so one piece of software uploaded data and i have saved it. i then tried to open it in the G7towin program but it didn't make any sense!!

hopefully I can find a users guide.

i have 1 v shape. that's it!

Thanks for the advice, I will try all these things on my lunch break....

Cheers

I'm not a total expert, but oversheeting is no good for speed. You want to bear off with the gust, and hang as much leverage on the sail as you can with maximum power in the sail. So set up is critical that you have set up mast foot position and have boom height and harness lines in good positions for those broad reach runs. Then technique comes into it, coz u gotta have leverage to direct power through the board, so stance, weight distribution and leverage come into it. Keep experimenting till you sart hitting 33's and 34's in same conditions. If however, you already have set up and technique dialled, then you may be maxing out in what is possible for your equipment and water conditions. However, over-sheeting does not sound good!!

Here is a real good explanation by Finian of how to go about it

http://www.boardseekermag.com/technique/index_021.htm

Click on lets talk speed link

or here is the direct link which you will have to cut and paste direct into your media player URL (you can save from there)

www.boardseekermag.com/moves_and_movies/speed/TECH_021_FINIAN_SPEED512K_Stream.wmv

quote:

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Originally posted by hardie

OK, this thread is for speed advice.

The speed guru is not me, but the community of seabreeze windsurfers around Australia. So put your speed questions here, and anyone that feels they can help, can answer!!!


I'll just start off with something on sails, that people have reacted to, questions such as how do you rig a sail to go fast, this is what I put on another thread:
news for you he switch to maui sails
Wanna know what a fast sail looks like, check Martin Van der Meurs, rig when he did 49.4 knots, bottom full, top flat to inverted, almost like an s shape:

http://www.naishsails.com/news/news_030107.php

That is from the naish website, so they hold 2 world records.

All the Australian records are held by KA Koncepts, so maybe some of the KA people can talk about their sails.

Neil Pryde have their RS series.

And other brands have theirs, so please all feel free to contirbute.

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Define old.

Race sail wise most sails post 92 were extreme loose leach- downhaul until the leach was loose similar to sails now. Around 94 pryde began using hollow leach to induce (static) twist, this was continued with VX which did not require the leach looseness of earlier models, gaastra and north at the same time reduced the amount of looseness required with progressive twist.

All evolved into more dynamic twist- more or less this continued up to 2000 (the s*** tip revoluition), off the wind however the pro's still piled on the downhaul with anything from tape to stickers and hacksaw blades being stuck on the leach to stop the sail shaking apart on the upwind leg.

Prior to 92 are we talking cammed or not? Since most sails weren't cammed follow the rules for rigging raf sails. Cammed you are own you're own, most those that I tried were dogs which i'd rather forget... with one or two exceptions.

Sails have evolved pretty dramatically, i was bewildered very early in my sailboarding life that the wind would suddenly try to slam me down from opposite sides of the sail, that was with brand new sails for the time ('94 aerotech ultimate). Now you can probably go twice as fast on wavesails and you still wont get backwinded.

My recollection of race sails from 1987 to 1993 was that they did not have loose leaches at all. I think a Tiga Slalom World Cup sail was similar to the NP World Cup Racing series and would have been tight leached.
Dont try to downhaul a tight leached sail to get a loose leach, it will not happen, you will break the mast or sail before you get anything resembling a modern setup.
Tight leaches made for very powerful sails, but smaller windrange.

JB

Yeah, symmetrical fins are the same on both sides and asymmetrical aren't






oh, you meant a serious explanation

Anyone know how fast a Kinetic Centurion 110ltr, 247 by 77 would be? i know you can't tell me exactly, but would it be quick?!? Is it any good as I'm thinking of buying one for lighter wind windsurfing.

Cheers

Fair enough, it's for 6.8m - 8.7m weather...

I just need a faster board for those flat days and I don't want to spend a lot of money!

Hi Hardie this is copied off Mals site and gives a far better explation than I could give

An asymmetric fin allows the same size fin to produce more lift for roughly the same amount of drag. This directly improves the lift-to-drag ratio, making a more effective fin. See the following graphs which show a comparison between a symmetric slalom foil in black, and the same foil in red with a coefficient of lift of 0.2, making it an asymmetric.

Lift to drag comparison between two sections. The black line shows the lift-to-drag of a symmetric section. The red line shows the same foil applied to a cambered centerline, making an asymmetric section.
Lift to drag relative to angle of attack. Notice how the asymmetric section makes lift even at 0 and negative angles of attack. So typically an asymmetric fin will not crab the board sideways as much as a symmetric section.
There,s more info at www dot intellimass dot com

quote:

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Originally posted by kato

Hi Hardie this is copied off Mals site and gives a far better explation than I could give

An asymmetric fin allows the same size fin to produce more lift for roughly the same amount of drag. This directly improves the lift-to-drag ratio, making a more effective fin. See the following graphs which show a comparison between a symmetric slalom foil in black, and the same foil in red with a coefficient of lift of 0.2, making it an asymmetric.

Lift to drag comparison between two sections. The black line shows the lift-to-drag of a symmetric section. The red line shows the same foil applied to a cambered centerline, making an asymmetric section.
Lift to drag relative to angle of attack. Notice how the asymmetric section makes lift even at 0 and negative angles of attack. So typically an asymmetric fin will not crab the board sideways as much as a symmetric section.
There,s more info at www dot intellimass dot com

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If I understand this correctly............. It seems to imply one can use a smaller fin, with less drag but improved lift and drive??? So the cost must be that coming back on the opposite tack must be inefficient?? Is it harder to sail back?

Hi Hardie,yes upwind performance can suffer with some fins,but the downwind makes up for it and more.Assy fins don,t spin out unless you do something stupid with them like I did last week.You can also push really hard on them and get a lot of the board out of the water.BUT you can also do so really good times on symm fins.Find out what you like and go fast.
Assy fins have a different foil shape on each side. ie the wide point on the fin may be at a different point.One side the wide point might be at 37% on the other at49%. Hard to explain without drawing it.Read the posts under fins it might explain it better.30/40wsw at the pit tommorrow might see if the theories work

Yep Those fins of Mals really do work in both directions.
Of coast your not going to go as fast on port tack but you can still push them up wind. Unfortunately up here in QLD all the fastest spots are port tack bummer.