Twin Fins

toofast3 · Post by **toofast3** » Wed Oct 10, 2007 2:40 pm

Hey Matt.... I may not be the best one to suggest placement here`s my opinion any way and take it for what is worth...... As you know I ride twin fins 95% of the time. I like my fin placement way up. My 5-7 board, the fins are set at 16 1/2" from tip to the center between 2 FCS plugs. My 5-8 board, they are 16" to between the FCS plugs. You know my boards are looose. Both boards are set at about 1 1/2" in from the rails. The angle in which they are set at are basiclly connect the dots. Mark how far up you want them, how far in from the rail,and the last dot is the very tip on the nose. Another thing to remember is that I ride narrower boards then most and have the stingers. I`m sure the professinanl shapers here will give you their thoughts.... I`m like you, the backyard shaper...

red · Post by **red** » Wed Oct 10, 2007 3:02 pm

Hi mate,

I'm cutting a tiny wave comp board (knee high and under)
I'm setting this up for twin/tri but I haven't decided whether to put the twin fins in a different place to the tris.

I'm watching this with interest.

Red

skansand · Post by **skansand** » Wed Oct 10, 2007 5:46 pm

ya red, what brought on my interest in twin fins is my first board i ever shaped, and aussie tri roundpin that only saw thruster fins once , almost its whole life it had big twin fins and it worked great like that , just kind lacked drive and too loose in any serious overhead waves...

Mike Fernandez · Post by **Mike Fernandez** » Wed Oct 10, 2007 6:04 pm

Matt, go to Mutiny's house and check his Carl Hayward twin he has. That should answer alot of questions. We rode those things from 2ft slop, to 15ft Sunset, always worked. Carl's fin shape is to be studied also.

Headwax. · Post by **Headwax.** » Wed Oct 10, 2007 6:19 pm

Hello

It seems that twin fin position depends somewhat on how much "grip" you expect from the mini swallow.

etc

Mike Fernandez · Post by **Mike Fernandez** » Wed Oct 10, 2007 7:56 pm

I don't have any scientific facts to prove my point, but I will say the purpose of the twinny was to pump on the wave face down the line, generating massive speed, not necessarily only to get drive off of bottom or top turns. This was accomplished with the fins toed in, and layed over at an angle, the bases were somewhat shorter than the keel fin bases.
Very different from keel fins which are straight and upright with long bases.
With the board being flatter in the water while pumping on the face, IE not layed over so one fin is out of the water, the outside fin was causing a sort of jet water flow, or making pressure to generate forward momentum. I remember reading about how it works years ago.
You can feel it when you pump the boards down the line while being in the middle to higher up part of the face ahead of the pocket, not in it. You can't pump the board soley by making small turns though, you must ride it like a horse using your thighs to pump.
The tails were wide like fish, but a twin fin is NOT a fish. And a true twin fin doesn't have a small swallow tail.
Mark Richards pumped down the line, Shaun Tompson pumped inside the tube.
It was harder for the Cheyne Horan type single finners to keep up.

skansand · Post by **skansand** » Thu Oct 11, 2007 12:10 pm

mike , carl haywards boards are definetly something i wanna study more, the fact that Ler and Paul still ride his boards after many years of use speaks volumes of his crafmanship...

ive got access to a 5'5 quad/twinzer? with channel bottom that i can copy....but i have SO many prodjects at the moment with like 5 boards that need glassing and a spoon blank thats hull is slowly being refined...

i might add more boxes to experiment with but would would rather not, .. what would really be great is a 10" fin box with inserts to control tow in(like the Pro-box sytem)...

Did peter crawfords side boxes have controlable toe-in when the fin was moved back or forward in the box?

i might try these fins out in the aussie style ,(17" or so up....)

http://www.futuresfins.com/specialty-fi ... php?id=173

bit pricey at 83 us dollars but they look pretty snazzy and its for a good cause, and that kinda thing just sells me...

skansand · Post by **skansand** » Thu Oct 11, 2007 12:23 pm

http://www.futuresfins.com/specialty-fi ... .php?id=96

^looks like the hayward twins ive seen...

and a thread for toofast zeke,

http://swaylocks.com/forum/gforum.cgi?p ... ead#unread

..i know ive seen commercially made twin fins with like those^..just dont know where???

Mike Fernandez · Post by **Mike Fernandez** » Thu Oct 11, 2007 3:24 pm

I am not sure your considering this Matt, but if you look at Carl's fins you will notice not only are they toe'd in, but they lean over also. I don't think you can accomplish this with a box. I could be wrong, but I have never seen it. Looks like the modern quads we have only have toe'd in fins, not leaning over.
Talk to Tom if I am not explaining it easily. He can show you his board. It is key to twin fins though. Toe'd in is only half the equation.

skansand · Post by **skansand** » Thu Oct 11, 2007 3:50 pm

yes mike, the lean of the fin is called its "cant"....it helps tighten the ride i believe...ALL of my side fins(fcs and futures) have some degree of cant built into the fin....

probably not alot in your F2k cause of the large surface area of th f2k fins...

Beeline2.0 · Post by **Beeline2.0** » Thu Oct 11, 2007 3:56 pm

Mike Fernandez · Post by **Mike Fernandez** » Thu Oct 11, 2007 4:14 pm

Ok great. It's interesting how they build the tilt/cant into a fin with a box.

skansand · Post by **skansand** » Thu Oct 11, 2007 4:31 pm

all fin sytems are installed into a board with the box/plug surface totally flat with the blanks skin....

above the fins tabs the fin is set at its tilt...done differently varrying in materials...plastic is probably molded, fiberglass with a grinder and foam/carbon with sand paper before the carbons laid up....

verry interesting fin making is...but fins are hard to get right...with flex and clean foil needing to be precise.....

Mike Fernandez · Post by **Mike Fernandez** » Thu Oct 11, 2007 7:02 pm

Now if someone could explain the quad theory and the reason one set of fins are symetrical, and the other asymetrical, and what is the thought of one size in front or rear?

Headwax. · Post by **Headwax.** » Thu Oct 11, 2007 7:24 pm

gees I can ramble