What makes a sail fast...? is it the amount of cams , is it stability to stay sheeted on ?

or are all sails fast just the top end is better on some .?

what are some of the factors.

do sail companies just wing it ,change that this year ..then change again the next ..

Fast? The pilot and understanding exactly how to rig it for the prevelant winds and using the right board and fin, and understanding how to make the separate parts work together.

Flat water

fastest = best lift to drag ratio in the hands of a windsurfer.

My understanding so far, is that the angle of attack up the luff should be very close all the way up, otherwise the finer entry part will stall when the fuller area is sheeted on. Tip twist acts as a fence to help limit the tip vortex.
The number of cambers doesn't necessarily have a direct relation to sail speed.
It's all about the max power the sailor can hold, reasonably comfortably, with minimum drag.

A fast sail is all about stability and control, coupled with useable power and less drag. It was what we found testing sails on the ADTR when developing Pascal Maka's speedsail that he first broke the world sailing speed record with back in the 1980s. Nowadays as materials and technology have progressed the same principles apply but sail shape has changed to better utilise more stable carbon masts and material that stretches less. Twist also came into play, again as a direct result of ADTR testing. Back in the 1980s Marchaj was the authority and elliptical lift distribution was the mantra. That changed with twisting foils and bell shaped lift distribution is way more efficient. Cambers in the deep power section of the sail are used to stabilise the foil shape while the upper section of the sail is twisted off creating proverse yaw and also reducing drag at the tips and the resulting tip vortices.

Problem with the '85-'89 Gaastras was their inability to hold as big as the twist sails of the time.
So, riders always had to use smaller sizes, not great in big entry events, or in my case, reverse and thin down the top 2-3 battens, and tube the cam battens.
But ADTR did not detect the problem.
Gaastra National team rider, '85-'89.

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LeeD said..
Problem with the '85-'89 Gaastras was their inability to hold as big as the twist sails of the time.
So, riders always had to use smaller sizes, not great in big entry events, or in my case, reverse and thin down the top 2-3 battens, and tube the cam battens.
But ADTR did not detect the problem.
Gaastra National team rider, '85-'89.

Possibly because sails have evolved to deal with the ever-present real world turbulence. (en.wikipedia.org/wiki/Law_of_the_wall )

When you run a truck at speed through relatively still air you eliminate turbulence.

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decrepit said..
fastest = best lift to drag ratio in the hands of a windsurfer.

My understanding so far, is that the angle of attack up the luff should be very close all the way up, otherwise the finer entry part will stall when the fuller area is sheeted on. Tip twist acts as a fence to help limit the tip vortex.
The number of cambers doesn't necessarily have a direct relation to sail speed.
It's all about the max power the sailor can hold, reasonably comfortably, with minimum drag.

Thanks for the come back ..interesting about the power decrepit ...then a no cam or two cam could possible be as fast
as powerful ,I watched a point 7 vid where he tested ACX and his One 4 cam sail back to back ,the no cam ACX was just 1-2 knots slower
but in a race ,thats all thats need to win a race i guess ..

thanks for that roo ..pioneers in the field ,,,amazing ute test ..

The problem with no cams going deep downwind, is a lack of wind pressure to form the draft, so a lot depends on how much wind pressure they need to fully turn on. I think some wave and freeride sailors need the sails to turn off hard when sheeted out. These probably aren't fast downwind. I have a wave sail the opposite to this, it fully turn on with little pressure. But deep downwind it tends to flutter a bit as pressure drops.

rigging a sail correctly can make a sail faster, than when rigged incorrectly or non-optimally

Presentation of the sail to the wind, by holding and positioning the sail correctly and making micro-adjustments as you sail downwind

Poor man's wind tunnel. I once owned a Gaastra 10.0 cambered sail that had been developed with the trucks in the desert. The sail was ok but was definitely speed limited. It had a lot of low end grunt, but no twist and no top speed capability. Heck, it even had a sticker on it showing the truck-based wind tunnel.

Segler.
One guy on this thread was one of the truck drivers.
Another was a National Team rider for Gaastra those years.

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Tardy said..

decrepit said..
fastest = best lift to drag ratio in the hands of a windsurfer.

My understanding so far, is that the angle of attack up the luff should be very close all the way up, otherwise the finer entry part will stall when the fuller area is sheeted on. Tip twist acts as a fence to help limit the tip vortex.
The number of cambers doesn't necessarily have a direct relation to sail speed.
It's all about the max power the sailor can hold, reasonably comfortably, with minimum drag.

Thanks for the come back ..interesting about the power decrepit ...then a no cam or two cam could possible be as fast
as powerful ,I watched a point 7 vid where he tested ACX and his One 4 cam sail back to back ,the no cam ACX was just 1-2 knots slower
but in a race ,thats all thats need to win a race i guess ..

thanks for that roo ..pioneers in the field ,,,amazing ute test ..

It also does depend on the sailmaker. My ACX clocks faster than my HSM GPS (4 cams) and significantly more so than a Loft switchblade (3 cams). It actually feels marginally less stable but it is faster. I am sure it would loose in a pro level competition against an AC-One, but the point is that there are sails that are faster than others out there. Materials matter. A Hot Sails Maui Speefreak is slower than the sails mentioned above, but if you take materials out of the equation I have no idea what makes a sail faster than another. I am sure there are some closely guarded "secrets".

Too many variables.
Say, 2 Pro slalom sailors. 6'2" 195 lbs., same experience like they are brothers.
Same kit.
You will find ONE tends to be faster most days, while the other can be faster some days.
Why the diff?
Rider counts most.
Gear for sure.
But rider makes the diff.
How many times have you been passed by guys with older gear? Or even gear considered slower than what YOU are using?

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Roo said..
A fast sail is all about stability and control, coupled with useable power and less drag. It was what we found testing sails on the ADTR when developing Pascal Maka's speedsail that he first broke the world sailing speed record with back in the 1980s. Nowadays as materials and technology have progressed the same principles apply but sail shape has changed to better utilise more stable carbon masts and material that stretches less. Twist also came into play, again as a direct result of ADTR testing. Back in the 1980s Marchaj was the authority and elliptical lift distribution was the mantra. That changed with twisting foils and bell shaped lift distribution is way more efficient. Cambers in the deep power section of the sail are used to stabilise the foil shape while the upper section of the sail is twisted off creating proverse yaw and also reducing drag at the tips and the resulting tip vortices.

I always felt that much-publicised testing was for the camera, more than it made any technological sense.

If you understand the concept of apparent wind, then you'll know we can't test a sail in the horizontal plane when it is to be used in the vertical plane.

Depends where you mean fast .
Firing upwind fast is different to top speed off the wind .

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Basher said..

Roo said..
A fast sail is all about stability and control, coupled with useable power and less drag. It was what we found testing sails on the ADTR when developing Pascal Maka's speedsail that he first broke the world sailing speed record with back in the 1980s. Nowadays as materials and technology have progressed the same principles apply but sail shape has changed to better utilise more stable carbon masts and material that stretches less. Twist also came into play, again as a direct result of ADTR testing. Back in the 1980s Marchaj was the authority and elliptical lift distribution was the mantra. That changed with twisting foils and bell shaped lift distribution is way more efficient. Cambers in the deep power section of the sail are used to stabilise the foil shape while the upper section of the sail is twisted off creating proverse yaw and also reducing drag at the tips and the resulting tip vortices.

I always felt that much-publicised testing was for the camera, more than it made any technological sense.

If you understand the concept of apparent wind, then you'll know we can't test a sail in the horizontal plane when it is to be used in the vertical plane.

Gaastra took a few years before they used it for publicity, in the meantime it was a valid testing tool that provided empirical data that showed which sails were fast and those that weren't. The chap that did the software coding was a NASA contractor and they began to show an interest in using it for low speed aerodynamic testing but sadly the project was shut down before that happened. There were many people in the windsurfing industry that wrote it off as a gimmick without really understanding it. The politics within Gaastra meant a lot of the pro sailors feared it would put them out of a job testing and developing sails. Those that did embrace it, like Pascal Maka, reaped the benefits and broke the sailing speed record.

'85--89 Gaastras were actually VERY fast, within it's wind range.
Underpowered, as early planing and quick as anything.
Over powered...no twist, no good if the wind came up. Hence the reversed top battens and cut leeches.

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Tardy said..
What makes a sail fast...? is it the amount of cams , is it stability to stay sheeted on ?

or are all sails fast just the top end is better on some .?

what are some of the factors.

do sail companies just wing it ,change that this year ..then change again the next ..

That's like asking what makes sex good.
Its gotta have atleast 2 cams, a stiff mast and
GIVE IT,GIVE IT lots of down haul.
Its gotta look good when rigged too.
And of course everyone says it the RIDER

I like this...
boards.co.uk/how-to/how-fast-can-we-go-the-science-of-speed.html

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LeeD said..
Too many variables.
Say, 2 Pro slalom sailors. 6'2" 195 lbs., same experience like they are brothers.
Same kit.
You will find ONE tends to be faster most days, while the other can be faster some days.
Why the diff?
Rider counts most.
Gear for sure.
But rider makes the diff.
How many times have you been passed by guys with older gear? Or even gear considered slower than what YOU are using?

Of course the pilot matters ... I used to race a small IOR sailboat when I was young and green and at national level we always placed in the upper mid pack. Than one day the Italian Finn champion joined us and we won the race. There was a biit of luck involved, the boat was ultimately not competitive, but there you go, we were even less so!

It is obvious that the pilot matters, and it also has nothing to do with the question asked: what makes a sail fast, not what makes a windsurf and its pilot fast. Two very different things.

A sail is not fast or slow.
Until a pilot is added. The right pilot, not any old dude from the beach.
Just like a top Formula car, you don't just add up the 2 parts, you have to find the right combination.

Oh, the question.
How to live your life?
What color is best?
What job is best?
Where is the best place to live?
What car should I drive?
No real absolute answer.

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LeeD said..
A sail is not fast or slow.
Until a pilot is added. The right pilot, not any old dude from the beach.
Just like a top Formula car, you don't just add up the 2 parts, you have to find the right combination.

Nonsense. There are faster and slower sails, as there are faster and slower Formula 1 cars. It is beyond obvious that a wave sail will never go as fast as a speed sail.

The question is what makes a sail fast? And within the same specialty are some sails faster than others?

A wave sail pilted by a great sailor will always be faster than any race sail piloted by a good intermediate sailor.

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LeeD said..
Oh, the question.
How to live your life?
What color is best?
What job is best?
Where is the best place to live?
What car should I drive?
No real absolute answer.

A,
Windsurfing
Green .
Retired,
Australia,
Toyota..
Absolute answers .
ps . I'd also accept blue .

A FAST sail will only go as quick as the board that its driving.

Partner them both together and then with a good sailor too and the right conditions and you have the fastest sail.

on any average day a Fast sail will :
one with good shape.
A mast that matches the sails best profile.
A good stiff boom.
Newer the better.
Rigged right.
Sailed to its best potential in the right winds strength.

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LeeD said..
Oh, the question.
How to live your life?
What color is best?
What job is best?
Where is the best place to live?
What car should I drive?
No real absolute answer.

How ever you want.
black/ purple fade
retired
Everywhere gets boring after a few years.
you need more than one

Wind !

Downhaul.

A Wally LT, underneath it