Old 14th April 2008, 05:03 AM   #11
Jean-Marc
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Screamer,

If I remember correctly, you weight 20-25 kg more than me. Whats work for a light weight does not work for a heavy weight in the low wind range for a given board. For a lightweight, you might go beyond the recommended max sail size (which is for 75-80 kg average rider weight). For a heavy weight, you must choose a smaller sail than max recommended. For you, a K86 + 6.9 combo will not work (way less efficiency than for me). To further complicate matters, some board and big sail combo works better than other.
Looks like Mart is highly skilled and light weighted as myself, so what I'm using might give him some clues about what's possible to help him. Looks like Mart doesn't want to go bigger than 80 L and 5.3 sail at all. Fair enough, I'll pass on that.

BTW, I'm using K86+6.9 90% of her sailing time; same about HS105 and my largest sail. Past experience taught me too big a board is just useless ballast for my lightweight. Went from custom HiTech 80 L wave board ( Acid 80) to Acid 62 with 5.4 sail. Went from Carve111 to Kombat 95 to Kombat 86 with 6.9 sail. Went from big raceboard to HS105 with my largest sail. Thinking outside the box is what makes this sport so interesting. For a medium to heavy weight, this is of course another story...

Cheers !

JM
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Old 14th April 2008, 07:07 AM   #12
steveC
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Hi JM,

You raise some interesting points in your last post. I have to agree that my requirements at 70kg can be a whole different ballgame for the notably heavier sailor. I'm glad that you highlighted some things here, since lighter sailors might find different synergies, especially playing with creative fin sizing.

As an aside, I'm still waiting for delivery news on the Serenity I ordered. I have to admit, I'm getting a bit itchy about things. I really hope that Starboard can deliver to Trident, the NA distributor. I still remain optimistic at this time.
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Old 14th April 2008, 10:17 PM   #13
Screamer
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JM

Of course I know a lot about your setup by now (all these years on the forum ;-)
It's just that I've seen sailors make choices based on someone else's experience that obviously doesn't apply to them. Not your fault of course.

I basically agree with you, but here is what I've read somewhere on Boards' forum (I think): a given board always have maximum sail it can carry, more or less REGARDLESS of a sailor weight. I don't agree, but it would be an interesting discussion.
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Old 14th April 2008, 11:45 PM   #14
Ola_H
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Boards mag are wrong in the article you are refering to. Th reasoning was based on a very interesting test (a the whol range of Fanatic Goya boards at the time) but unfortunately the weight range of the testers was very narrow. I would say that while the "sailor weight factor" is not that large, it surely exists. In many cases individual (preferance, techique, etc) may be more important but nevertheless sailor weigh also matter.

As guess would be that 10 kg maybe means something like 0.3m2 in added sail carrying capability for a (wave) board.
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Old 15th April 2008, 12:30 AM   #15
Jean-Marc
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Mart,

Sorry to seriously hijack your post off topic...

Screamer,

Agree it's very difficult to assess the sailing skills of somebody you've never met in real life. However, some queries are obvious, other are not. It's been fairly obvious with Mart.

WRT the Boards mag issue you've raised, I don't know whether a universal board+fin+sail magic formula works for all (I doubt it) but some clear cut past experiences are still vivid in my mind. Here are some of them below:

1) Low wind range is a pretty complex issue : general practice has shown that the more you weight, the larger the board should be at OFO because with a greater leverage over a big fin, one can use a bigger sail.

Drag racing some 85-105 kg buddies on their Formula + 70 cm fin + 10.5-12.5 sail combo has shown me I'm on par with my HS105 + 54 cm fin + RX2 10.6 sail as expected (with the exception of a few degree upwind/downwind that I had to give up to the formula, no surprise here).
Quite unexpected, however, was drag racing a 65 kg buddy on his F158 + 70 cm fin + RS5 9.8 sail : I was planing earlier than him. For my light weight, this is very clear that more width than necessary is useless with a big sail.

For years, I've found out that an ART TNT6 8.2 or NP RS2 8.2 sail provided me the same planing as of 10 knots wind, no matter how wide the board was for me (Ace 309x70 cm x 170 L, AHD DR 72/74/78/GT75/GT85/DF95), HS105). Clear diminishing returns were obtained with Carve 111 + 40 cm racing fin + 8.2 sail: more wind was required, e.g., 11 knots. Why ? The tail is not powerfull enough to transmit all the low power of the racing sail with a high enough efficiency/yield. Shape was key.

2) The same board + fin + sail combo is used in different wind force range between a light weight and a heavy weight. Carve111 + stock freeride 32 cm fin + NP Jet 6.9 sail : I need 12 knots to start and sustain the planing, I'm well powered-up in 15 knots and well overpowered in 18 knots (with increasing downhaul & outhaul). For a 95 kg pal using the same setup, he needs 15 knots to plane, he's happy in 18 and still blasting full speed in 20+ knots wind while I'm rigging my 5.4 sail. Would a fin bigger than 32 cm be better to increase his low wind range? Most likely, yes. Would a bigger sail have been better ? Marginally yes, but most probably, no. From that above, I surmise that a rider need 1 knots higher wind than me for each 10 kg more body weight.

3) Extrapolation to a different type of gear is difficult because there are quite a number of different variables to take into account. Shape details are key. Carve111 + stock freeride 32 cm fin + NP Jet 6.9 sail : planing as of 12 knots for me. Kombat 95 + Select Freeride 31 cm fin + Jet 6.9 sail : more difficult to get planing as of 12 knots for me, felt deceptively sluggish. Kombat 86 + stock freeride 30 cm fin + same 6.9 Jet sail : great, as good as Carve111. Why ? Scoop-rocker line was key.

So, in sum, this is a very complex issue and I'm not surprised at all why a simple matrix output showing the best combo for a given rider weight cannot be written up in a 2-D Excell format : too many variables to account for.

Cheers !

JM
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Old 15th April 2008, 12:43 AM   #16
Screamer
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Mart
I apologize also for this hijacking.... Hope you've got answers you were looking for.

Ola & JM
I've performed similar "tests" with lightweight buddies, and came to similar conclusions (i.e. weight does matter wrt efficient sail carrying).

Bye
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Old 15th April 2008, 12:58 AM   #17
Jean-Marc
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Quote:
Originally Posted by Ola_H View Post
A guess would be that 10 kg maybe means something like 0.3m2 in added sail carrying capability for a (wave) board.
That's an interesting guess. In 35-45 knots winds, I was on Acid 62 + 3.3 sail. Other 80 kg riders were on 75 L wave board with 3.6 - 3.7 sails while a 95+ kg rider was on a 4.2 sail that same day.

However, in light wind, that's a different story. I was drag racing a 105 kg pal in 12-18 knots wind and 0.5 m high swell. I was on K86 + stock freeride 32 cm fin + 6.9 sail but he was on Carve 162 + stock freeride 52 cm fin + freerace 9.5 sail. Same planing threshold between us and same speed. That's a 2.6 m2 sail differential for 40 kg, or 0.65 m2 for 10 kg body weight.

The above figures are for freeriding blasting on a lake. For true wavesailing at sea, this is another story because the thrust moving the board forward is essentially provided by the wave energy (DTL riding) and not so much by the wind, so, too big a sail is a pain during transition. Again, multiple variables at play producing different results. Modelling windsurfing must be a neat challenge for a mathematician I'm sure...

Cheers !

JM
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Old 15th April 2008, 02:44 AM   #18
Ola_H
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Some interesting data (not gonna try to make model for reasons you already mentioned...).

Regarding the K86/C162 example, I think it is also a matter of sailor technique and also that a case of diminishing returns what going or bigger and bigger gear. I would say if get increasingy more difficult to make perfect use of the gear the bigger it gets. But that's of course part of the game.

With my "0.3m2/10kg" I was however more refering to how much more sail a 10 kg lighter rider could put onto a given board (ie not how much more sail a 10kg heavier rider would need to plane).

I agree on that it generally does not help to be on a bigger board than nessecary.
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