It seems like channels are not uncommon on twin fins, must be something to it. I haven’t ridden a twin fin on a regular basis for ages, not really since my Lis type fish I had custom shaped in 1976. I loved that board! I have a hollow wood fish that’s like 6-10 or something, might be 6-8, but its heavy and just a room decoration. Although the few times I’ve taken it out, it rides smooth as butter. So I’m pretty stoked to start riding a twin again. Now that I’m older and riding mostly longer (8’ plus) boards, I would like to find out how to design a good twin fin longboard. I know this thread hasn’t generated a lot of interest, but the comments and pics that have showed up are all pretty cool, keeping me motivated to try. BTW, here’s a twin fin that ACE posted awhile back, an old board he shaped back in the day, that still looks pretty contemporary.
Such an awesome video here. Sorry - no specifics on fin placement, toe, or cant. I know for certain that even if I got it ‘just right’ I’d never be able to surf like he does…
And a pic of one of his shortboard twin set-ups… looks like slight toe/cant. I’m not sure of specific numbers:
And there are these as well
Nice video - Someday, maybe I’ll have a chance to play around with channels/twin combo. I’m sure that it adds directional stability to the setup
The variables are countless!
Thanks for the replies
Merry Christmas - Happy Holiday - Happy New Year
Thanks John great video of great surfing on a mid size twin fin , so smooooth .
Huck, thank you for posting the Ace board. I like it.
Looks very similar to what Ryan Lovelace does with his FM. Fins a bit bigger than twin fins (about 6") and a bit further away from the rail.
Recently I ride my twins and my duo inspired boards a lot. I like both. I think the setup like on the Ace board and the Lovelace FM could give me best of both worlds. I think I’ll try that on my next midlength.
I planned on spending some time polishing the bottom and putting some plugs in to try this out with a 5-1/2" fin on the toe side and a pair of fins on the heel side.
That was one of my original reasons for the twin fin query. It seemed like the placement of a large fin on the toe side, as is fairly typical on asyms, would share a lot of the same principles as twin.
I drove past the beach on the way to my shop - It looked fun - Glassy, offshore…
Decided that I’d rather be in the water, so I sanded the bottom to 180 grit and put a single fin in the box.
It ended up that the conditions changed and it’s not small and fun any more - Well, my board’s waxed and I’ll polish it some other time
Low tide is in 4-1/2 hr
When I try a multi cluster on that, I’ll post
Thanks for the feedback - Greatly appreciated!
I had my 6’10 channelbottom twin put at supertubos today. The size has been perfect for a landlocked guy and holiday warrior like I am. I don’t often surf waves like this (quite steep and fast for my standards). The board did everything I hoped it would do and I had a lot of fun.
I don’t really have nice pictures, just a couple of mobile phone shots that give an impression of the shape ( picture 2 and 4) and size (picture 3).
I used a self foiled fin set that is kind of a cloned fcs power twin. It was fast and had very good hold. Never slipped, though I was standing with a very forward stance right from the takeoff, trying to keep up with the speed of the waves/barrels.
I think this guy was sitting next to me. (much better surfer than me) It’s probably me sitting outside on the left. This is a better shot of the wave than my mobile phone pictures.
I was surprised, how good and predictable the twin felt. (But I don’t have alot of experience in waves like this.)
Awesome that you got good waves, & that the twinnie worked so well. I’m getting stoked on trying mine soon!
Hey man, Happy Hodad just emailed me the rules for Twin Fins. About ten pages worth. Gotta read thru them. i’ll get layback to ya. McDingy
Seriously? Should be interesting to see. Keep us informed
I’ve been analyzing the pics of the Pearson twinnie longboards and from what I can tell from the pics and from what other guys post, I may have lucked out and got it right.
My first post shows a pic of what didn’t work
I kept the distance of the trailing edge the same @ 9" from the tail and changed the toe in from 5/16" to 1/8" and moved it to 1" from the rail, as opposed to 1-1/4"
Also there are some channels that should provide directional stability.
This is for the toe side of my asym 8’0"
Waiting for the right day… Unbearable - It’s been about 18’ the past few days…
Thanks for posting, Guys
So searching the internet, there is a good bit of info on twin fins, but like here, its kinda all over the place, and hard to find specifics on placement, etc, especially when you get outside the standard fish or swallowtail shape on a shorter board and start talking midlength, longboard, squash tail, etc. But you get the feeling most people view them as an evolutionary blind alley, a dead end, cul-de-sac, whatever, on the road to the be-all do-all thruster.
But like most flotsam and jetsam tossed overboard in the rush to the Next Big Thing (thruster), some people are going back and taking a harder look, and finding value in the twin fin setup. Torren Martyn being just one of several. Still, the constant addition of channels seems to be saying the two fins alone are just not quite enough, they seek a little more lateral surface area to fight the tendency to slide or drift.
I love how guys will say build several boards with the fins in different places and take notes. I’m 64 years old, I’ve built like one board a year for the past 6 years, so using that approach, maybe I’ll have some progress by the time I’m 70 or so, haha!
I’m also thinking I will hedge my bet with a single fin box. The board should work as a single fin anyway, I feel pretty confident about that, if less so as a twin, since I have so little experience with twins.
We’ve got some things in common - 8’ Twinnie experimentals and shaping one board a year…
Those futures boxes are a commitment, once they’re in, it’s a major project to change them.
If you try something and it feels too loose, there’s a solution - Make it a twinzer. Unbelievable drive off the bottom and top and you can’t make it spin out.
I have to add - There is nothing that is simpler to do to a fin cluster than adding 2 little plugs and foiling a couple tiny fins - And it makes a VERY noticable difference
see pic
I’m starting out with a single fin too and keeping the box. There may be times when I’m thankful I have that option.
Good Luck!
Awesome conditions! Looks uncrowded! I’d love to find a day like that with no crowd
Thanks for the info and advice. Very helpful. I myself recently encountered a similar problem. I hope I succeed 
Gave it my best guess…
Not quite ready for the water, but almost.
[Quote]If you try something and it feels too loose, there’s a solution - Make it a twinzer. Unbelievable drive off the bottom and top and you can’t make it spin out.
I have to add - There is nothing that is simpler to do to a fin cluster than adding 2 little plugs and foiling a couple tiny fins - And it makes a VERY noticable difference
see pic
[/quote]
So are those little fins toed-in & canted? Flat on the in side? Any special distance / proximity to the twin fins?
Those little fins are a variation on twinzers. Someone else refers to them as Twonzers.
The placement follows the twinzer formula, but they’re smaller, yet they get the job done .
The most critical thing is that they are toed in parrallel or erring toward being more toed-out than the fin that they are paired with.
That is to be sure that the function is to feed water against the base of the bigger fin.
Other than that; The ones I make are foiled flat on the inside and they’re about an 1-1/2" high and maybe 3-1/2" long
The trailing edge overlaps the leading edge by 1/2" to 3/4" and is spaced about 3/4" to 1" away
Cant is the same as or greater than the trailing fin
I use FCS composite fins and just cut it down and foil it.
I’m discovering that there’s room for error and they still work as long as they are NOT toed in more that the trailing fin.
Altering the size and cant of the leading fin can be a method for adjusting drive or loosness
You can use a FCS side-bite fin just as they are, but then they have a tendency to trap your leash and if it gets caught in there and is pulled hard in the wrong direction, it breaks the fin.
There’s no question in my mind that you’ll notice a difference
Post results - Plz
I’ve experimented with the bonzer side idea with both 2+1 and twinzer sets and layouts, just like you’re doing in the first photo. For 2+1, I’ve even experienced two tiny little faux-bonzer sides made of plastic, about half the size and surface area of an average human ear (maybe half the area of a small True Ames runner from a Bonzer5 set) turning a 6-3 single from “meh” to “winner.,”
IMO you will eventually get better results with a more conventional canard in that set-up, but you will get great variation even with different canards.
I’m on a twinzer kick myself for months now. And have tried all kinds of fronts in the canard role, from randoms found in bargain bin boxes made of bendy, cheap plastic to the stock canards of all the majors (True Ames, Rainbow, FCS), as well as custom from Rich Sanders (aka Halcyon, here).
Rich says it’s best if the curve of the canards matches the curve of the twins. I think he meant by this the rear curve of the canard and the front of the twin.
My own experience is that if your twins aren’t fundamentally sound on their own (i.e. planing speed is satisfactory, but maybe hold/drive/release/pivot are not quite qhat you’re seeking), the board is not going to work as a twinzer either.
The miracle of the twinzer is that the canards add surface area and “overall fin” but they don’t slow the board’s paddling, or trim/planing (when working well, the board is significantly “faster” because drive is enhanced), and a good twinzer has almost a bonzer-ish feeling of unlimited potential acceleration, i.e. if the wave keeps giving you can keep driving the board faster and faster – much faster than even a quad set-up as far as the feeling of the board’s maximum possible speed down the line – and, at the same time, the board turns better, tighter/quicker more responsively – less like a twin, more like a quad, but with potentially tighter pivot than most quad sets in the same board.
And I haven’t yet made a twinzer that felt slower than the same board with quads. I came up with and am using a twinzer layout that bases the fronts off the back box position, with Probox, so that the twins are placed forward in the rear box to run the twinzer set, while the quad rears go in the back of the rear box. The canards will usually have the tab toward the front of the fin to allow them to sit closer to the fronts of the twins, with forward adjustability in the Probox front boxes, so that the same box is also functional for quad fronts. The only weird thing about this combo layout is that the rears are not the same distance from the rail apex that I’d use for a straight quad set, so I will end up using different quad rears than in my normal quad layout.
My noob rec would be to try some Rainbow or True Ames canards of similar surface area to the bonzer sides you have in the baord in the pic, with the canards set at least 2 degrees more cant than the rears, but not more than 4, and see what you experience differently, if anything. Then, if the board is slow but drive/hold are strong, start downsizing the twins, and then “recalibrating” the canards. I would also think about changing your plugs to Probox, because the position of the fins relative to each other does matter, at least in my experience, and with Probox you will be able to experiment with cant relationships without having to get (or make) new fins. Your forward plugs were interesting to me to see. I suspect they won’t really do much for any of the established types of layouts.
If you can get a good set-up going with stock fins, a master fin maker can then make you something even better if you have a good discussion about it.
I have Rich’s fins in almost every board of mine now – sometimes in combination with stock fins – because that’s my normal process: exhaust the stock fin options on hand (I probably have a more extensive stock fin library than most, maybe 40 or 50 different sets and singles in the library). Almost always, if I talk with Rich about my best results, with all the equipment on hand to look at, at the same time, he will end up making me something that improves on that previous best result.
Oh: one other thing to add: my first 20 boards or so, I reduced “default toe” from 1/4" (using the FaamEZ plastic “square” tool) to 3/16 or so, because I thought it would make the boards faster and not affect turning too much. When you make a broad study/survey of the mass produced boards in racks – e.g. CI and Lost, and regardless of size, up to the point when you get into boards released as 2+1, single, etc. – you will find that almost all of them have 1/4 toe. The only thing that has changed in recent years is that most fronts are set at 1 1/8 off the rail now for CI and Lost, whereas from a few years back through about 10 years back they were almost always at 1 1/4. Now at board #81, I’m back to 1/4" almost all of the time, and I would say the main reason is that I’m less likely to make a f***ed up board that is inherently slow. The first 20 or 30 boards, maybe 1/3 of the time the boards were not as inherently fast as I’d have liked, for me at my weight (they often worked better for someone of a different weight), and usually if the board was good it was good for conditions different from what the board was intended to match. Around board #50 the boards started consistently doing what I wanted and planned for them to do, and again I think that is why I’m no longer tempted and don’t feel the need to think about reducing toe in HPSB and HPSB hybrid boards. 1/4" toe, other things being equal, turns better than 3/16", imo, but of course there are a lot of other factors in play in that “other things being equal” premise.