Wing Sails

[tspeer]

Originally Posted by CatBuilder

Where can one find a manually controlled wing sail? I may yet look into fitting one.

All the C-class, all the landyacht & iceboat sails are manually controlled. This one had a tail that controlled the wing to a given angle of attack. It was quite easy to sail along with arms folded, just steering with the pedals and letting the wing trim itself.

The Harborwing sail is electronically controlled because the boat is intended to be autonomous. However, it would be trivial to adapt it for manual control, as the tails do all the work.

[Pericles]

The Omer Wing Sail has had quite a write up. It would seem that fighter pilots get to do it, any which way they can. Perhaps we shall see the Omer rig on a Gunboat 66?

http://www.giornaledellavela.com/con...&idRecord=7498

http://www.ibinews.com/auto/newsdesk...161344syb.html

http://www.sailangle.com/news/details/id/3143

http://www.newswinch.com/6-equipemen...oile-aile-3764

http://www.bymnews.com/news/newsDetails.php?id=67016

[Pericles]

You don't to speak Swedish to understand this article, but it helps.

The illustrations demonstrate why Wally are so interested in further development of this rig. The Soft Wing is sailing upwind, as the boat moves downwind. It's counter intuitive.

http://www.hamnen.se/Nyheter/WOW-Har-kommer-WOW

Regards,

Perry

[Alex.A]

Wally cat....

[CT 249]

Last time Ilan posted here, he said that he hoped to do some trialling against a sistership for the first time and that he would publish the outcome here. Wonder how the trials went?

He also admitted that there was at least one problem with the polars he'd published. As far as I can see (and as I'm no expert I'd be interested in other views) the performance gain claimed by the polars are far higher than the performance claim Wally make, and also far higher than the performance gains that well-designed wingsails provide in racing craft.

The polar at http://www.omerwingsail.com/performance/ shows the claimed performance for the Omer Wingsail craft against a conventionally-rigged sistership. The claimed gains are enormous - the Omer claims to go upwind at 5.2 knots in conditions where the conventional boats polars (which some posters claim to be problematic) allow for 4 knots.

The gain in performance claimed for the Omer wingsail appears to be vastly greater that the gain that wings have proven to have in class racing. For example, in the A Class cats, the wing finished in the pack; same with the Moths. I think they showed a marginal speed advantage in 18 Squares, but even in the C Class there doesn't seem to be evidence of such an advantage.

A recent piece, describing racing the British wing-masted C Class, appeared to show that they were often outpaced by smaller soft-sail cats, which surprised the hell out of me.

This is from the Invictus site, talking about running in light winds against Tornadoes, F18s, Nacra 20 etc; "Down-wind we just got crucified by the kite boats. We had some real issues with the amount of force it took to hold the full camber in the wing. We didn’t have the system onboard which we had used to good effect in Newport and we paid the price. The wind was down around 4-5 knots and dropping. Our angles were terrible whilst the kite boats could still make a decent VMG. I know we can do much better than this so it was quite frustrating not to be able to find our ‘Mojo’. In the end the wind crapped out completely... but our race was effectively over half way along that down-wind leg."

The next day there was more wind, but still..."Once again we struggled down-wind. I was trying to sail a bit hotter down-wind with more weight to windward. My theory being that it was quite patchy and we might be able to stay hooked up with apparent wind for longer. When we were hooked up, we weren’t that far off the pace. The trouble was we were mostly not in the groove... or all over the place chasing it. The boat didn’t feel as slick down-wind as she was in Newport. We got hit by a gust whilst heading for the leeward gate and did stuff but the big bows saved us again. Whilst rounding up around the leeward mark, I heard a noise I knew meant trouble. Our new/old 2004 dagger board had snapped. We still had enough down to be effective upwind so we pushed on. We had lost about %50 of our area. It wasn’t so bad as long as we ‘footed’ off and kept boat speed. In the fresher breeze, Ol’ INVICTUS began to flex her ‘C’ class guns and do that cool upwind thing where she just goes substantially higher and faster than anything else. We would get left behind downwind... and find ourselves coming back into the top mark with the front runners.
We had great starts on the third and fourth races and gave everyone a good look at how a wing-sailed catamaran can go to weather... even with only half a dagger-board. Towards the end of the third race I began to move further to leeward down-wind and trade speed for depth. It worked a lot better and when in the groove we couldalmost... but not quite hang on to the good guys. Whenever we lost it we would get rolled by anything with a kite including the Spitfires from time to time."

So the 25 foot long wing-masted C Class (admittedly handicapped with a breakage) was rolled downwind by 16 foot Spitfires at times. Given that the C Class probably suits wings beautifully and the C Class wing is very sophisticated, where is the evidence of a speed advantage of the magnitude sometimes claimed?

It would be interested to get more info on the current performance of Cs against Formula 20s, etc, as that one article certainly wasn't conclusive. Certainly the Cs are fantastic, however evidence of a performance increase of the quantity sometimes claimed appears had to find in reality.

None of this is trying to say that wingsails don't work, of course. It's just that there's some reason to woinder whether some claims are over-enthusiastic.

[Corley]

It would be interesting to see a current C Class with a standard rig go against a hard rig C it seems on average that when the two types of rig are compared that the wing on average returns better results from 300sqft of sail.

When I watched the capsizes shown in the video on Sailing Anarchy I couldnt help but think that maybe a tri format with wider beam and lots of dihedral could help them extract more power from the rig may also address the bow burying that they suffer. OK I know I'm flogging a dead horse but I do often wonder whether an "open" C class could attract enough interest to be viable in todays internet connected world.

[ImaginaryNumber]

Boat, mast and sails built by Bertrand Fercot

[Ilan Gonen]

Originally Posted by CT 249

Last time Ilan posted here, he said that he hoped to do some trialling against a sistership for the first time and that he would publish the outcome here. Wonder how the trials went?

Yes, I did say I hoped to do the sea trial against a sister ship. Unfortunately, it has not been done yet (we were very busy building the new WOW prototype for megayachts on the same boat).

“Omer” Performance – please have a look again at the pictures of the boat’s instruments I posted at that time (see: Soft Wing Sail) and compare with the polar diagram in the web site.

The general performance comparison you made between the rigid wings of A class / C class cats and soft wing of a cruiser is not good enough. Rigid wings, with high aspect ratio and small sail area, are excellent wings for racing (very efficient aerodynamically). However, when it comes to downwind, light apparent wind and small sail area, the performance can’t be as good as in all other wind directions. Soft wing sails for cruisers that can hoist, reef and fold, are less aerodynamically efficient, therefore, designed with larger sail area that makes the difference in downwind performance.

[CT 249]

Sorry, Ilan, are you saying that the soft wingsail is actually faster than a "rigid" wingsail?

If the soft wingsail is more efficient than a rigid wingsail, why don't C Class cats etc use them?

If the soft wingsail is less efficient than a rigid wingsail, how come the soft wingsail seems to claim a bigger performance advantage over conventional sails than rigid wingsails have over conventional sails?

With all due respect, static photographs of instruments are not completely convincing proof of performance claims. There have been many similar performance claims for novel rigs that do not appear to have been backed up in reality.

[Pericles]

photographs of instruments etc.

http://www.artbible.info/art/large/10.html

[CT 249]

Pericles, surely it's fine to ask for independent proof of claims?

There are many conflicting claims for boatspeed based on instruments. For example, at

http://www.ybw.com/forums/showthread.php?p=2479688

there is someone claiming "on the Elan 37 I race we have a target upwind speed of 7.3. We regularly achieve this, but this is with laminated sails and a full crew on the rail"

At the same forum, the owner of a Bavaria 37 with shoal keel and cruising sails is claiming 6.1 knots boatspeed at about 35 apparent in 16.1 knots of true breeze.

On Sailing Anarchy someone is claiming that the Elan 37 is about as quick upwind as the J/109. See http://forums.sailinganarchy.com/ind...c=81289&st=675.

If the stock Elan 37 is as fast as a J/109 and the Quantum Sails target for a J/109 are right, then the stock Elan should be doing around 6.25 knots at 25 apparent in the conditions in the Wingsail pics, which indicates that the wing is not providing superior performance.

I am NOT saying that anyone is being misleading, however it is extremely difficult to correlate the various claims. Therefore it would be very interesting to see the results of a proper test of comparative performance.

Doubting Thomas? Not quite - I'm not doubting someone who I have been following. I'm just asking if the planned testing of the claims has been carried out.

It's not that hard to prove superior performance - just go out and race comparable boats and then show the elapsed times and some race detail. Certainly wingsails and wingmasts work very well on some craft (I've sailed on quite a few wingmasted craft and own a couple myself) but on others they have shown little if any performance benefit.

[BigCat]

Originally Posted by CatBuilder

Where can one find a manually controlled wing sail? I may yet look into fitting one.

http://bigcatcatamarans.com

Designed for cruising, not racing. There are at least four of us that post on the Yahoo Junk Rig group who have come up with very similar ideas.

[Pericles]

CT 249

It is downwind that the Omer rig scores. With the soft wing pivoted to face into the apparent wind, the aerofoil shape creates lift (a lower pressure area on its upper surface) to leeward. This lift draws the boat faster than ghosting with a standard sail of the same area. I don't think the C Class solid wings offer this facility; the ability to point aft.

As BigCat points out, the rig is for cruising boats, not racers and it's extremely unlikely that Wally Yachts would risk their reputation on a rig that does not work as described. Wally Yachts were already working on something similar and combined their research with Ilan's.

"In the course of its R&D wing sail programme, Wally teamed up with Ilan Gonen, an ex fighter pilot and enthusiastic sailor, who had also developed a similar project, Omer Wing Sail."

"The result of this collaboration is the new Wally Omer Wing Sail, the wing sail technology for cruising yachts that offers unprecedented advantages:"

http://www.sailangle.com/news/details/id/3143

Regards,

P

[Ilan Gonen]

Sorry, 249, I have never said that soft wingsail is more efficient than a rigid wing. Please read again my answer to you few days ago. I wrote there: “Soft wing sails for cruisers that can hoist, reef and fold, are less aerodynamically efficient”. Furthermore, I don’t know what rigid wing C class catamarans claim in comparison with a monohull, soft wing cruiser claims. Is there any comparison at all?

There are very many variables that play a role when you analyze the efficiency of sails and wingsails. In general, wings are more aerodynamically efficient than sails (bigger L/D ratio) and rigid wings are more efficient than soft wings (better shape).
However, this is not the only question one should ask before having one of these on his boat. The question is what the needs are. If you are a cruiser or a weekend racer, and you want to replace your rig to a more modern and more efficient one, I suggest that you go for a soft wingsail that you can hoist, reef and take down, which have bigger performance than the traditional sails, easier to handle, need a smaller crew, etc. While if the boat is for racing only, I suggest you go for a rigid wing (very efficient rig) – but you have to take into consideration that you can’t reef it, you can’t take it down (not a problem for small cats, but very problematic for larger yachts), and you have relatively small “sail area” for downwind.

Although I don’t know you personally, I have the feeling that nothing I say here will convince you. Therefore, I invite you to sail with me and experience it yourself. I plan to be on June/July in Ancona / Italy. Just let me know when you come.

[Paul B]

Originally Posted by Pericles

With the soft wing pivoted to face into the apparent wind, the aerofoil shape creates lift (a lower pressure area on its upper surface) to leeward. This lift draws the boat faster than ghosting with a standard sail of the same area. I don't think the C Class solid wings offer this facility; the ability to point aft.

If the rig points aft I don't think it is going to give much lift in a direction that drives the boat forward. Draw your vectors.

I don't see good evidence that the existing OMER rigged Elan 37 is as fast or faster than the standard sloop rig of the same boat. The number shown on the upwind point of sail look slow, and the number shown on the offwind point of sail can be easily manipulated by sailing "Esses" and snapping the photo at just the right time.

The WOW marketing fluff was written more than a year ago.
Have any boats been built using the WOW system?
Are any boats in build that will use the system?
Are any boats under contract that will use the system?

If this system or something similar does prove out to be "better" than a modern fractional rig it will be a great thing for shorthanded sailing. Even if it only approaches the performance and ease of the rigs it has to compete against (modern sloops, modern "Wylie" Catboats) it will probably get some market share.