my understanding is that it was an accidental find
by Barry Spanier and Bruce Peterson together

in my notes it was with Gaastra testing ADTR in the desert in 1987
without Barry

joewindsurfer.blogspot.com/2007/03/history-of-windsurfing.html

That would be J. P. siren at the Weymouth Speed Trials in 1982, which I think he won. Large roach with massive twist, when a lot of competitors had pin-head sails. Sailmaker was ITV

I find here that Berry first design cutaway 1984 which was first way how to make loose leech.

www.americanwindsurfer.com/articles/monty-spindler-maryland-yankee-in-europe/

soon we have 10 inventors

Pacey said..
That would be J. P. siren at the Weymouth Speed Trials in 1982, which I think he won. Large roach with massive twist, when a lot of competitors had pin-head sails. Sailmaker was ITV

That sounds right. I actually remember Gaastra as being a bit late onto the extreme twist idea, perhaps because it's not so important in World Cup racing.

Nubie said..
I find here that Berry first design cutaway 1984 which was first way how to make loose leech.

www.americanwindsurfer.com/articles/monty-spindler-maryland-yankee-in-europe/

But a cutaway wasn't the first way to make a loose leech, per se. Look at the amount of twist in these 1973 sails;



An open leach arguably isn't the "best" way to make a sail, anyway. It's the "best" in certain ways, in certain conditions, for certain types of sailing. If you change the conditions, the board style, the course style or the technology then it can be quite slow.

By the way, JP Siret's sail was before the cutaway. I can remember us looking at pics of it and saying "who would think that would work?" but realising that the simple fact was that his times showed that it DID work. However, tight leaches continued to dominate for some time in some areas of the sport, because they are a damn good way of generating maximum power for a limited area a lot of the time. JP was speed sailing, but that was a fairly small area of the sport at the time and required different sail designs than the slalom, Raceboarding, course racing etc many people were doing.

Sails of that time were pretty heavy and booms and mast were floppy, so adding area to get a floppy leach had obvious drawbacks. We also tended to sail in lighter wind a lot of the time, when a big floppy leach was just slow. We were very familiar with them because the first fatheads often flopped open in strong winds. And even slalom was often surf slalom, where a lighter sail and good low-end acceleration were important.

Nubie said..

Chris249 said..

Pacey said..
That would be J. P. siren at the Weymouth Speed Trials in 1982, which I think he won. Large roach with massive twist, when a lot of competitors had pin-head sails. Sailmaker was ITV

That sounds right. I actually remember Gaastra as being a bit late onto the extreme twist idea, perhaps because it's not so important in World Cup racing.

J.P. siren was sail designer for which brand?

What about cutaway?

Sorry, Jean Pierre SIRET, a sailor from Noumea.

Sail brand was ITV.

Sure it wasn't the Sydney 18 Footers ?

Early 80's, super bendy masts, I reckon that was the start of the "twist".

Optimist sailing dinghy with their gaff rig sails.

Well the question is a bit strange.
It is true that at some point windsurf sail designers realised they have been selling sails with tight leeches for many years, and that loose leeches could be faster or give better handling when over-powered.
But the 'loose leech' is connected with sail twist and with flat-cut sail heads - which had already existed for years in yachts and in racing dinghy sails.
So what actually happened is that someone realised our windsurf rigs could become more sophisticated and that mast bend (and therefore sail shape) could be controlled by downhaul tension. The discussion then gets more complicated.
So, my point is that you are possibly looking at this topic from a limited point of view.
The trend towards loose leech sails happened in all our rigs as a period issue, but recently the designers have backtracked because 'wasting' sail area at the head by sheeting it out is not always a good thing - and indeed freestyle sails and wave rigs are often set more tight-leeched nowadays, meaning we plane earlier with smaller rigs. For example, you won't find much luff panel tension in the rigs used in Bonaire for the PWA freestyle event this week. The tight leech is good for acceleration, and for maximising power generated from a small sail area.
In racing, light wind rigs also still have relatively tight leeches for those competing in non-planing conditions.
The loose leach is really at its best for over-sized rigs where the top of the sail is sheeted out as part of a rig 'exhaust' system for boards travelling at fast planing speeds.
Pick your tribe on this one, but the key moment was when we started using downhaul mechanics to control sail fullness and twist.

shoodbegood said..

Sure it wasn't the Sydney 18 Footers ?

Early 80's, super bendy masts, I reckon that was the start of the "twist".

When I was Moth world champion, my light wind sail was quite tight leeched but my windy weather rig had a looser leach and was cut much flatter to twist off at the head. (1970s).
But it's also key here to understand what you can do with a stayed mast on a dinghy or yacht, and what you can do with the un-stayed windsurf rig. In windsurfing our only mechanical controls are downhaul and outhaul, which work in conjunction with mast stiffness and mast bend.

^^^ Her unfortunate nick name was "Loose" Leech.

Basher said..
Well the question is a bit strange.
It is true that at some point windsurf sail designers realised they have been selling sails with tight leeches for many years, and that loose leeches could be faster or give better handling when over-powered.
But the 'loose leech' is connected with sail twist and with flat-cut sail heads - which had already existed for years in yachts and in racing dinghy sails.
So what actually happened is that someone realised our windsurf rigs could become more sophisticated and that mast bend (and therefore sail shape) could be controlled by downhaul tension. The discussion then gets more complicated.
So, my point is that you are possibly looking at this topic from a limited point of view.
The trend towards loose leech sails happened in all our rigs as a period issue, but recently the designers have backtracked because 'wasting' sail area at the head by sheeting it out is not always a good thing - and indeed freestyle sails and wave rigs are often set more tight-leeched nowadays, meaning we plane earlier with smaller rigs. For example, you won't find much luff panel tension in the rigs used in Bonaire for the PWA freestyle event this week. The tight leech is good for acceleration, and for maximising power generated from a small sail area.
In racing, light wind rigs also still have relatively tight leeches for those competing in non-planing conditions.
The loose leach is really at its best for over-sized rigs where the top of the sail is sheeted out as part of a rig 'exhaust' system for boards travelling at fast planing speeds.
Pick your tribe on this one, but the key moment was when we started using downhaul mechanics to control sail fullness and twist.

+1 on what he ^ said!

Pascal Maka, or whomever his sailmaker was at the time had something figured out by 1986. Maybe he took inspiration from Jean Pierre SIRET in 1982? If you watch this video - as I have dozens of times - you can see his sail has elements of much more modern sails in its shape. Flatter twisted head for sure. It is in stark contrast to most of the other sails in the video. He also broke the world record.

Jean Piere Siret is a good mate, I remember, back in the days, telling him : "JP, your sail would look better with a loose leech"
So I guess that makes me the inventor !

1990, monofilm was around and loose leech was accepted.
Gaastra sails of 1987 were tight leeched, but '88's were different with more luff curve and could be downhauled to loose leech but wasn't advertised as such.
Got dumped by Gaastra for '89 so switched to Rushwind dacron sails which rigged and sail BOTH ways so I had no clearcut idea which was best. Winds constantly change while you're in the water, and it takes time to sail back, locate your quiver, dodge the questions, and get back out there.