View Full Version : Double fins?

30th November 2006, 03:52 PM
Some producers now seem to launch boards with two back fins for as they say ???improved upwind performance??. I don???t know if it works but it would suit me since the large Carve and Formula boards have long fins and when I sail in very shallow waters it sometimes takes time walking out to where I don???t have to be afraid to sail into sandbanks.

Are double fins something that you are looking into?

Best regards,

Niklas, Sweden.

1st December 2006, 12:41 AM
While boards with two fins does allow you to use smaller sized fins, it's important to keep in mind that a fin change will cost you twice as much. If you're buying the best fins, that will be a significant expenditure.

1st December 2006, 03:24 AM
Good point Steve... where I sail, that means getting two weed fins for the board right off the bat.

I know of some local sailors with the HiFly that comes with two fins. They seem to like the boards very much. And for shallower waters, the extra expense would be a good deal.

1st December 2006, 10:04 AM
Friend of mine has a HiFly Madd twin fin. He likes it; I don't.

I prefer my C131; just got an Aero 117, which I will have to test ride ASAP and can't comment vs twin fin at this point.

I concede that if you insist on using big sails, in really shallow water, it's probably a decent option. Otherwise, I'm skeptical.

1st December 2006, 03:09 PM
Where I sail during Summer there is a large extension of shallow water with mud on the bottom, rocks and sea urchins. I use slalom materials and I am disadvantaged compared to my buddies on frrestyle boards and fins; others on bigger boards or Formula materials are in worse troubles than me.
Last Summer I met a guy using a two fin board with great satisfaction and this made me think. In the end, with such a board you have to buy two fins at a time; but I am not quite sure about real double expenditure, as a longer single fin will more often hit the bottm and get damaged.
In the end, a twin fin board could be a good solution in shallow waters; the real doubt is about performance. Theorically, a single fin with high A/R should be better; but I am not sure this is thoroughly confirmed in practice.

1st December 2006, 05:25 PM
Performance issues aside, make sure that if you buy two fins that it is from a line where you can get an exact replacement a year on. If you break one fin it could mean you end up having to buy a new pair rather than just one.

1st December 2006, 10:06 PM
My thoughts are in the same line as .g.e.o. Where I sail I would prefer a board with two shorter fins and I would not hit the bottom as much as today. Is there a performance advantage or disadvantage?

It would be interesting to hear if Starboard shapers have an opinion and if they have tried a two fin configuration on larger freeride and possibly Formula boards? Could we see Starboard releasing a board with tow fins?

Best regards,


2nd December 2006, 06:48 AM
In the early 1980s there was a lot of experimentation with bottom shapes and what were called 'skegs'. One variant was the 'thruster' consisting of a main fin at the rear and a couple of smaller fins forward. The board turned on the front fins while the rear fin settled the board down. There were even some experiments with four fin boards which did wonders for turns but at the cost of speed especially on flat water. Today there are of course short boards that have short fins. However, as the WS has evolved over the years, may be it is good time for the twin fin to cycle through again; but probably not for those whose first preference is blasting.

2nd December 2006, 08:28 AM
NiklasR wrote:
My thoughts are in the same line as .g.e.o. Where I sail I would prefer a board with two shorter fins and I would not hit the bottom as much as today. Is there a performance advantage or disadvantage?


Based on observations sailing with my buddy...

In B&F sailing, if your option is a single shallow fin or a double shallow fin, in marginal to just powered up conditions, the twin fin is substantially faster (15-20%) and points higher.

When the wind picks up to where the single fin is powered to overpowered, the twin fin is much overpowered and one needs to fin down (reduce fin size). If you don't, the single fin board outperforms the double fin board, but not by 20%, more like 5%.

It's what you would expect, if the twin fin is equivalent to a single but larger fin.

My objections are in other areas; in shallow water performance, light to moderately powered, the twin fin outperforms.

2nd December 2006, 10:41 PM
Hi Niklas,

I have ridden the Madd 115 and Madd 165 and a lot of people in my area have the Madd 135. They are nice boards with some major advantages, and no serious disadvantages. I think that twins fins are really good for large freeride boards (115 + liters), especially for manoevers, control, and using a wide range of sail sizes. I wish more manufacturers would make them. The main differences in feel from single fin boards is that twin-fin boards don't rail up as much, and favor more inboard footstrap settings. They go upwind well and rarely spinout or tailwalk, and they adapt well to weed fins.

I don't think they're quite as fast as slalom boards or go upwind as well as formula boards, but they're pretty darn good for freeride boards, especially at going upwind.

4th December 2006, 05:36 PM
Thanks everybody for good answers. I am more than ever interested to try a board with two fins. Both for shallow water purposes and to try the performance and upwind characteristics.

Still no info or answer from the Starboard team...? It would be nice to stay with the same brand and it would be interesting to hear what they say. If it is as GEM says that in marginal to powered up conditions the tow fin configuration is faster and points higher it would be highly interesting to look into, or?



4th December 2006, 09:00 PM
Hi Niklas,
I would take what GEM suggests to the full explanation from my experience with twin fin designs (like the HiFly MADDs).
They are faster and better upwind (the twin fin design) ONLY if you are in water so shallow you cannot use the right size single fin, or a modern progressive rake weed fin.
My experience in Bonaire (a very shallow place where it's impossible to use fins much over 33 cm) was that for the larger Carves, and any of the wide boards (Starts, Gos, Rio's, Easy Riders), the "cut down to 33 cm" fins the rental operators must use for the super shallow conditions didn't work very well and the boards were hard to get on plane, and not real fast as there was not enough fin span to "ride the fin" on a single fin board.
I tried the HiFly Madds (mid size and large size) and they were better with the twin fins, in the shallow water areas, but the Carves and other wide boards were better upwind, faster, and earlier to plane when you could use the regular size single fin further down Lac Bay in the deepwater channel.
Also, I felt that the " fin toe in" on the MADDs might need to be adjusted as one of the fins always seemed to be slightly "spun out" (evidenced by the white turbulent "wake stream" behind the (usually) upwind fin when trying to sail the board "on the fin" with a slight bit of leeward "railing".
So, I don't think you will see any "twin fin" designs from Starboard (in the freeride design range) anytime soon.
Twin fins do work, sort of, but only when the water is too shallow to allow the use of a correctly sized (for the board's tail width, footstrap offset, rig size, and sailor weight) single fin.
A deeper single fin has less drag, better early planing, and significantly better upwind angle than 2 smaller fins.
The modern progressive rake weed fins (Tangent Dynamics Reaper,
Tekkno Sports Race Weed, True Ames Shallow Water Weed) and the Wolfgang Lessacher Duo Weeds give very good performance (almost as good as a vertical fin design) and certainly better than the twin fin setup, when there's enough water depth to use the correct size.
These are not to be confused with the traditional very swept back (> 45 deg.) weed fins that stick out behind the board.
Hope this helps,

5th December 2006, 10:05 AM
I agree with Roger.

Twin fins are better under limited circumstances of sub-optimal fin choice in the single fin board because of wind / depth conditions. In that circumstance, they are demonstrably superior.

I would point out that there are only a very few shallow / wide fins for single fin boards, and I'm not certain how they would compare.

Certainly, experience shows that the fastest configuration is the minimal fin that allows planing, and the highest efficiency is a high aspect ratio pointer. So when water depth is not limiting, I can't imagine a single fin not being superior.

Just ask yourself....when's the last time Boeing made a biplane?


5th December 2006, 07:31 PM
Haha :) I can se your point. It would be quite funny to see a plane with two wings on each side.... Well I will stick to my Carve and F-type boards with large fins and walk the distance to the deeper water.

Thanks for all the answers.

Best regards,


5th December 2006, 10:12 PM
Hi Niklas,
Unless your winds are straight onshore, try learning to sail your board backwards (fin first).
It's easier than you think it might be, and when you sail with your weight in front of the mast foot, the tail is lifted quite a bit and you can sail pretty well in very shallow water.
The Formula guys all do it, and I've found it to be quite easy as long as the wind supports going away from the beach or back to the beach on your way in.
Hope this helps,