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Old 19th August 2007, 08:20 AM   #1
Randy
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Default Serenity Speed!

I realize this isn't exactly as scientific as using GPS, but today a friend chased me (on Serenity) on his jetski. He clocked me out at 18 mph on the quickest run! I was sailing 7.4 Aertoech Zenith, using the big fin and there were a few, but not a lot of whitecaps. A moderate amount of boat chop. We did it a number of times, with results in the 12-15 range frequently. What speeds have people been getting with GPS?
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Old 20th August 2007, 08:18 AM   #2
vikingsail
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Using a 42 cm weed fin I have reached speeds as high as 14 mph with an 8.0, but looking back at the GPS data the normal terminal speed for the board appears to be 12 or 13 mph. I have followed Roger's suggestion and have moved the mast foot forward, this does seem to keep the stern from going under. I want to do more tests with a 35cm weed fin. (corrected fin size)

Last edited by vikingsail; 20th August 2007 at 11:47 PM. Reason: wrong fin size
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Old 20th August 2007, 09:42 AM   #3
steveC
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Hi vikingsail,

I have been quite interested in the use of weedfins on the Serenity, as weedfins are a prerequiste in the locale where I would use the board. I'm curious about the brand of your weedfins.

The one thing that I have noted over the years is that all weedfins aren't created equal, irrespective of their cited length, and this opinion comes from a long history of experience with True Ames fins. I've been particularly impressed with two entirely different designs, but the one that I'm hoping will be most meaningful for the Serenity is a Lessacher Duo Weed asymmetrical. I've got a couple of them (a small version 28cm and a standard 34cm), and it's remarkable how much power and directional drive they offer for their relatively compact sizing.

I'm currently honing in on buying a Serenity, and I'm very hopeful that the 34cm will serve my needs in concert with 7.1 and 8.3 sails. Roger's past impressions seem to support my direction here, but I remain curious about the experiences of others like yourself. I should emphasize that I have no intention of ever being able to use the 70 and 40cm sizes provided with the board.
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Old 20th August 2007, 02:00 PM   #4
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SteveC, in the Technotes for the Serenity posted on the new *board site, Tiesda You wrote that a 40 cm fin is the smallest fin that he thinks will drive the Serenity so a smaller weed fin may not cut it. Maybe you can get someone to try it before you buy.

Jay
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Old 20th August 2007, 05:20 PM   #5
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Hi Jay and Steve,

Come to think of it I haven't tried the Serenity with weed fins. The minimum size mentioned in the tuning tips section would be more about fin surface area to be truly accurate. 40cm was used though because the convention with windsurfers is to use fin depth as the main measure of fin size.

Since weed fins are heavily raked, it's very possible that you can go smaller than 40cm in depth, so long as the surface area is adequate.

I remember trying a tiny Slalom 36cm fin (none weed fin) and it was a total disaster.. The board even refused to move forward so I kind of had to swim it back in. Well given that it didn't go forward it wasn't that long a swim but I found it funny since it was the first time a board we designed didn't even work in its most fundamental sense. Pretty embarassing for a designer..

Tiesda
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Old 21st August 2007, 12:22 AM   #6
steveC
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Hi Jay and Tiesda,

My Lessacher Duo Weed 34cm is probably raked at 40 degrees and it packs in quite a bit of surface area. Measuring it along the leading edge from the base to the tip is approximately 50cm, and surprisingly, it offers about the same drive as True Ames SB Weed 20" (fin depth) which I had that is raked at 45 degrees. I think much of the magic of Lessacher's Duo Weeds can be attributed to the asymmetrical foiling. Also, I find that it works extremely well with the 8.3, offering particularly strong drive and upwind ability even in the lightest winds.

I should probably do a search of Roger's past comments regarding use of different weed fins with the Serenity. If I recollect correctly, he has a Lessacher Duo Weed that was no larger than a 36cm, and he indicated that its performance was quite acceptable in concert with a 7.5 sail on the Serenity. I definitely remember that he was very happy with a Tangent Reaper 42cm, which exhibits a very similar design planform to the True Ames weedfins.

Maybe, if Roger is available, he will offer his thoughts about the Lessacher Duo Weeds that he has.

In any case, my worst scenario would be the need to buy an even larger weedfin, but I still remain optimistic about the 34cm.

Tiesda, just last week Jean-Marc posted your tech comments on the forum here, and I was especially stoked by your parting words about the Serenity design. It's very telling that you consider it to be one of your proudest accomplishments in your career as a shaper/designer.
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Old 21st August 2007, 01:49 AM   #7
Jille
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With GPS I've measured 27,5 km/h, as a 2 sec. max. speed on 5 different runs.
About 15 knots wind, using 9.0 Gaastra Vapor and the Shallow 41cm fin.

I've tried to ride waves, etc., but this was my max. speed.

At that point the nose came up too high (past the baseplate) and I couldn't get it down.

So if anyone was faster, please post youre solutions here.......

http://www.gps-speedsurfing.com/gps....mnu=2&val=4190
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Old 21st August 2007, 09:32 PM   #8
Jean-Marc
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Quote:
Originally Posted by Jille View Post
With GPS I've measured 27,5 km/h, as a 2 sec. max. speed on 5 different runs.
About 15 knots wind, using 9.0 Gaastra Vapor and the Shallow 41cm fin.

I've tried to ride waves, etc., but this was my max. speed.
I guess this is the famous topping up speed of such a hull, i.e., the more windy, the less efficiencient the ratio hull speed/wind speed can become (i.e., 0.93 with your 90 kg weight, a 9.0 sail and 15 knots of wind).

Quote:
At that point the nose came up too high (past the baseplate) and I couldn't get it down.
You're entering foil riding territory. Wait 'til the nose come up past the carryhandle and you start tailwalking da big bertha (not the fastest board pitch, obviously) !

Quote:
So if anyone was faster, please post youre solutions here.......

http://www.gps-speedsurfing.com/gps....mnu=2&val=4190
Not that I'm aware of. Rémi has done ± the same at Vmax 14 knots with an Overdrive 11.0 sail in 7 knots of wind (ratio = 2.0) whereas I've done a Vmax 12 knots with a CodeRed 11.0 in same wind (with the big 70 cm fin; ratio 1.71).

Cheers !

JM
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Old 22nd August 2007, 07:03 PM   #9
Jille
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Quote:
Originally Posted by Jille View Post
So if anyone was faster, please post youre solutions here.......

http://www.gps-speedsurfing.com/gps....mnu=2&val=4190
This might be confusing!!!

The idea was that solutions would be given on this forum (Starboard), the link was only for details about my session!

Anyway, I hope that someone can give a hint how to go faster!

Altough the Serenity is a great board for light wind and not a speedboard, I always want to know if I pushed it to the max!

And JM: thanks for your input!
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