View Full Version : Weed fin for Isonic 101

4th August 2009, 02:49 PM
Hi Guys
I have a favorite spot here in Sweden where the water is very flat even i high wind, perfect for some Isonic blasting. But at some wind angles it gets so much weed in the water, sailing with out spinning out is almost impossible.

So I need a weed fin to my iSonic 101 which I use with North S-type 7.8 and 6.6. I weigh 75 kilos. I've been looking at the Lessacher Chamäleon but need advice on fin length. Would 28 cm be the right one?

6th August 2009, 05:18 PM
I have ordered the 28 cm which should be perfect with the 6,6 sail. I will try it on with the bigger sail as well an let you know how it turns ut.

7th August 2009, 01:11 AM
Hi bigblue,
You might be better (faster...shed more weeds) on the iSonic 101 with the Lessacher
Duo vs the Chamäleon.
I have not tried the Chamäleon but I do have a set of Dou weeds (28/32/36/40) and they are really wonderful on the iSonic boards.
28 should be very good with your 6.6 and maybe the 7.8.
Buying a 28 and 32 cm Lessacher Duo's would pretty much cover all conditions you are likely to sail on the iS 101.
Hope this helps,

10th August 2009, 02:58 AM
Roger wrote that what I think. Thank you. The weedfins are rake 45°, I worked
for the Speeder rake 30°. Very fast, weed is not perfect,but better than the most
The 22cm made with Thomas Döblin 49,99 knots topspeed. 93 km/h. We dream from
100 km/h. He used the fin the first time. For 101 liter is 28cm,rake30° big enough.

10th August 2009, 09:16 AM
Hi guys, I am looking for a smaller fin for my IS 101 2009 for speed other than the stock Drake one, and now i see that there is one called Lesacher, could realy a 28cm fin manage an IS 101 liter with 45.4cm tail wide and with 6.6 or 7.8 sail? Can someone clarify us all that? Isn't such a fin too small?

10th August 2009, 11:07 AM
Hi Willy.
You would need to get a Lessacher Design Duo 28 (or if you don't have weeds, try the 30 deg/ LE Rake Speed Fin).
These are not your normal fins.
They feature Wolfgang's "assymetrical foils".
There is a convex (positive) foil at the top on one side and a concave (negative) foil
on the other side, and then about half way down the foil the covex/conve foils are reversed to the other side. On a weed fin, this means that any weed that lands on the LE of the fin and is symmetrical (balanced on both sides and the kind that really sticks and causes spinout problems) the asymmetrical foil causes them to "flap" on the concave foil and come off easily.
Something about this "asymmetrical foil" system prevents alot of spinout found with purely symmetrical foils.
The guys are really going fast on them, and I will back up Wolfgang's claims on the weed fins as that's been my experience. Try a 9 m2 + formula sail on a 40 CM Lessacher Formula Duo Weed and it will make a believer of you.
The 28 cm is only too small if you "jump on it" too soon, before the water gets going by fast enough.
Otherwise, 28 cm on a slalom board can be very fast, and spinout free.
Only way to really see how good they are is to buy one.
For weeds.... get the 45 deg LE Duo 28.
For Speed.... get the 30 deg. LE speed fin 28
Suffice to say they pretty much do not spin out and they are very fast (check the number of GPS Speedsurfing sailors using them in Holland and elsewhere.
Hope this helps,

12th August 2009, 01:22 AM
I've got a Lessacher Carbon Duo Weed 28s, which is a bit more svelte in outline, as it offers somewhat less area overall. Although I have been using it on a Mike's Lab, the board is of a similar volume, and I'm the same weight as you. I use this fin up to a 7.1 with complete confidence, without any spinout or crabbing, and it jibes so well. It could be that the larger standard Duo Weed 28 would work quite well with a 7.8, as Roger has recommended.

I also have a 24cm Chamaleon that I've used with the 7.1, and while it had excellent drive, free of spinout and crabbing on reaches, it didn't like to be driven hard into jibes and would tend to break loose if suddenly pushed too much. But to be fair, it's a very small fin for such a large sail, and I'm sure that a larger size would most likely solve the problem.

No doubt, whether you go with the Duo Weed or Chamaleon, I think that Lessacher is offering premier weed fins like no one else out there. You're clearly on the right track.

12th August 2009, 01:54 AM
Thanks Steve. I just got the fin today. Hope to try it out with in the next days. When I tried to fit the fin in the box of my Isonic, it only slid in halfways, and when pulling it out a tiny crack in the gelcoat was the result. Will this let water into the board itself or are there additional layers preventing water from entering the core?

12th August 2009, 11:16 AM
Hi big blue,
Get out your file and some abrasive cloth as well as a bar of soap and "fit" your new fin
into the iSonic finbox.
As far as the tiny crack in the gelcoat, the finbox cassette extends at leas 1/2" in all directions from the actual fin cavity so you should have no worries about anything leaking around the fin box.
The finbox cassette is glassed into the rest of the bottom of the board and is glassed to the deck as well.
A little white touch up paint or nail polish the right shade of white and the area around your fin box will look as good as new.
Hope this helps,

12th August 2009, 11:54 PM
Phew. OK, at least I know how to spend the evening :-). Thanks for your tip on how to get a perfect fin fit.

13th August 2009, 03:03 AM

Which fin and size did you ultimately decide on?

13th August 2009, 03:34 AM
I bought a 28 cm Lessacher Chamäleon since we have some serious weed sometimes - like today. But since the fin was to big and I did not have the right tools for the job, I had to ride with my ordinary MFC 34 SL and stop every second leg to remove the vegetables.

13th August 2009, 10:07 AM
Hi Big Blue,
What tools do you need? A double cut flat file, a bar of soap for marking the high spots,
and a piece of about 180 grit abrasive cloth.
Check some of my older posts on fitting fins. Do a search on "Fitting Fins".
If you use the soap (rub it on the fin root to see where the root is tight in the fin box)
it should only take a few minutes and a few strokes with your double cut file to get the Chameleon to fit into your isonic.
The abrasive cloth is simply to fair in where you file off the high spots.
Hope this helps,

14th August 2009, 02:00 PM
Thanks Roger. I got the job done, but once in place i could not tighten the front because the bolt in the fin was not correctly thread. And in addition i noticed a small indentation in the back of the fin base. About 1 cm wide and 2 mm deep. It was as if there was not enogh material during the making. So I''m taking the fin back to the shop for replacement.

16th August 2009, 11:36 PM
Just a quick report from my first session with the new weed fin. We have had a great combo on the Swedish west coast today – Sunny, Sunday and steady winds (Force 6). I went blasting in our bay and for once I was weed free. What a relief. The jybing and the speed was very similar to the runs I've had with my standards MFC 34 SL. I used it with a 6.6 North S-type and my 101 Isonic. It never lost the grip, but when we went out in the chop fully powered up, you could feel the tendencies as it sometimes slid 1-2 inches down wind. The fin sort of let you know that this is about as much as it could take. But all in all, I'm happy.

5th October 2009, 04:12 AM
I tried a Lessacher le duo weed 28 cm for my isonic 101 and P7 Ac1 7,2m2 sail in 20-35 Knots wind this weekend here in Denmark. The conditions were mixed from very flat water to full choppy open ocean. I must argue that this weed fin really rocks! I have not experienced any spin outs with this 28 cm fin and its blazing fast crosswind and downwind, even faster than many of the G10 slalom fins that I have tried from 36 cm - 40 cm. Generally 28 cm fin goes for speed and are only reliable for downwind, but lessachers fins go well even upwind when water is not too choppy. Even in choppy condition, the fin has good grip and control, overall my isonic was running very fast and controlable.

7th October 2009, 12:35 AM
Hallo Bigblue! Pardon me,what happend with the Chamäleon fin , should not be.Was the fin from Tekkno? Wolfgang

7th October 2009, 12:44 AM
Hallo Mr. Glensdale! You got a pic of the rake 30° fin. Thomas Döblin made 50 knots
topspeed with a 22cm fin. She is 28cm long.If you are fast, no problem with weed.
Thank you: Wolfgang

12th October 2009, 03:36 AM
Hi Wolfgang, I changed my Tekkno Chamäleon fin at my local dealer. They looked at the fin - no questions asked. Also the one I have now has a small indentation at the back of the fin base. But it is minor and I was soo looking forward to going surfing.