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jn1 said..

Matt UK said..
I'm not even going to bother on this site any more, theres far more people on here that have probably never built a sail that know far more than a sail maker does.......

Don't be like that. Your posts are really interesting. Thanks for sharing, particularly being an ex-professional. This thread is 100% learning experience for me.

Demon sails/ 5 Oceans? Please don't be discouraged :)

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jn1 said..

Matt UK said..
I'm not even going to bother on this site any more, theres far more people on here that have probably never built a sail that know far more than a sail maker does.......

Don't be like that. Your posts are really interesting. Thanks for sharing, particularly being an ex-professional. This thread is 100% learning experience for me.

Yeah , and I'm drinking gin.
.

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Matt UK said..
I'm not even going to bother on this site any more, theres far more people on here that have probably never built a sail that know far more than a sail maker does.......

Well I'm sorry you feel that way, and my own sails have won many regattas and a world championship - although that was a long time ago now, and in dinghies. I made my first sail when I was 16 years old. I did then work in the windsurf sail industry for a while and was also the test editor for Windsurf magazine.
There are of course several ways to make a sail and to achieve the shape required, and in windsurfing the key is to get the relationship right between the sail cut and the mast bend.

On topic, the 'lift' created by a sail is complex, and it's definitely an armchair discussion about how a sail can 'hold the board's nose down'. I always worry that this sort of language is simply out of date stuff we inherited from the longboarders.
My own feeling is that we windsurfers control the board trim with our sailing stance, which is a function of mast foot position and footstrap positions. Boom height and fins are further tuning options.

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Doggerland said..

jn1 said..

Matt UK said..
I'm not even going to bother on this site any more, theres far more people on here that have probably never built a sail that know far more than a sail maker does.......

Don't be like that. Your posts are really interesting. Thanks for sharing, particularly being an ex-professional. This thread is 100% learning experience for me.

Demon sails/ 5 Oceans? Please don't be discouraged :)

I was just thinking, why don't we leave the answers to sailmakers?

Good example is Point-7 AC-X (2020). to AC-0 (2024). Same weight, same number of battens, zero cams. The AC-X works great but the AC-0 feels significantly more stable and locked down ... obviously due to a change in shape/panels/battens but ... how exactly?

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duzzi said..

Doggerland said..

jn1 said..

Matt UK said..
I'm not even going to bother on this site any more, theres far more people on here that have probably never built a sail that know far more than a sail maker does.......

Don't be like that. Your posts are really interesting. Thanks for sharing, particularly being an ex-professional. This thread is 100% learning experience for me.

Demon sails/ 5 Oceans? Please don't be discouraged :)

I was just thinking, why don't we leave the answers to sailmakers?

Good example is Point-7 AC-X (2020). to AC-0 (2024). Same weight, same number of battens, zero cams. The AC-X works great but the AC-0 feels significantly more stable and locked down ... obviously due to a change in shape/panels/battens but ... how exactly?

That usually means they got the sail working with the mast bend better - with the leech opening efficiently to release power.

Have had sail makers of major brands tell me one sail has more downward pressure and another sail more lift.

Part of the reasoning was where the draft was.

I always think of the Olympic Laser Dinghy when it comes to tight leech sails. The Laser sailor sets the board trim with his weight, by moving forwards or backwards, but he also works the board physically with the sail settings he has. There's no question that the sailor is 'holding the nose down' - where that is appropriate, in their case to reduce drag.
As with windsurf sails, the tuning options for this Laser rig are very limited. The Laser was designed in 1969 and has been updated very little in the decades since, being a one design class.

I write a lot about sail design, and I can certainly sound like an armchair windbag when doing so. Ironically, that's right on topic here.

The first picture here shows the Laser sail set baggy with a tight leech, and the only way to flatten the sail is to add kicking strap tension or to crank the mainsheet in hard when sailing upwind (see picture two). Both those tuning devices flatten the sail by bending the mast and that mast bend in turn releases some of the leech at the head of the sail. It's still quite hard to get a Laser sail to twist off much. But of course it is an old-fashioned sail design.

These dinghies don't use downhaul as we windsurfers understand it, but they instead have a sail cloth with stretches at the luff panel, being tensioned in line with the cloth 'bias'. So if you flatten the sail with mast bend you can also tension the 'Cunningham hole' to tighten the luff panel cloth, and that, with the Laser rig, brings the fullness of the sail further forwards again. The fullness or extra shape in the front of the sail is what gives forward drive. Without the Cunningham hole tension the flattened Laser sail would be more sideways pulling, and that would not work for the upwind sailing that dinghy course racers do.

Our windsurf sails at first copied these antiquated dinghy sail ideas, especially in the early Dacron cloth 'Windsurfer' days, when longboard sails were triangular and had only short battens at the leech - just like the Laser dinghy here.

The rig development in windsurfing took a different path with fully battened sails, and the technological leaps that happened later included 1) Using downhaul to bend the mast (which in turn flattens sail shape), 2) Using that same downhaul to release the upper leach at the sail head, in conjunction with seam placement and luff panel shaping, 3) And of course, for racers, we also use twin luff panels with camber inducers to create a structured/engineered aerofoil sail - and one that is far more sophisticated than the laser sailors use.

It is then in that historical context why we can talk very differently about sail cloth that does not stretch under downhaul load, and why full length battens are angled the way they are. We use luff round and broad-seaming to establish the shape of the sail, and modern sail cloths bring rig stability as never before.
The modern windsurf sail is no longer a windbag used to drift around a lake until it gets too windy.
(And the true windbags, myself included, are now locked up on windsurf forums like these. )

The people who aren't windbags are the sailors who are legends in this class, like Robert Scheidt, Ben Ainslie, Paul Goodison, Tom Slingsby, and so on. It's worth remembering that these guys weren't held back by the deficiencies in their antiquated rig.
But hopefully, we can still accept armchair, theoretical, and opinionated sailing for what it is.

PS. This is just for fun - and for when the wind doesn't blow. Plus you might learn something.

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Basher said..

duzzi said..

Doggerland said..

jn1 said..

Matt UK said..
I'm not even going to bother on this site any more, theres far more people on here that have probably never built a sail that know far more than a sail maker does.......

Don't be like that. Your posts are really interesting. Thanks for sharing, particularly being an ex-professional. This thread is 100% learning experience for me.

Demon sails/ 5 Oceans? Please don't be discouraged :)

I was just thinking, why don't we leave the answers to sailmakers?

Good example is Point-7 AC-X (2020). to AC-0 (2024). Same weight, same number of battens, zero cams. The AC-X works great but the AC-0 feels significantly more stable and locked down ... obviously due to a change in shape/panels/battens but ... how exactly?

That usually means they got the sail working with the mast bend better - with the leech opening efficiently to release power.

I am trying to bring back this thread to the original question ... what changed quite dramatically in the Ac-0 vs AC-x is the leading edge and front of the sail resulting in much more pinned down, stable sailing. Similar behavior of a twin cam Ac-2. Right there, in those changes, might be some of the answers to "how do some sails press down a board"

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duzzi said..

Basher said..

duzzi said..

Doggerland said..

jn1 said..

Matt UK said..
I'm not even going to bother on this site any more, theres far more people on here that have probably never built a sail that know far more than a sail maker does.......

Don't be like that. Your posts are really interesting. Thanks for sharing, particularly being an ex-professional. This thread is 100% learning experience for me.

Demon sails/ 5 Oceans? Please don't be discouraged :)

I was just thinking, why don't we leave the answers to sailmakers?

Good example is Point-7 AC-X (2020). to AC-0 (2024). Same weight, same number of battens, zero cams. The AC-X works great but the AC-0 feels significantly more stable and locked down ... obviously due to a change in shape/panels/battens but ... how exactly?

That usually means they got the sail working with the mast bend better - with the leech opening efficiently to release power.

I am trying to bring back this thread to the original question ... what changed quite dramatically in the Ac-0 vs AC-x is the leading edge and front of the sail

resulting in much more pinned down, stable sailing. Similar behavior of a twin cam Ac-2. Right there, in those changes, might be some of the answers to "how do some sails press down a board"

I just watched that video promotion and was left none-the-wiser here. Point Seven make great sails but this guy is just giving the sales spin about buying the cheaper rotational sail version instead of the better and faster cam'd sail with full carbon mast and booms. I imagine there's quite a price difference.
For sure, rotational sails are easier to gybe and to water start. For sure, if you are a racer then you want the stability of a cam'd sail, used with 100% carbon masts and booms, and that's what gives you better wind range and better overall racing performance. .
If you've used both sails and prefer one or the other, then fine.

Not sure how this relates to the discussion here. Hopefully both designs work, now that they are properly developed.

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Basher said..





I always think of the Olympic Laser Dinghy when it comes to tight leech sails. The Laser sailor sets the board trim with his weight, by moving forwards or backwards, but he also works the board physically with the sail settings he has. There's no question that the sailor is 'holding the nose down' - where that is appropriate, in their case to reduce drag.
As with windsurf sails, the tuning options for this Laser rig are very limited. The Laser was designed in 1969 and has been updated very little in the decades since, being a one design class.

I write a lot about sail design, and I can certainly sound like an armchair windbag when doing so. Ironically, that's right on topic here.

The first picture here shows the Laser sail set baggy with a tight leech, and the only way to flatten the sail is to add kicking strap tension or to crank the mainsheet in hard when sailing upwind (see picture two). Both those tuning devices flatten the sail by bending the mast and that mast bend in turn releases some of the leech at the head of the sail. It's still quite hard to get a Laser sail to twist off much. But of course it is an old-fashioned sail design.

These dinghies don't use downhaul as we windsurfers understand it, but they instead have a sail cloth with stretches at the luff panel, being tensioned in line with the cloth 'bias'. So if you flatten the sail with mast bend you can also tension the 'Cunningham hole' to tighten the luff panel cloth, and that, with the Laser rig, brings the fullness of the sail further forwards again. The fullness or extra shape in the front of the sail is what gives forward drive. Without the Cunningham hole tension the flattened Laser sail would be more sideways pulling, and that would not work for the upwind sailing that dinghy course racers do.

Our windsurf sails at first copied these antiquated dinghy sail ideas, especially in the early Dacron cloth 'Windsurfer' days, when longboard sails were triangular and had only short battens at the leech - just like the Laser dinghy here.

The rig development in windsurfing took a different path with fully battened sails, and the technological leaps that happened later included 1) Using downhaul to bend the mast (which in turn flattens sail shape), 2) Using that same downhaul to release the upper leach at the sail head, in conjunction with seam placement and luff panel shaping, 3) And of course, for racers, we also use twin luff panels with camber inducers to create a structured/engineered aerofoil sail - and one that is far more sophisticated than the laser sailors use.

It is then in that historical context why we can talk very differently about sail cloth that does not stretch under downhaul load, and why full length battens are angled the way they are. We use luff round and broad-seaming to establish the shape of the sail, and modern sail cloths bring rig stability as never before.
The modern windsurf sail is no longer awindbag used to drift around a lake until it gets to o windy.
(And the true windbags, myself included, are now locked up on windsurf forums like these. )

The people who aren't windbags are the sailors who are legends in this class, like Robert Scheidt, Ben Ainslie, Paul Goodison, Tom Slingsby, and so on. It's worth remembering that these guys weren't held back by the deficiencies in their antiquated rig.
But hopefully, we can still accept armchair, theoretical, and opinionated sailing for what it is.

PS. This is just for fun - and for when the wind doesn't blow. Plus you might learn something.

1- We can twist off the Laser rig as much as we want - it's just that extreme twist is very, very slow. We can put 90 degrees twist if we choose. In other dinghies (ie Tasar) and cats we can do the same thing and the wingmast and full battens will prefer the flapping a Laaer sail may create - but again we don't normally do it because it's dog slow.

It's not that dinghy designers and sailors are fools who don't understand twist - most top dinghy sailors adjust twist more often than most windsurfers. It's just that a non-foiling dinghy tends to have much higher hull drag than a windsurfer and therefore reducing aero drag is crtical. As world-famous aerodynamacist Dr Mark Drela (designer of world champ and America's Cup wings and foils) says, the lift/drag of the rig is, in itself, irrelevant - what is important is the lift/drag ratio of the entire vessel.

A low-drag board must therefore have a low-drag rig in its normal operating regime, and because it's not normally sailing upwind in 6 knots it can compromise on the power it produces to reduce drag. A Laser is often sailing in 6 knots or less and it has more hull drag so it needs to maximise rig power and if the rig is draggier it's not very relevant.

Another factor is that a dinghy can depower by adjusting the angle of attack more than a board, so it does not NEED to rely on twist as much. That is not a defect of the dinghy rig, it's a factor that different craft have different requirements and strengths.


2 - The current Laser sails DO use cunningham pretty much as a windsurfer does. The 6 is now using so much cunno that in one race alone they tore out something like 27 mast tips after a spar spec change. Under max cunno the load is probably similar to a Raceboard sail and the twist is not much less. The radial 7 relies dramatically on cunningham and the whole leach inverts. This is not an armchair opinion but the experience of someone who can still win races at nationals.


3- The Laser sail is not a "a windbag used to drift around a lake until it gets too windy." The class wind range is covers about 18 knots and the modern windsurfer sail has a dramatically smaller range than a Laser sail. If you took your board up against the typical Laser fleet, much of the time you wouldn't finish a lap before they were starting the next race. To get that range and light wind power it needs a different design.

There have been classes that adopted the full-batten flex-tip composite rig, like the Byte CII, and they have not gone much faster and the class is essentially dead. So why be so destructive as to insult a class that gets more people on the water than any other?


4 - Dinghies and shortboards are different and it's no that one rig is inferior. - they just have different purposes Shortboards are fantastic in a breeze but not at close racing, light winds, fluky winds, etc etc. Implying that a shortboard rig is better because it works well in a much narrower wind band (in strength and direction) is as silly as saying that this bike is crap;


because this bike can go faster in some situations;


They are different sorts of sporting equipment different situations. There is nothing wrong with a piece of sporting kit that optimises some aspects (durability, range, simplicity, etc) in a different way to another piece. They are different, not worse or better.

(By the way, formerly comfortably in the 20 in slalom worlds and top 10 in Lasers nationally overall, plus multiple national wins against Olympians in other classes, so this is not an armchair opinion).

I'm wondering if Duzzi meant to post this P7 video (published in the last 24 hours), not the 'AC-0 and its rig components' video.
It compares the AC-0 and the AC-F (their freeride no cam sail).
I'm partly through watching it, but I think when he mentioned more luff curve on the AC-0 he forgot to say that needs a lot more downhaul which provides the stability.

?si=KbW0MD-jlaCHFuJ5

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Basher said..
this guy

Andrea Cucci, owner of P7, ex-PWA sailor (I think he entered one of the Super-x events last year) and sail designer/tester.

Chris 349 seems to think I was insulting dinghy sailors or their rigs when - as an ex dinghy world champion myself - I certainly wasn't. My post about the Laser rig was simply to show how different sails work, but still with the aim of trimming the board, depowering the sail, and generating efficient drive from what sail area you have. My use of the term 'windbag' was obviously a joke, but hopefully most can see how that term applies to any sail set without panel tension.
Dinghy sailors and yachties obviously invented sail twist before we did, and they tried to bring it under control with the kicking strap. Most dinghies also use adjustable stays and rams to bend their masts, as sail tuning devices
They also tried to stabilise their sails with extra battens, especially before non-stretch sail cloths were invented. Sail twist is also used in a different way, not least because dinghies race downwind and often at slow speeds, creating different apparent wind issues to ours.
It is however news to me that Cunningham hole tensioner is now used to bend the mast - rather than just to stretch the sail cloth. But then I haven't been to a Laser regatta for a while.

Armchair sailing can be quite fun, but in my dad's day you needed a beard and a pipe, and perhaps a pub, to be allowed to take part.

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PhilUK said..

Basher said..
this guy

Andrea Cucci, owner of P7, ex-PWA sailor (I think he entered one of the Super-x events last year) and sail designer/tester.

Andrea Cucchi (not Cucci). Yes, the point is that the Point-7 Ac-x to Ac-O (note: they are both cam-less) evolved in the direction of more race-sail-like-stability and more "press down" (following the original post nomenclature). The changes that make that happen, and the trade-offs associated with them, are obviously well understood by Andrea, and some of those reasons are hinted out in the video.

It would be nice to hear more, maybe Point-7 will blog an even more technical video, instead of going off in the usual side s#@t-storm about dinghy sails or bicycles

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duzzi said..
Andrea Cucchi (not Cucci). Yes, the point is that the Point-7 Ac-x to Ac-O (note: they are both cam-less) evolved in the direction of more race-sail-like-stability and more "press down" (following the original post nomenclature). The changes that make that happen, and the trade-offs associated with them, are obviously well understood by Andrea, and some of those reasons are hinted out in the video.

It would be nice to hear more, maybe Point-7 will blog an even more technical video, instead of going off in the usual side s#@t-storm about dinghy sails or bicycles

'h' is silent in Italian, I just made it invisible
Not once did he mention "press down" "pin the nose" or whatever way you want to call it.
On other forums in the UK there has always been the question of "Can I use my no cam freeride on a slalom board", and a typical response by some was "No it wont work so well, because it wont pin the nose like a slalom sail". Some posters kept repeating this, including a local here (Mikerb). Another local here, Amanda, used her Sailworks Retro 6.6 no cam on a 99l Fanatic Falcon with no issues. She can gybe better than most here. Maybe top speed/average speed was down a bit from a slalom sail, but she wasnt slow. Same for Mark on his P7 no cam 5.8/7m. Mike knew Amanda & Mark, so it was all a bit odd. If you watch slalom sail tuning videos they say more downhaul to loosen the leech to make the board fly off the fin more (but dont over do it). Not enough downhaul will make the board sticky (maybe push down on the nose more if you want to call it that). So I dont get this idea of slalom sails pushing down on the board to make them work.

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PhilUK said..

duzzi said..
Andrea Cucchi (not Cucci). Yes, the point is that the Point-7 Ac-x to Ac-O (note: they are both cam-less) evolved in the direction of more race-sail-like-stability and more "press down" (following the original post nomenclature). The changes that make that happen, and the trade-offs associated with them, are obviously well understood by Andrea, and some of those reasons are hinted out in the video.

It would be nice to hear more, maybe Point-7 will blog an even more technical video, instead of going off in the usual side s#@t-storm about dinghy sails or bicycles

'h' is silent in Italian, I just made it invisible
Not once did he mention "press down" "pin the nose" or whatever way you want to call it.
On other forums in the UK there has always been the question of "Can I use my no cam freeride on a slalom board", and a typical response by some was "No it wont work so well, because it wont pin the nose like a slalom sail". Some posters kept repeating this, including a local here (Mikerb). Another local here, Amanda, used her Sailworks Retro 6.6 no cam on a 99l Fanatic Falcon with no issues. She can gybe better than most here. Maybe top speed/average speed was down a bit from a slalom sail, but she wasnt slow. Same for Mark on his P7 no cam 5.8/7m. Mike knew Amanda & Mark, so it was all a bit odd. If you watch slalom sail tuning videos they say more downhaul to loosen the leech to make the board fly off the fin more (but dont over do it). Not enough downhaul will make the board sticky (maybe push down on the nose more if you want to call it that). So I dont get this idea of slalom sails pushing down on the board to make them work.

I had no intention to start a discussion cam vs no cam, or downhaul or sail tuning. The point was that the net result of the changes AC-X to AC-0 is that with the AC-0, besides the rock solid stability, a board (my AV 88SL 88 in this case) seems to be much more pinned down, e.g. in chop there is much less of the slight bouncing up/down. And so because both sails are cam-less, and therefore there is no complicating factor, it is the difference in their shape and panel disposition that should hold some clue about the original question by Paducah: "How do some sails press down on the board". Again, maybe Andrea Cucchi ("chi", roughly, is pronounced like a "k" in Italian ) will have a blog post about that in the future.

Isn't it the component of wind deflected parallel to water surface drives board forward, if some is also deflected downwards or upwards it will push sail up or down. Since the sailor is hanging off the boom any change in the up/down component will be experienced in more of less of their weight pressing down through their feet and mast foot. I guess sail makers try to maximise deflection of wind parallel to water, but nothing is perfect and small differences in the up/down component we interpret as pressing board down..
By the way, my mast foot tendons develop a bulge rather then thin with use wave sailing, interpreted as mast foot pressure rather than lift.

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patronus said..
By the way, my mast foot tendons develop a bulge rather then thin with use wave sailing, interpreted as mast foot pressure rather than lift.

That could be bumps or landings. And.. wave riding is riding on top of the board apposed to hanging off the side and back.

I'm also a ex sailmaker/designer.
i can only assume you ment battern alignment in as far as that's where you usually put the shape, it's not the battern alignment that affecting the shape it's just letting you put shape somewhere else if that makes sense.
of course and radial sails then battern alignment would make no difference.

Great video. Very informative and detailed (lower profile as it is related to forward pull and stability is around 6')

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duzzi said..

Great video. Very informative and detailed

(lower profile as it is related to forward pull and stability is around 6')

I found that video told me very little, but it is a good sales pitch promotional video for that brand of sail.

1) The basic for all sails is that the designer tries to give the sail a good wind range, and that in turn is about the sail panels and luff curve working with the mast bend. This is true for all brands.

2) Any modern windsurf sail uses the tension of the luff panel in conjunction with the mast bending under downhaul load to create a stable forward section for the sail. With the front of our sail or 'foil' made stable we can then have flatter sections in the leech to 'exhaust' the sail, and the upper leech on any windsurf sail is set loose so that the head of the sail can twist.

3) Batten numbers and batten stiffness are used to support the designed sail shape, but can't really change the seamed shape of the sail. We do need battens to support flat panels and to prevent puckering or sail flutter, and the bigger the sail, the more battens you generally need.

4) We use seam shaping to add fullness to the front panels, and the more shape you have in the front of the foil, the more a sail is forward-pulling. The opposite would be a sail where all the belly is in the middle of the panels, which would be more sideways pulling.

5) On topic, the higher up you add fullness to the luff panels the higher up will be the pull of that sail. A tighter leech also makes the sail pull from higher up. Both those aspects would in theory mean that when accelerating there would be a greater downward force on the board. Most race sails are made more for top end speed rather than early planing acceleration, and so the fullness is often cut low down in the luff panels, in theory then reducing downward pressure on the nose of the board.

6) So in summary, the way in which a sail is said to 'hold down the board nose' relates to the drive point of that sail and how high up the sail that drive point is. We often want a tight leech and high drive point for early planing and acceleration, but a lower drive point for top speed and for control.
7) With any rig, you can alter what you feel with different downhaul and outhaul settings and with the chosen mast position in the track.
8) With all the above points explaining windsurf sail design, I still believe that it becomes meaningless to say a sail 'holds the nose down' . The power of a windsurf rig is transferred to the board via the sailor and the mast foot, and it's the chosen stance which then determines board trim. Thinking about your body positioning on the board and your stance in relation to the rig is then a much better way of understanding how to drive your board efficiently. The term 'holding the nose down' then becomes a redundant.

9) We have people of different ability levels reading this. So, on a basic level, if you are sinking the tail and the nose is riding high, then shift the mast foot backwards in the track to get the mast more upright, and that will allow you to lean forwards more. You might also try shifting the front foot straps forwards.

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Basher said..

duzzi said..

Great video. Very informative and detailed

I found that video told me very little, but it is a good sales pitch promotional video for that brand of sail.

Why don't you publish your own video describing how your windsurfing sails are built? Bashing and dismissing other people efforts really gets old after a while. Of course Andrea is talking about his sails (sorry, not yours), but there is a lot of good and detailed information in that video. I am sure that there is less if you are a sail maker, and I am sure Andrea is omitting a lot of more technical stuff.

How do some sails press down on the board? By deflecting air upwards.

Most of the deflection is sideways of course. But if overall it has a bit of up or down in it there's your answer. Hard to measure, just look at the sail and guess where the air is deflected to.

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Basher said..
So, on a basic level, if you are sinking the tail and the nose is riding high, then shift the mast foot backwards in the track to get the mast more upright, and that will allow you to lean forwards more. You might also try shifting the front foot straps forwards.

Here we disagree, yes as the mast moves upright the C.E. also moves up, this will put more downward force on the nose, but I doubt it will out way the shift of rig weight forward. Take into account rider weight as well and it gets left in the dust.

Have you ever done any speed sailing in mirror flat water as well as chop?
In mirror flat water, moving mast track back is faster, moving it forward again in chop is faster.

You just might be correct if the sailor isn't putting any weight on the harness, but i sail powered up with as much weight on the harness as possible.

certainly isn't mirror flat, but there's not a lot of chop. board is trimmed for entry to be between the feet. Mast track most of the way back.

...with all of the above points said, I guess the gear must be made from Helium... the rig must just float above the board, because gravity doesn't come into it at all.

1. Made dinghy sails that won some stuff. Top job for an amateur sailmaker.

2. Worked as a sailmaker professionally for a number of major WINDSURF sail manufacturers.


When it comes to theory of how a WINDSURF sail works in full powered conditions and I have to choose one, I think I know who ima listen to.

Newtonians have entered the chat

Thanks to both aeroegnr and bel29 who shared the following video either here or elsewhere. Patrik spends quite a bit of time talking about this very subject and from what I can gather it has a lot to do with CoE, leech twist (not only the amount but the behaviour), back handness, sail profile (e.g draft location) and batten tension (especially in upper battens). The twist part is more nuanced than just more twist vs less but how the twist happens e.g more flexible top masts vs more cc or harder top.

I don't think he's ever won a dinghy championship but he's worth a listen to all the same. (My dinghy resume consists of multiple capsizes, finishing mid-fleet and once hoisting the jib upside down.)

Starts somewhere around 21: 28

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decrepit said..

Basher said..
So, on a basic level, if you are sinking the tail and the nose is riding high, then shift the mast foot backwards in the track to get the mast more upright, and that will allow you to lean forwards more. You might also try shifting the front foot straps forwards.

Here we disagree, yes as the mast moves upright the C.E. also moves up, this will put more downward force on the nose, but I doubt it will out way the shift of rig weight forward. Take into account rider weight as well and it gets left in the dust.

Have you ever done any speed sailing in mirror flat water as well as chop?
In mirror flat water, moving mast track back is faster, moving it forward again in chop is faster.

You just might be correct if the sailor isn't putting any weight on the harness, but i sail powered up with as much weight on the harness as possible.

certainly isn't mirror flat, but there's not a lot of chop. board is trimmed for entry to be between the feet. Mast track most of the way back.

I'm glad everyone is still engaging with this - I thought you'd all got bored.
I wasn't dissing the Point Seven video, and please watch it to the end if you can be bothered - because it says nothing about what we are talking about here.

We are still left with people talking about the dead weight of the rig being a factor in holding the nose down, when in fact the rig weight is partly neutralised when we are planing along, which is why mast foot pressure reduces once we are planing.
Gravity still exists however and it's then the remaining rig weight and the sailor weight acting downwards - acting against the hydrodynamic lift from the hull and the fin. You then trim the board by shifting your body weight forwards, and that's what best stops you ploughing along (slowly) with the board nose stuck in the air.

The point about moving the mast back in the track is it stops you from being trapped under a raked mast, in the old school lavatory position. And a more upright stance in turn allows you to lean forwards more with your body weight, with the added benefits of freedom to physically drive the board through chop.
You should also be able to use a smaller fin with this better stance, adding further to board speed.
Plus the upright rig is more efficient in driving the board forwards.

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Paducah said..
Thanks to both aeroegnr and bel29 who shared the following video either here or elsewhere. Patrik spends quite a bit of time talking about this very subject and from what I can gather it has a lot to do with CoE, leech twist (not only the amount but the behaviour), back handness, sail profile (e.g draft location) and batten tension (especially in upper battens). The twist part is more nuanced than just more twist vs less but how the twist happens e.g more flexible top masts vs more cc or harder top.

I don't think he's ever won a dinghy championship but he's worth a listen to all the same. (My dinghy resume consists of multiple capsizes, finishing mid-fleet and once hoisting the jib upside down.)

Starts somewhere around 21: 28

I'll see if I can find time to watch that, but we are in danger of talking at cross purposes here. If you are foiling then that is fundamentally different from fin windsurfing.

A foil generates huge upward lift that means the windfoiler has a very different sailing stance from the fin windsurfer.
Foil sails, as a result, are generally more high aspect and cut with a tight leach. The race courses usually sailed by foilers are also different, often with more downwind work (as per the IQfoil class).

Even for downwind slalom, we foil in lighter wind but still at great speed, meaning the apparent wind angles we set our sails to are totally different. On a broad reach in light wind you stay fully sheeted in on a foil board, so there is less need for sail twist. That's a massive discussion in itself.