Shout out to Bill Thrailkill for advice and the original idea!
I finally got around to finishing off and riding the twingle fins for my 7’6" and it felt good. Easy to turn - noticeably easier than the straight single - and with heaps of drive off the bottom and coming out of cutbacks. I rode it in fat 4-5 foot rollers at my local longboard spot on a clean offshore day - about as good as it gets at this place - and I got plenty of waves, both lefts and rights, which allowed me to really put the setup through its paces.
I’m sold. That’s all. It’s great. All the hold of a single, with increased turnability and reduced drag. Everything it was supposed to do. Hooray.
Unfortunately I’m having a bit of trouble uploading photos at the moment, but as soon as I’ve worked that out I’ll post some pictures.
The fins themselves are 7.5" single foiled dolphins using a combination of 9mm marine ply, fibreglass & batik cotton. The tabs were offcuts from a larger panel, with the pre-foiled ply fixed on top with 5-minute epoxy. I reinforced the join using strips of glass rovings laid into grooves routed carefully into the thickest sections of flat side of the fins. I sanded these back to flat then glassed a sheet of cotton fabric over the whole side - both timber and glass. After this I glassed on an extra three layers of 4oz glass over both sides and sanded the whole thing back to 320.
The toggles that hold the fin in the box I got from a stainless steel pin pulled from one of the kids’ old scooters, but I had to buy the screw and plate new. They finally arrived last week and yesterday was the first time that I had a free day coinciding with the right swell/wind combination to try them out. Worth the wait!
It’s not letting me post images, either through links or direct upload from my computer. So I’ll post links to the images and you can check them out at your leisure.
Cheers Gdaddy, that board was a labour of love for sure. I’m trying to replicate it at the moment, but with straight stringers and a little more nose rocker so it can make steeper drops.
The recommended fins are glass, 3/8ths inch thick single foiled. One of the reasons is that a 3/8ths single foiled fin, has the same camber as a double foiled fin that is 3/4ths inches thick. Thicker fins have superior hydrodynamic performance. The fins must have a blunt rounded leading edge, not the sharp leading edge, so often seen in commercial offerings. Fin flats toward the rails. Actual experience, with the setup, will open your eyes and your mind.
Thank you, Bill! I guess I need to build my next board as a twingle, does the twingle setup fit to any board, which usually goes with a single fin? I’m thinking of a 7’4’’ egg style
