Moth on Foils: 35.9 knots(41.29 mph)

[sigurd]

PhilSweet, can you please explain more about what the dithering is, or does, in this instance?

Is it possible that the rapid change of lift starts vortices, increasing drag?

Is it likely that the max and min flap deflection experienced when the flap skitters rapidly, is more outside the profile drag bucket than the average of these?

Since induced drag is proportional to lift squared, is it true that, for the same average lift, an alternating lift coefficient has to have a higher induced drag than if the lift is constant?

If so, lowpass filtering between wand and flap should decrease drag.
I picture a wand connected to the flap actuator via a rubber band. The flap actuator is also connected to the ground (boat) via a dampener, for instance a hydraulic cylinder with a constricted fluid passage between each side of the piston - same as a bike suspension. The point would be to let the wand follow the surface, whereas the flap would not react to the smallest waves. Another way could be to add mass to the flap actuator. This would lower the bandwidth of the system, and possibly create cyclic loops as mentioned? Also the actuation force seems very low, so a delicate enough hydraulic cylinder might be difficult to find? Those "pneumatic muscles" comes to mind again - no stiction, low mass.

 

[Doug Lord]

Moth on Foils!

From Sail-World.com:

"From photographer Thierry Martinez a photo of First Moth Wing built at Object 2 Skiff Works in Toronto for Bora Gulari (USA), 2009 Moth World Champion.

The wing have been designed by Magnus Clark(CAN) and Steve Killing (CAN), Magnus was crew for Fred Eaton’s C Class winner of 2010 C Class world Championship.

Rossi Milev (CAN) and Rob Paterson (CAN) from Object2 Skiff Works built the wing in one week with Bora Gulari (USA) and George Peet (USA). "

ThMartinez/Sea&Co website: http://www.thmartinez.com

http://www.sail-world.com/USA/New-Moth-Wing-image---Built-for-Bora-Gulari-in-Canada/75709

http://forums.sailinganarchy.com/index.php?showtopic=114387&pid=3022956&st=0&#entry3022956 ( difficult to listen to audio interview with Gulari here -zero technical info- post#31)


left photo by Thierry Martinez at the above site(click on image) -right photo from SA-probably also Thierry Martinez :

 

[Doug Lord]

Moth on Foils!----possible new top speed

It may be confirmed that Nathan Outeridge has set the new Moth Class top speed at 31.1 knots! Checking to confirm....

 

[Doug Lord]

Moth on Foils-----New Wing

From Magnus Clarke on SA regarding Gulari's new wing:

Big credit to Steve Killing on this project. I don't think it's been said enough.

Steve is instrumental in making this all happen.

Good job to all the boys for pulling the project together so quickly.

MC
I cut it twice and it's still too short

 

[Doug Lord]

Moth on Foils--AMAC on The Wing: kill it if it wins?

Interesting comments from AMAC-Andrew MacDougall(designer of the MachII and KA Sails) from Mach II forum:

Adam May did an amazing job to build a wing and get it working straight up mainly by himself. Bora has another on the go, being built by the Canadian C Cat team. The initial questions are: Is it faster? Will it hold together? Will it be faster around a racecourse? If these questions answered in the affirmative, then more important questions are: Does it enhance the experience sailing a Moth? Will it make a class that has become the darling of the sailing world in a very short time, over technology itself so that it suffers the same malaise of the C class Cat , very small numbers and only sailed at major events? My gut feeling is if the class lets the rig become the standard then the answer to the last question could well be true.

My firm belief is that we need to restrict the rig to make the boat stay as a super practical, easily transportable, fun to sail dinghy.

But, I hear you say, what if we had done this, like many wanted, when foils were introduced? There is a serious difference between the introduction of foils and the wing and the biggest one is that foils enhanced the experience of Moth sailing to a degree that has changed not only the perception of the Moth but also of sailing around the world. Recently I found a pile of old sailing magazines; there was one from 1987, it had a picture of a C Class Cat with a wing rig not looking so different to the ones they have today. The introduction of the wing sail to the C Class did not enhance the class to the point where people were jumping into it because it was such a cool thing to do, and a will not for the Moth either.

So the biggest question to me is the one that I don't yet have a really good answer to: If the class decides to restrict the wing, how do we do it with a simple and elegant rule like the one that was used to ban windsurfing style rigs. (There is a point: that is something the class restricted, and obviously gained from by not being sucked into being just another windsurfer style which could have easily happened.)

I have some ideas for a rule, but I can't yet find one that is really elegant. Most will be controversial so I won't mention them yet.

The rule should be such that it does not restrict development, that makes sense for the class, but it should restrict development that makes the class too much more expensive (I know there are arguments that the wing is not expensive, but unless you have very skilled free time on your hands I think you'll find it will be), fragile and difficult to transport.

And we can't gloss over the fact that the wing rig will also make the boat very difficult to rescue.

Sure I would love to build one, but my focus has always been on doing development that enhances the experience of Moth sailing and brings it to as many people as possible. The wing for me does not do that.

Am I anti wing? Hell no, I'm hanging out to pore over Bora’s when he comes to Melbourne this summer. (Then send them out on a big south-westerly on Port Phillip Bay and see how it copes )

Should it be banned now? Certainly not. The philosophy of the Moth class should stay as before; everything is allowed until it threatens the stability or functionality of class. Hopefully someone will build one that will win some races so we can really see how much better it is. Then, we act.

 

[ancient kayaker]

"My firm belief is that we need to restrict the rig ..."

- sounds like the thin end of the wedge. What does a development class mean if some developments are restricted and others are not? If we keep going along that track then we can end up with an all-wood lapstrake moth with cotton sails ...

 

[Doug Lord]

"My firm belief is that we need to restrict the rig ..."

- sounds like the thin end of the wedge. What does a development class mean if some developments are restricted and others are not? If we keep going along that track then we can end up with an all-wood lapstrake moth with cotton sails ...

========
To say I was surprised by AMAC's words is an understatement. I followed the original foil debate on the old Moth forum and this is how the "anti's" started out. I sincerely hope that the fact that AMAC owns KA sails and supplies most Moth sails is not a factor.....

 

[CutOnce]

========
To say I was surprised by AMAC's words is an understatement. I followed the original foil debate on the old Moth forum and this is how the "anti's" started out. I sincerely hope that the fact that AMAC owns KA sails and supplies most Moth sails is not a factor.....

I'm not surprised at all. More than just KA Sails, MacDougall is behind the Mach II, and if there is any hope of making money there it depends on keeping the sales volume climbing and the non-recurring engineering & tooling costs from increasing. Ratcheting the cost of a Mach II up another 2-4 thousand dollars to get a competitive boat with a wing would certainly have a negative effect on volume.

I actually agree with his position - as the wing adds a fragility factor, problematic capsize recovery, rigging complexity, shipping & storage issues on TOP of the added cost.

Once the class starts down this path, all the momentum built up since Bladerider broke the ice with production foilers dies. Everyone with a foiler has to buy-in, and this isn't the same situation as it was back in pre-foiling days. Before foiling the Moth class was a very small group of competitors at the top end, and adding foils was not a huge financial burden to the class - as the group was small. Now the amount of people with foilers is much larger and the economic requirement of allowing wings is much, much more of an issue.

I don't think it is the end of the world if the Moth class votes down wings - both the class and the wings will both survive happily without each other.

Let the Wingnuts start a new class optimized for the wing's performance.

--
CutOnce

 

[Doug Lord]

Moth on Foils!----The Wing

I'm not at all convinced that the wing will beat the highly refined "soft" sails the Moths use. Ben Halls experience with his wing in the A Class was not a show stopper. As a development class the Moth would probably be better off to let the development proceed even if the wing is fast.
See the comments by Adam May a few pages back. As to being robust I think this picture is worth a thousand words:


Adam May wingwalking-click on image:

 

[ancient kayaker]

I ... the wing adds a fragility factor, problematic capsize recovery, rigging complexity, shipping & storage issues on TOP of the added cost .... CutOnce

- but the foils have already added a fragility factor, problematic launching, construction complexity, shipping & storage issues on TOP of the added cost ...

... I'm not at all convinced that the wing will beat the highly refined "soft" sails the Moths use. ...

- let the best development win in a development class, I say.

 

[Doug Lord]

Moth on Foils!------The Wing

I agree ,Terry. Heres Steve Clark on SA:


Posted Today---

Rossi, Paterson, Bora etc.
Nicewing.
Tools, time & technique all show up in the end.
I only have the pieces of a foiling moth that Dave started and hasn't gotten around to finishing.
Frankly, while all of it is pretty straight forward, buying the mast and sail were going to be the biggest cost items, and the ones that were going to gag us.
On the other hand we can and do build wings ourselves and it will cost us less to do so.
I recognize that we are not AMAC's the usual Moth customer.

Things change. 10 years ago we were always told that C Cats were too big and expensive. Now we are told that a 72 foot wing sail catamaran is the "cheap" option.

The Moth class has developed the first truly practical sailing hydrofoil. Perhaps they are uniquely positioned to do the same thing for the wing sail.

Keep the faith!SHC

Beatings will continue until morale improves.

 

[CutOnce]

As to being robust I think this picture is worth a thousand words:

Adam May wingwalking-click on image:

I place far less worth on one picture than you I'm sure. Steve Clark or Oliver Moore might have a little to say about wing fragility (having broken Cogito's and one of Alpha's this year) Now make the wing a requirement to be competitive, and add a whole bunch of newbies to foiling into the mix. Have these newbies paying $25K US to get into the game, and then have their first crash take out a $3K wing. They aren't going to get Mach II to replace their wing for free because the person who crashed saw a picture of Adam May walking on a wing.

Guys like Adam May, Bora Gulari, Arnaud P. or Simon Payne have a pretty good chance of successfully working with a wing - because they already know how to stay upright in a wide range of conditions. Moth races are won often by the person who swims the least, not by the person who achieved the highest measured speed or best tactical decisions. These same folks are also more likely to have sponsors and not only do they get better deals on equipment, they need crash parts less. The poor guys at the back of the pack aren't sponsored, pay full retail price and in addition crash a lot more.

I know many people here like to "help" advance their pet obsessions with new technologies, but each situation has to be assessed for the potential that it may kill the class of boat contemplating the technology.

As for performance potential, I'm pretty certain a properly designed wing has the potential to out-perform even the most advanced soft sails - especially in a boat that is pretty weight tolerant like the Moth. The last America's Cup demonstrated this pretty conclusively.

--
CutOnce

 

[Doug Lord]

Moth on Foils---The Wing

Adam May:

Many people have asked about how practical it is – well it is obviously not as practical as a standard rig, but this one fits on my current road trailer, and I plan to make the top section above the hounds come off after the Euros, and then it will pack into a box about the size of our current Moth travel boxes, so that then isn’t too bad.

Cost? – I had the initial mould costs, but if you forget that, the wing probably cost me only a little more than going out and getting a new mast, boom and sail together. Having done one – the time to build another would be a lot less. Interestingly a home builder could buy the component bits and get a rig for cheaper than currently.

=====================
More Adam May:

It has been a busy time in the World of wings. The 34th America's Cup will now be raced with wing sailed cats - making the Moth the perfect feeder class!

It has been a bit of a hectic period recently, but I managing to get my boat back off Katherine for a few minutes on Sunday and went out crash testing the wing! Before I do a few mods I've got planned, I thought I'd to take the opportunity to really learn about the weak spots in a structure like this, and find out what bits need reinforcing, and which bits are fine. I'd start with some basic capsizes, and work my way up to some bigger moves! The skin is coming off, and some ribs being replaced anyway so I might as well learn about the survivability beforehand.


The initial test was to let Katherine have a go.... It survived that, so I had to work a bit harder. (See her blog http://www.foilingboatadventures.blogspot.com/ for the more colourful (pink) version of events soon)


I capsized, and stayed there for 5 minutes to see how much water would get inside. Hardly any was the result. More in the trailing element actually, and that should be sealed, so my control line entry points obviously worked okay on the front.


The C Class guys actually punch holes in the skin to drain the water out when they capsize as otherwise the water rushing down inside the wing can take out numerous ribs on its way down! Fortunately a well sealed wing laying flat in the water prevented the need for this, and stage one was passed.


Whilst capsized, I did the walk to the transom and flipped the boat over the transom. This is a nice way to load up the leach element! Five of those and still no cracking noises!


Okay time for a little party trick.. I thought early on that with a fully sealed leading edge structure, I'd have a nice buoyancy tank in the rig! Actually the volume of it would probably hold my weight quite well, and it was pretty bulletproof...

[picture of Adam standing on wing here]


Not a typical load case, but a good example of the fact that these structures can be made quite tough!

It survived that fine, so with the wind picking up a bit, I tried for some pitchpoles! Of course this is quite hard to do when you actually want to do it! But I managed one eventually, and although it made a good splat noise as the leading edge hit at pace, all was fine, and we came away from that one unscathed.

So back to the workshop for a few mods, although I think pondering over 44m versions will be taking up a fair bit of my time soon.

Oh well exciting times.

 

[ancient kayaker]

... make the wing a requirement to be competitive, and add a whole bunch of newbies to foiling into the mix ... Moth races are won often by the person who swims the least ... CutOnce

Agree with most of what you say, but for a newbie, the challenge of a wingsail won’t be any worse than learning to foil.

... I'm pretty certain a properly designed wing has the potential to out-perform even the most advanced soft sails ... CutOnce

From what I have read wings beat sails in some situations and are beaten by them in other situations. It may well be that the top people will have to bring both to suit whatever weather and conditions Race Day brings with it, to remain competitive. The poor relatives that can only bring a sail will still be able to compete some of the time, although chances are their hulls and other rig technologies will not be up to the job. Development classes like Moths and the AC are meant to be evolutionary and therefore they tend to be Darwinian.

... Many people have asked about how practical it is – well it is obviously not as practical as a standard rig ...

There is the problem of reefing, although I doubt any foiler does that in practice. I don’t fancy transporting a wing, doesn’t mean to say I not prepared to try one, though ... but then I may be certifiable. As the wing professional houses start up and become too good for amateurs to compete the cost factor will be serious, particularly as wings are likely to lack durability. That applies to sail as well, but at least they usually last for several races.

 

[CutOnce]

Mr. Haines:

My point was not about the challenge of learning to sail with the wing sail. By all reports, actually sailing a well designed wing is easier than a soft sail of similar performance intent. My point was that crashing violently will get very expensive - especially while traversing the "newbie" gulf.

Conceding weight up front, I can't see how a soft sail of the same area, using even the most aerodynamic rotating mast with controllable over-rotation would be effectively better than a current technology wing sail - all things being equal. I can concede performance may approach or arrive at the same level, but I can't see how it could be better. I guess the real gray area lies in defining the difference between a wing mast with slotted soft sail after section (which is probably a wing sail) and a soft sail on a conventional bolt rope mast.

Reefing becomes less of an issue with unstayed rigs where the wing can be feathered completely regardless of direction of travel. Adding stays changes things a lot.

Getting back on track however, there is a world of difference between Steve Clark's lab, Adam May's shop and the average person considering a Moth. Yes, people with equipment, serious experience and materials on hand can build wings at very cost effective prices - but the Non-Recurring Engineering (NRE) costs to get in the game are significant if you are talking about building carbon tubes off mandrills, vacuum bagging prepreg carbon and mold making. Ovens, autoclaves and environmental controls are not inexpensive.

I'm not going to continue to discuss these issues where out-of-context quotes are used to support doubtfully constructed arguments. Wings are expensive. 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.

--
CutOnce