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-   -   Converting Acid 74 to tri-fin (http://www.star-board-windsurfing.com/forum/showthread.php?t=7397)

davide 4th October 2009 05:12 AM

Converting Acid 74 to tri-fin
 
In high-wind (3.5-3.7) + steep and high frequency chop conditions I never been too happy with my Acid 74 (2007): it is just too fast and becomes hard to control. I wander if a home made conversion to 3 fins might make the board slower and more controllable ... using small sides a-la old-fashioned Real Wind Power surf?

Big negative of the operation is that I will never be able to sell the board ... alternative is to get a slightly smaller board .

Ola_H 4th October 2009 05:19 AM

I don't think it will help. The reason to do it would be if you both have the control problem you mention and at the same time have problems going upwind. If upwind is OK, a better solution woud simply be a smaller fin, I reckon. Try to get a hold of a Drake Natural 20. It's a small and very soft fin that softens up the ride quite a lot compared tot the original 22 and also compared to many other wave fins.

davide 4th October 2009 06:05 AM

Quote:

Originally Posted by Ola_H (Post 35979)
I don't think it will help. The reason to do it would be if you both have the control problem you mention and at the same time have problems going upwind. If upwind is OK, a better solution woud simply be a smaller fin, I reckon. Try to get a hold of a Drake Natural 20. It's a small and very soft fin that softens up the ride quite a lot compared tot the original 22 and also compared to many other wave fins.

Upwind is fine, no problem. I generally use a Wardog High Wind 22 for 4.2-5.3 and switch to the Drake 22 with the 3.7. The drake is much softer and helps, but you are right trying a Drake 20 might be a good idea, also considering that we see maybe 5-7 days of 3.7 each year ... (one of which today, that I am missing due to a stupid out of the blue muscle spasm in my back!!!!)

carvesalot 4th October 2009 10:32 AM

I converted a 1999 Mistral freestyle to a tri fin, this year, I used Probox surf boxes and fins, I tried both symetrical and asymetrical fins (these are flat on the inside) . While no way near as versesed as Ola in twins, and I know he has converted at least something with boxes from Witchcraft, who are probably the authority on tri fins. And since I have one, can somewhat attest to their prowlness.
I did the tri fin more on a engerineering concept, to see if I "could" do it, yes I did, and to see if it worked any better than the same board with a single fin, well.... it did/does go upwind better, it does turn more abrupt, it I'm sure weights more, with the additional boxes .. but not alot. I received guidance from Witchcraft and Ola, regards, toe in and placement of the thrusters.Toe if I measured correct 1.9 on the side bite thrusters, the Probox system . after quite alot of research, fit the bill, strong light weight, can change either the cant, which is angle of the fins, just by replaceing the insert, and a short adjustment of fore//aft like a USBox. My fin arrangement is center 17cm Tarifa wave fin, and thrusters either 5 " sym or 4"asym, the more puzzling aspect is the 4"asym //flat on the inside were noticeably faster , I cut down the original center fin to 22.5cm but never tried it. I rode back to back with a single center 30cm MFC , and those I just described, which form my observations.
I learned quite a lot of rocker this, v that, and surf fin technology. I tied the boxes into the very bottom of the board to re- enforce the installation, but would go no larger than 5" on these. Real wind fins are a unique box. I would probably suggest mini-tuttle as a alternative to what I did, for the fin boxes like the large fins on the new *Board Quads , these fins are going to become very popular, they are like a directional kite board fin.

My project kept me busy over the winter here in Colorado, so I have no regrets, a low cost board, and like you said, probably won't get sold.
My 2 cents is the Acid is not a good donor for this, the EVO or Kombat would be better. This a 104L, and for sure quite a bit different than my newer boards. With the right board I think a very promising result might occur, I just think the width in the back needs to be wider. The Real Winds, Open Ocean boards are long and narrow, with very short side fins.

I would leave you with this...
you can't make a racehorse out of a pig........but you CAN make a fast pig !

your HSM compadre TO2D

Screamer 10th October 2009 05:08 AM

Davide
I know it's hard to resist this multifin frenzy right now. I have a simple solution that works extremely well on my acid74 with regard to high wind control....(I've survived gusts over 40 in mega chop)

Gain 15-20 kilos ;-)))

davide 10th October 2009 08:12 AM

Quote:

Originally Posted by Screamer (Post 36109)
Davide
I know it's hard to resist this multifin frenzy right now. I have a simple solution that works extremely well on my acid74 with regard to high wind control....(I've survived gusts over 40 in mega chop)

Gain 15-20 kilos ;-)))

Damn, I am going in the wrong direction: end of the season here in SF and I am down to my muscly 69Kg ... lost 2Kg!


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