15", and one that was right around 11".
So on all those, spacing was narrower than 10", but they worked fine. Some had NO toe-in, and worked fine.
Some had 7" fins, one of the 5’8"ers had 8" fins for bigger waves, and it worked fine.
Of course, as you get narrower in the tail, the need for a twin fin design lessens, taking away it’s greatest character…quick pivoty turns with short distance drive.