Windfoil Sails.

Foiling related talk in here
ronnie
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Windfoil Sails.

Post by ronnie » Sun Jan 06, 2019 11:40 am

The only sail I bought with windfoiling in mind is a Gaastra IQ 5.4m.
GaastraIQ5.4msmall.jpg
GaastraIQ5.4msmall.jpg (202.58 KiB) Viewed 375 times
I rig it with a 3/4 batten and slacken the downhaul and outhaul for more low end power, but the sail was designed for higher winds, and is designed to work with more tension in the material. That was my first rigging of it in the picture. I find there is a limit to how much a light wind can push the sail into shape to produce more power, so I tend to set it as a compromise of bottom end power, keeping the battens rotating, stability of the centre of effort, and wind range.
I set the boom a bit lower, as I tend to foil closer to the sail and use shorter harness lines - and it helps waterstarting in a lighter wind. It also tends to put more pressure on the front foot, which is a factor when flying.

I use my 4.5m Gaastra Poison with a 370 mast. That seems to work well with the foil, as when set with low downhaul, the softer mast twists off when needed, but gives good low end power.
My Severne S1 6.3 seems to have a luff tube with elastic properties, so it is a bit better at taking less downhaul and softening the tension in the sail, so that seems to help a bit.

Because I am choosing sails based on what is the bottom end for waterstarting, the range of wind for selecting from 6.3m to 5.4 or 4.5m is small (10knots to 15knots?). Selection is also dependent on how variable and gusty the wind is. I use the 5.4 the most. I always fit the uphaul, but waterstart if possible.

It is maybe an example of a hybrid sail - in the same way that a slalom board can be fitted with a reinforced deep tuttle box and then used with a foil.
So it is a compromise.

The SUPfoil type of sails - such as the Naish Lift, seem to be designed to be pushed into a powerful shape by a light wind and be pumpable and luffable.
Last edited by ronnie on Sat Jul 06, 2019 5:19 pm, edited 3 times in total.

Sailrepair
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Re: Windfoil Sails.

Post by Sailrepair » Mon Jan 07, 2019 11:05 am

Semi soft sails often have that vertical crease up the luff from the batten tips. On some sails the crease requires quite a lot of wind pressure to take it out and until the crease is out they are not very efficient. I would try rigging your sail with less downhaul and more outhaul to reduce the luff tension.

They key factor is how much wind is required to push the sail body into shape. Softer battens help in this regard as does less skin tension which normally comes from reduced luff curve.

Most of my foiling is done with bigger sails and I have used everything from 3 batten wave sails to full on race sails and my preference is for single or twin cam sails as they hold their draft through the holes in the wind. Fuller sails also tend to be less twitchy and let you concentrate on your flying. too many cams though can make the sail too stiff and you only get a limited number of attempts to rotate the sail while still flying round a gybe.

ronnie
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Re: Windfoil Sails.

Post by ronnie » Mon Jan 07, 2019 3:50 pm

Sailrepair wrote:
Mon Jan 07, 2019 11:05 am
Semi soft sails often have that vertical crease up the luff from the batten tips. On some sails the crease requires quite a lot of wind pressure to take it out and until the crease is out they are not very efficient. I would try rigging your sail with less downhaul and more outhaul to reduce the luff tension.

They key factor is how much wind is required to push the sail body into shape. Softer battens help in this regard as does less skin tension which normally comes from reduced luff curve.

Most of my foiling is done with bigger sails and I have used everything from 3 batten wave sails to full on race sails and my preference is for single or twin cam sails as they hold their draft through the holes in the wind. Fuller sails also tend to be less twitchy and let you concentrate on your flying. too many cams though can make the sail too stiff and you only get a limited number of attempts to rotate the sail while still flying round a gybe.
BIB
Thanks for the advice Sailrepair.

That is what I found was needed, and it does give the best compromise for foiling.

I'll see if I can rig the 5.4 with a 370 top on a 4m base. The masts are stiff top, so it might reduce the tension in the sail.

EDIT: This is the IQ with the 370 top on the 4m mast base. The 2 halves join together fine.
This is the sail set with 4cm less downhaul, and 2cm less outhaul than recommended. It is easier to push into a full shape than with the 4m mast. I reckon it gains 2cm less downhaul and 1cm less outhaul in comparison to the 4m mast. I was using 26cm of extension.
IQ370400mastssmall.jpg
IQ370400mastssmall.jpg (153.26 KiB) Viewed 376 times
I think I only get a restricted amount of advantage from using the IQ. I have a 5.3m Gaastra Manic, and that makes getting an extra sail not particularly good value (even at OFFER price). If I was bridging between a 5m Manic and the 6.3 S1, it would have been better value for money.
EDIT: Using the 370 mast top may make a worthwhile improvement in the bottom end power and maybe handling too - but I haven't foiled with it yet to check that.
July 2019. I finally got to use the 5.4m sail in very marginal wind. The wind was stronger when I was rigging, so it was rarely enough to waterstart, but the sail worked well and seemed to be powerful and stable in the light wind.

The Naish Lift sail was designed for what I am looking for, but mast compatability, price and a long boom length requirement were reasons I didn't go for the Lift. (194 is at the top end of my boom range)
This review of the Naish Lift by Casey Treichler seems to mitigate some of the worries I had.
https://reefwarriors.wordpress.com/2018 ... il-review/
Last edited by ronnie on Sat Jul 06, 2019 5:19 pm, edited 1 time in total.

ronnie
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Re: Windfoil Sails.

Post by ronnie » Mon Apr 29, 2019 4:07 pm

2018 5.9m GA IQ set with 3/4 batten on a Gaastra stiff top 4m mast from pre 2017.
On the sail bag, it recommends a 430 mast, but on the website it says 4m or 430. This will be my new largest sail.
I only tried it with the 4m as I wanted to remove tension from the sail for lighter winds, and the only other option I would have tried was a 370 top on a 430 base, but they don't fit together. Quite happy with the result with the 4m.

EDIT: Aug 2019.
I have rigged the 5.9 with a 370 mast top & 400 base with 42cm of extension. -4cm on downhaul & -2cm on outhaul. Hoping the boom location is not an issue, as about 30 years ago, I had a mast snap because the boom was below the reinforced area. It is easier to push the sail into a full shape. I have now used the hybrid mast with 42cm extension and so far so good.

EDIT September: I have switched to the full batten because I need the sail to work with the 105 Foil board for windsurfing and an 88L Stubby, which both need the pull to be stable and close to the mast. I'll use the 4mbase370top for up to 14 knots wind (for windfoiling only) and the 4m mast above that.
M42B32T370.JPG
With 4m mast and 2cm less outhaul & 1cm more downhaul than recommended.
M32B304m.JPG
Last edited by ronnie on Fri Sep 13, 2019 8:26 pm, edited 12 times in total.

deckchair
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Re: Windfoil Sails.

Post by deckchair » Tue Apr 30, 2019 6:47 am

nice idea using different mast tops and bottoms to change the performance of the windsurf sail but it is still a compromise as you say. with the smaller sizes (5M and below) you have plenty of wind to form the sail shape but getting it stable is problematic because you have no downhaul. Then the bigger sizes you need shape for low end power but then when foiling less shape . i think in the future we will see much shorter masts ,longer booms , cams' and adjustable outhauls.
how is your foil sail coming along sailrepair ?

ronnie
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Re: Windfoil Sails.

Post by ronnie » Tue Apr 30, 2019 6:57 am

deckchair wrote:
Tue Apr 30, 2019 6:47 am
nice idea using different mast tops and bottoms to change the performance of the windsurf sail but it is still a compromise as you say. with the smaller sizes (5M and below) you have plenty of wind to form the sail shape but getting it stable is problematic because you have no downhaul. Then the bigger sizes you need shape for low end power but then when foiling less shape . i think in the future we will see much shorter masts ,longer booms , cams' and adjustable outhauls.
how is your foil sail coming along sailrepair
I agree - the 4.5m Poison I use - I use with a 370 mast, but rig it much the same as for windsurfing. It produces a lot of power for it's size, but handles gusts very well. For foiling, I use it from when I can waterstart it comfortably and it is stable when turning the power up and down, but I don't foil in winds much above 20 knots.
I'm buying the IQ's because I can get them at well discounted prices and I want to use my existing masts - which are Gaastra stiff top. Foil sail masts seem to be constant curve.

On the 2013 6.3m SI, with low downhaul the centre of effort does move more, but it seems to have a semi-elastic material in the luff tube? because it shortens more than normal when off a mast and the rest of the sail goes into a series of waves. That seems to make it cope a bit better with less downhaul.

I tried the 5.4m on the 4m mast with low downhaul and it handled badly - very unstable, so it did need to be close to the windsurf settings to work well.
Last edited by ronnie on Fri Aug 09, 2019 10:33 pm, edited 1 time in total.

Sailrepair
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Re: Windfoil Sails.

Post by Sailrepair » Tue Apr 30, 2019 7:24 am

deckchair wrote:
Tue Apr 30, 2019 6:47 am
how is your foil sail coming along sailrepair ?
I have just about finished the main sail body, I just need to make the batten pocket ends and then I can start on the sleeve.

I was wondering if it is time for those optional camber inducers of the 80's to reappear. then you could have your standard freewave type sail for bump and jump or pop its camber inducer on and have a more effective foil sail. I found such a cam in my garage the other day. Gaastra even had cams that you could switch on and off while sailing along.

ronnie
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Re: Windfoil Sails.

Post by ronnie » Tue Apr 30, 2019 7:42 am

I'm keeping an eye on wing sails, which will be available soon and seem to have some advantages for tacking and gybing. They also have disadvantages compared to a sail. This one has an inflatable leading edge and a boom. Alan Cadiz is the rider (well known windsurfer from way back)


This one floats, but is not adapted yet for use on water. It has a carbon spar&boom and aluminium battens. A water version would probably have carbon battens and be a wing version of a windsurf sail (they develop their wings with some co-operation with Ezzy Sails). i would expect it to be more efficient than a wing with an inflatable leading edge. She is a beginner at wing sailing, but a good surf foiler.


I have a SUP/foil combination that could suit a wing sail.
Last edited by ronnie on Tue Apr 30, 2019 7:53 am, edited 2 times in total.

deckchair
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Re: Windfoil Sails.

Post by deckchair » Tue Apr 30, 2019 7:45 am

cam inducers that you pop on or off great idea .I can feel 3d printers up and down the country warming up as we speak :D

Jamesblonde
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Re: Windfoil Sails.

Post by Jamesblonde » Tue Apr 30, 2019 9:43 am

Early suggestions that one of these could be £800. They are using kite tech and basi g it on a 4m kite costs this much hence the price.
I'm not quite sure what I make of it yet except that for my 20mins behind a mates jet ski on my foil compared to this looks like tricky goes to ridiculously tricky. :shock:

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