fin position - twin fins MR template on fish



I’d need your advice on how to position MR style twin fins on a pretty classic fish that I have built. the board’s dimensions are 6’0/21,5"/2,75" with a deep buttcrack. Flat with Vee in the back


My fins are plywood with a 130mm base and 140mm depth. I have looked into the archive and found tons of info on keel positioning but only little for the fins I have built for that kind of board. 


How much toe? cant? How far forward?


Looking forward to your thoughts on that…



You mean you have shaped a classic fish shape but want to use MR template fins? Are you going to add a trailer? Reason I ask is you will need it! The MR templates are not big enough for the tail width and long rail line of a classic fish. Two things will happen, one, you’ll have poor drive, and two, you’ll be sliding out like crazy. The keel fins provide much more hold and drive because of the long fin base. If you do choose to set MR fins, add a trailer fin, like with the MR TFX set that FCS makes. As for positioning, I can get some measurements for you if you choose to pursue it. Let me know, and good luck!

Yes, i have shaped a classic fish and want to use MR template fins. I once rode a very similar board (shaped by Juanito, Bretagne, France), same dims (see above), parallel outline and it was a fantastic ride. it turned on a Eurocent, was drivey, perfect for small waves. Actually riding that board for a day made me want to start shaping my own boards.


This will be board number ten and it’s the first with those kind of fins. I think I will give it a try and if it is not drivey enough or slides out i will add a trailer as you suggest, salted. thank you very much for your input. as opposed to keels i assume I should position the fins further forward? 8,5" from tail? 

convert those fin dimension to inches. Were mostly Americans.

measure and report tail width, tail rocker…at several points, …inches.

Those are the determining factors.


MR fins on a trad. fish?, sounds like your in over your head.


I’ll let someone else take over.



you’re right, here’s more data. Thank you for your comments.


Base: 5.1" 

Depth: 5.6"



Tail width is 16"

Tailrocker: 1,75"

Noserocker: 3"

I'll buck the trend here and say that you're OK to put more modern twins on a fish. Depending on the waves you're going to ride, 8.5'' - 9.5'' up is what I'd suggest.



Relieved to read your post, I hoped somebody would say that it works. The board is for small waves, I also left some volume in the tail to pick up wave energy. I hope that doesn’t conflict with my fin choice. 





Hi Kalmeer,

Here is the fin info from an actual MR twin fin… the board is 5’ 10" by the way

rear of fin is 10 1/4" from tips of the tail

5 1/4" fin base

5 1/4" tall fin

rear fin point is set 1 3/4" inches in from the rail, with a 1/4" toe and 5 degree cant.

Good luck, looking forward to hearing your results!

…and things to bear in mind… the tail of a MR twin is narrower than a fish, has lots of vee, and is pretty foiled out (not to mention the fluted wings), so there is a pretty big difference in volume overall that you might want to compensate for. If you go with approximately the same size fin and positioning as an MR twin, then I would almost guarantee that you’ll need a trailer fin, but you can always add it after some testing if you find that it needs it.

Hi Karl,


All pretty accurate info on here and info worth considering.

I just measured my MR 6'2" and fins measurements were exactly the same as for the 5'11" that Salted quotes above

The suggestions on here re: performance are also pretty much spot on in my opinion... but that said, there is nothing wrong with experimentation, so I'd suggest installing using a fin system like Probox and work out how to position the fin system so that you can get the right fin pos for MR Twins and then be able to switch in some keels also in the right fin pos.  The reason why I recommend Probox is that it will allow you to move the fins forward and back so with a bit of thinking, you should be able to position the fin system so that it suits both MR twins and Keels. (Trailing edge for Keels should be 1 1/2" from rail and further back than MR Twins but a keel with a tab in the right place should allow you to get the trailing edge further back and closer to the rail than the MR twins)  I've never tried to setup a board to suit both but I'm sure that you'd beable to work it through.

From the board dims you describe above, I'm guessing if you setup the board to be able to ride both MR twins and keels you'll ride it as a twinny for a few surfs, decide it sucks, swap in the keels and never look back.

Just my thoughts.


Forgot to add:

Recommendation for MR TFX style fins with a trailer may help but from your description above of having a “deep buttcrack” it doesn’t sound like you’ll have foam in the right place for a trailer fin.

hi mike, i set mine @ 9 1/2 but less angle and cant and didn’t needed a trailer fin. the trailer goes only in with a compromised thruster position. i would think the twin is also good for bigger boards maybe even guns.




hey uzzi

check this site out:

there you will see guns with twin fins for rasta, by aipa