Moth on Foils: 35.9 knots(41.29 mph)

[Doug Lord]

Moth on Foils!----The Wing

Mr. Haines:

Wings are fragile, witness Team USA's $4-500,000 worth of C Class breakage this year on two days sailing. Wings are stunning performers.*

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CutOnce

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As an anonoymous participant here your are free to say whatever you want to with no fear of being held accountable.
If you read what Steve Clark has said or particularly what Adam May has said(and done)-both very experienced with wings-you would realize that, at best,
your analysis of the wings for the Moth is flawed. It really wouldn't take you very long to read the material.....
Posts: 1134(May standing on immersed wing, 1136(Steve Clark) and last but not least 1138(Adam May on transport, cost and ruggedness).

* Not in the A Class and not known for sure in the Moth class(so far)

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From Tom Speer:

The differences between rigid wingsails and wingmast/sail combinations are mostly in the things you have ruled out.

The slotted flap of a rigid wingsail allows it to achieve a higher sectional lift coefficient than most soft sails. However, soft sails could do better if they could achieve a particular shape, especially if that shape wasn't constrained by having to be a membrane tension structure. The maximum lift has been important in the C-class catamarans, because their area limit makes it hard for them to be fully powered up on the runs.

The control system of a rigid wing allows the wing to be taller without experiencing excessive loads due to leech tension. I believe this was the main advantage of the wing on USA 17 over its soft rig. The control system also makes it possible to control the shape, such as twist and camber, in a more extensive and precise way than for a soft sail. There's no reason why a similar control system couldn't be developed for a soft sail.

There's no reason for the wing to use the same fabric as the soft sail, because the loads are taken by the ribs and spar instead of the fabric itself. Plus, there are two sides to a wing, so that would double the amount of fabric used. If the wing has the same fabric as the sail, it will be much heavier - and far heavier than it needs to be. The wing on USA 17 weighed the same as the mast, boom, mainsail and jib of the soft sail rig. So it was heavier when a headsail was added to the wingsail, but comparable in weight when sailing wing alone.

If the boat is limited by its heeling moment, then the soft sail and rigid wingsail will be trimmed to produce the same lift. USA 17 went to the wing in order to produce that heeling moment in lighter wind.

There's nothing magical about a rigid wingsail. The soft sail rig on USA 17 was faster than the wingsail in some conditions. Whether a wing or soft rig will be faster depends on the class constraints and the sailing conditions.

 

[Doug Lord]

Moth on Foils!---The Wing

This is from Fred Eaton-owner of the company that built the latest Moth wing- on SA:

Congratulations, Bora, on the launch of your Moth wing.

To answer people's questions about O2 building Moth wings for other customers:

Bora's wing is very exciting, but I think it's important to spend some time to make sure that we're all happy with how things work before we run off building lots of these things. Among other things, we need to know if it is fast, and if it holds together. I think that through the upcoming world's O2 will be interested in learning with and from Bora about how wings work out on Moths. We could not ask for a better partner to work with to learn about the application of wings on Moths.

Assuming the experiment is a success, and the class is interested, then Object 2 will consider building wings or wing kits for Moths. We think kits are a good way to go because we believe Mothies are generally pretty handy people and home assembly could potentially reduce the cost of the finished wing by a significant amount.
Fredo

 

[CutOnce]

Mr. Haines:

Mr. Lord has helped clarify my position quite well. Although his obvious intent is to provoke a conflict yet again, he has actually proven my point.

Reading through Mr. Speer's material brings to focus the point of the Moth class' interest in wing sails: Higher lift and less drag can be achieved with a wing sail at a given fixed sail area. One of the long standing critiques of the Moth class has been that the limited sail area has also limited performance potential, especially in light and marginal conditions. Exactly the same issue put forth on the C Class.

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[ancient kayaker]

... Mr. Speer's material brings to focus the point of the Moth class' interest in wing sails: Higher lift and less drag can be achieved with a wing sail at a given fixed sail area ..

A rigid (one-piece) wingsail has lower drag than a fabric sail but it doesn’t have as much lift; I was interested in trying out such a wing some time ago and ran into that problem in the analysis stage. The Gulari wingsail shown in Doug’s post # 1127 is a two-piece slotted wing which looks like those on high-speed land yachts. It will have more lift and the ability to operate at a higher angle of incidence than simple rigid wing. I gave up on my project when I realized the need for such a wing because of its additional complexity.

Whether the slotted wing can beat a good fabric sail at similar lift depends on the conditions. Wing sails come into their own at high speeds as the apparent wind moves forward; the angle of attack becomes less for similar lift and then low drag becomes crucial. At some point a fabric sail will lose control over its shape; Tom Speer suggests this problem is soluble, but I don’t see how.

Is the Moth fast enough to reach these conditions? If the sail area is the limiting factor, then I don't believe the wingsail will deliver the extra lift to achieve a speed breakthrough. If sail control is the limiting factor there is more hope IMHO.

This thread seems like an interesting discussion of various technical aspects so far. The high-dollar enterprises such as the AC and l’H together with development classes such as the Moth are moving our sport and passion forward at a great pace; most of it is not for me but it’s great to watch from the sidelines.

 

[CutOnce]

A rigid (one-piece) wingsail has lower drag than a fabric sail but it doesn’t have as much lift; I was interested in trying out such a wing some time ago and ran into that problem in the analysis stage. The Gulari wingsail shown in Doug’s post # 1127 is a two-piece slotted wing which looks like those on high-speed land yachts. It will have more lift and the ability to operate at a higher angle of incidence than simple rigid wing. I gave up on my project when I realized the need for such a wing because of its additional complexity.

Whether the slotted wing can beat a good fabric sail at similar lift depends on the conditions. Wing sails come into their own at high speeds as the apparent wind moves forward; the angle of attack becomes less for similar lift and then low drag becomes crucial. At some point a fabric sail will lose control over its shape; Tom Speer suggests this problem is soluble, but I don’t see how.

Is the Moth fast enough to reach these conditions? If the sail area is the limiting factor, then I don't believe the wingsail will deliver the extra lift to achieve a speed breakthrough. If sail control is the limiting factor there is more hope IMHO.

This thread seems like an interesting discussion of various technical aspects so far. The high-dollar enterprises such as the AC and l’H together with development classes such as the Moth are moving our sport and passion forward at a great pace; most of it is not for me but it’s great to watch from the sidelines.

Given that much of the Moth's sailing is in apparent wind mode (when foiling) I believe the wing sail will be a benefit - and the lower parasitic drag may allow foiling at a lower transition speed, and also potentially incrementally higher top end speeds. At 30 knots, drag is the biggest factor holding the system back speed wise (given that foil drag is optimized already).

I agree completely regarding the high lift of soft sails, but it is at the expense of drag, and can only be effective at lower speeds. As soon as you flatten a soft sail enough to deal with the high speeds and laminar flow in apparent wind sailing, the lift drops off as well.

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[Doug Lord]

Moth on Foils!----The Wing

1) The Gulari wingsail shown in Doug’s post # 1127 is a two-piece slotted wing which looks like those on high-speed land yachts.
2) Is the Moth fast enough to reach these conditions? .

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1) Terry, in his radio interview on SA Gulari refused to rule out that the wing
was a three element wing with an integral(but small) flap on the back end of the forward element.
2) The Moth top-end speed is higher than that ever recorded for a C Class Cat if I understood Steve Clark correctly. Also, during the prep for the LAC Paul Larsen and the UK team went up against a Moth and said the Moth was faster upwind while the C Class was slightly faster off the wind. No top guns on either boat.
The Moth has beaten a fleet of A Class cats over 6 years ago and a couple of F18's about four years ago as well as pacing a Tornado. Of course, the boat is a dog off the foils(if it has foils)

 

[ancient kayaker]

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1) Terry, in his radio interview on SA Gulari refused to rule out that the wing
was a three element wing with an integral(but small) flap on the back end of the forward element.

I can see what might be a provision for adjusting slot width. I might be wrong about the resemblance to the land yacht wing sails that I have seen: I believe the fore and aft wing elements in those are more or less simply hinged for cambering purposes rather than slotting. The Gulari wing might be more sophisticated. It wouldn't be surprising if there is more to it than he wants the eye to perceive at this point.

 

[CutOnce]

Also, during the prep for the LAC paul Larsen and team went up against a Moth and said the Moth was faster upwind while the C Class was slightly faster off the wind. No top guns on either boat.

Excuse me? Who exactly are you to be calling Paul Larsen anything but a Top Gun? Perhaps I've missed your name in the record books.

Paul is the project lead and pilot on the Vestas Sailrocket project, and a far more accomplished sailor from any perspective you wish to measure than anyone here has claimed to be.

Perhaps you would like to rephrase this offensive nonsense and give credit where due.

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[Doug Lord]

Excuse me? Who exactly are you to be calling Paul Larsen anything but a Top Gun? Perhaps I've missed your name in the record books.

Paul is the project lead and pilot on the Vestas Sailrocket project, and a far more accomplished sailor from any perspective you wish to measure than anyone here has claimed to be.

Perhaps you would like to rephrase this offensive nonsense and give credit where due.

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"Once": as far as I remember Paul Larsen was not on the boat the night they raced the Moth. But even if he was he is not a "Top Gun" in the C Class- as you would know if you had paid attention to the racing this summer. He is ,however, someone I admire and respect a lot!

 

[Doug Lord]

Close up of the Killing/Clarke wing for Bora-it is 3 element. Look at the frames for the first element and then look closely at the frames closest to the trailing edge of the first element(2nd element?).

click on image and then again on resulting image:
(both from SA)

 

[CutOnce]

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"Once": as far as I remember Paul Larsen was not on the boat the night they raced the Moth. But even if he was he is not a "Top Gun" in the C Class- as you would know if you had paid attention to the racing this summer. He is ,however, someone I admire and respect a lot!

Mr. Lord:

I did see Paul Larsen take a visibly slower boat and sail it so well he passed Canada 3 (Orion) at times as well as Patient Lady IV (FRA) in Newport. There were flashes of brilliance visible even though the equipment was obviously not up to par.

We differ on our definition of racing - mine involves a set race course with marks, Notice of Race, a race committee and rules of racing. Yours apparently is two boats sailing within eyesight of each other.

To each his own however. I'll look again to find your name in the record books as you feel qualified to comment on people with far more demonstrated ability than I give you credit for.

Best wishes,

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[Doug Lord]

Moth on Foils!----HCW 2010 race

Speaking of Moth speed this is from Sail-World regarding the "Heaven Can Wait" 2010 race held just recently:

Lake Macquarie sailor Nathan Outteridge, became the King of the Lake smashing the Heaven Can Wait race One Lap Dash record for the 29 nautical mile race around the lake this afternoon.

He flew across the finishing line off the Royal Motor Yacht Club Toronto, recording two hours seven minute and 31 seconds, leading the Moth fleet and well ahead of the first 18 footer, Andrew Chapman’s Fisher & Paykel and the leading multihull, Clive Kennedy’s Egan 9.5 metre catamaran Two Tribes.
As he began derigging his Moth Outteridge commented 'It was a great race. I had a poor start compared to Tom (Slingsby) and Scott (Babbage) but managed to get through Tom early as he did not have good speed.

'I have lived on Lake Macquarie all my life and I just did not realise how big it is. I capsized eleven times in all, a few times at over 20 knots, but nothing broke and I managed to sail really fast.

'My top speed was 26.5 knots, I got a good puff out of Belmont Bay and broke away.'


pix--Nathan Outteridge-by Nicole Scott:

(click on image and then again on resulting image)

 

[Doug Lord]

Moth on Foils!-----comparision

See the new AC fact sheet here for the 72' wing sailed cats: http://www.boatdesign.net/forums/multihulls/34th-americas-cup-multihulls-34612-2.html#post408870

Note that the projected top speed is 32 knots. See the title of this thread for the current Moth Class top speed(which will shortly go up) and let it sink in that there really is a revolution in sailboat design going on. The Moth has equalled or beaten every sailboat from a C Class Cat on down and is projected to be almost as fast as a new 72' AC catamaran. That is just flat amazing!

 

[Doug Lord]

Moth on Foils!

Moth wing discussion here: (post 32 and Moth site)

http://www.boatdesign.net/forums/multihulls/understanding-wing-technology-34697-3.html#post410134
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Weymouth Speed week-Moth second fastest boat-after Thomas Jundts 26' monofoiler! http://www.boatdesign.net/forums/sailboats/mirabaud-lx-2010-a-33020.html

 

[Doug Lord]

Moth on Foils!-- mothcast

Here is Bruce's(Technologica) Mothcast featuring Adam May discussing his wing:
http://www.mothcast.net/