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Old 3rd October 2007, 07:32 PM   #1
Floyd
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Cool Sail Range and Weight

How much does rider weight influence sail range for any given board ???


Eg)In Acid range the 80 is quoted as 3.5 to 5.5. I`m looking for a board to use with sails from 3.7 to 5.4 . It looks perfect.However my weight is 102kg; so I suspect 80 will be too small.The 86 with the 3.7 is below its bottom advised limit.Pretty sure everyone will say it will be ok and I`m sure it will but if I was using sail range as a guide to purchase I should be buying the 80?!(Which I`m not)

To be fair I`ve only used 3.7 twice in last 2 years so boards performance at this size is pretty irrelevant but I think you see point I`m making.

ie)My weight suggest I should be getting k96(or similar); my sail usage suggests A 80 ????
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Old 7th October 2007, 06:48 AM   #2
Screamer
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Manufacturer's quoted range won't work for all sailor's weights and in all conditions. I believe most manufacturers stretch this range a bit (I mean, who would choose a 75cm wide iSonic122 to sail with a 6.0 ?)
A 60 kg sailor could get away with a max (5.5 or even larger) sail on a particular board, whereas you couldn't @ 102 kgs. But then again, when it's howling, there's no way a lightweight can hold things together with a 3.7 (on the same board) the way you could.
Btw, you are asking an awfull lot of one board if you want to use it with a 3.7 and a 5.4 (luckilly 3.7 days are really rare as I understand).
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Old 7th October 2007, 03:20 PM   #3
Ola_H
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Rec sail sizes re for "medium weight" sailors. So, as you suggest, you need to be on a bigger board. On the other hand, even 5.4 weather for you will mean rather windy day (with corresponding rougher water state) so you should not go to big either. Personally I think the K96 indeed will be the best compromise. It is a real wave board shape, but with a wider tail and wider shoulders. The board also has pretty good control, and I think 4.5 will still be within the sweet spot for you and 3.7 will be fairly OK too. You might want to add an extra fin or two to squeeze the biggest possible range out of the board.
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Old 7th October 2007, 05:00 PM   #4
Floyd
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Hi Screamer/Ola
Thanks for replies.
On question of my board choice I tried (had) a k95 and found it only marginally better (if any)than present 105 litre board in 5.4 weather and it was a bit big (even with my weight on it) in 4.7. Hence why I`m thinking A 86 (or k89).Present board goes down to 5.4 fine; so I agree with Screamer ie)New board needs to work below 5.4. (ie 4.7 and 4.2 and occasionally 3.7)
On a more general note point I was trying to make was could manufacturers be more specific with weight and sail range relationship. If I chose board from sail range guide I`d be buying an Acid 80;it has in theory perfect sail range for my smallest board.If I chose it purely on volume(width) I`d be buying a k96.

Suspect most 95k+ sailors are in similar dilemna.

Putting it another way ; what is recommended sail range for PA 86 with 102k rider ???
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Old 8th October 2007, 02:32 PM   #5
davide
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Quote:
Originally Posted by Floyd View Post
.
Putting it another way ; what is recommended sail range for PA 86 with 102k rider ???
Do keep in mind that sail size is also roughly linearly related to weight and in respect to a 170-80 pounds sailor you can hang on more sail. If you sail mostly in the 15-20 miles/hour range (call it a 6.0 for you, call it a 5.0, on a wave board, for me at 150 pounds) you will need a 90-100 liters board. If you sail in the 20/25+ miles/hour range (5.0 and below) you can use a 80-90 liters board. That is ... an Acid 86 or the Kombat 89 might be sort of ok in your marginal 5.5 conditions but fine in powered up 5.5 or when you use a 5.0 and below ... I suppose

Last edited by davide; 8th October 2007 at 02:39 PM.
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Old 8th October 2007, 03:15 PM   #6
Floyd
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Hi Davide
Not sure sail size and weight are linear.Infact pretty sure they aren`t.
In lightish winds;or possibly in a particular given wind they could be.But as wind increases the difference in sail size has got to diminish.
A doubling in windpower quadruples the amount of energy/power available.
In lightish winds I find I need about a metre more than average (ie I`ll have a 7 on ; 75k mates on a 6 but in strong winds (ie 4 metre ish) I can get going with pretty much same size sail .
I`ve pretty much got it sorted for sail sizes/wind. But struiggling a bit on smallest board choice.
Agree with you re Acid 86/K89 though.
Thanks for repy.
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Old 8th October 2007, 05:06 PM   #7
Ray Timm
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I would go for the PA86 at your weight. A good friend of mine who weighs 104 kg uses it with everything from a 5.8 to a 4.5. My PA80 feels too small for him unless the wind is up to the point where he needs a 5.0. Compared to my 84 kg, my friends who are over 100kg tend to use the next sized larger wave board or B/J board and at least one size larger sail until the wind is up over 28-30 knots when we can end up on nearly the same gear although I prefer boards closer to 70 liters when the wind is really strong.
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Old 8th October 2007, 10:23 PM   #8
davide
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Quote:
Originally Posted by Floyd View Post
Hi Davide
Not sure sail size and weight are linear.Infact pretty sure they aren`t.

Agree with you re Acid 86/K89 though.
Thanks for repy.
About linear. Wind force is exponential but locally a linear approximation is effective.

Try: 0.65 x Weight (Kg) / wind speed (meters/sec)

For example, at 8 meters/sec (15.5 knots) I am on a 5.5 square meters sail, at 12 m/sec (about 23 Kn) I am on a 3.7 that underestimate a bit the size but is not bad as an estimate.
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Old 8th October 2007, 11:43 PM   #9
Floyd
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Hi Davide
See your reasoning but I think you are doing what we all do at times; ie bend the figures a bit here and there and then say well it nearly fits.
First of all from an energy point of view
A 12m/s wind contains root 2 (1.41) times 50% (ie difference in linear speed) as an 8m/s one.(ie a 12m/s wind is 50% faster than an 8, so it contains about 70% more power.)(ie x 1.7 )

In 15 knots I would be on around a 6.5 (or even 6.2)
In 25 above figures would give me a 4.2 (ie 6.5/1.7)(for equal power ???)
Which is about correct.(Id be getting overpowered with 4.7 and thinking about 4.2)
This model would also show sailors coming towards similar sized sails as wind gets stronger. (which is one of few facts we have.)

PS Your equation gives me an 8.2 metre in 15 knots ?? and a 5.5 in 25. (Both out, my biggest sail is 7 and I sail from around 13 knots)

It just cant be linear when doubling wind quadruples power ! Its what makes fin and sail choice so interesting.
Take care.
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Old 9th October 2007, 12:05 AM   #10
davide
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Quote:
Originally Posted by Floyd View Post
Hi Davide
See your reasoning but I think you are doing what we all do at times; ie bend the figures a bit here and there and then say well it nearly fits.

In 15 knots I would be on around a 6.5 (or even 6.2)
In 25 above figures would give me a 4.2 (ie 6.5/1.7)(for equal power ???)
Which is about correct.(Id be getting overpowered with 4.7 and thinking about 4.2)
This model would also show sailors coming towards similar sized sails as wind gets stronger. (which is one of few facts we have.)

PS Your equation gives me an 8.2 metre in 15 knots ?? and a 5.5 in 25. (Both out, my biggest sail is 7 and I sail from around 13 knots)
It is a wild approximation, if you could sum up variables such as wind force, board lift, water conditions, sailor weight, sailor height (think leverge), and ... sailor preferences (do you like to go overpowered or powered up) in 1 silly linear equation ... well, quite a good eqn it would be. However, center the equation on your sailing style (i.e. change the 0.65 coefficient to match your 15 knots = 7 suqare meters) and the eqn will work ok ... in the sense of giving an idea of ballpark weight related differences (not to actually pick up a sail at the beach!)

Individual variation can be a very large component. Two days ago I was out with my Acid 74 with a 4.7 SO alternating with my W52 with a 5.6 twin-cam: just for fun, same wind conditions, if I was racing slalom I would have been probably on a 6.0+

Last edited by davide; 9th October 2007 at 01:46 PM.
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