Dinghy Foiling

Jeez, Doug!

Doesn't matter what type of boat it is - going from 20 knots to zero is a massive deceleration, especially if you are airborne and landing on water. This doesn't have anything to do with the Moth class - it has everything to do with speed on the water and stopping fast.

Sailing in my Laser 5000 twin wire skiff is fun, but there isn't many times I've finished sailing without some blood in the boat. Control lines, trap wires, racks - everything becomes an issue when you are moving fast enough to keep the boat upright and stable. The level of activity necessary in faster boats brings the potential for trouble higher.

In physics terms, higher potential energy manifests itself as kinetic energy at some point. That energy is often dissipated quickly when you stuff the bow into a wave, or you don't react fast enough to a gust or lull.

Crashes happen to everyone, whether they are sailing a Moth, a 49er, a Tornado or a Hobie. Speed is more dangerous than going slow. Foiling has nothing to do with it. You want to sail fast? you have to accept you can get hurt.

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Bill

 

Yes,it is a revolution!

Some poor guy is getting beaten up on "Dinghy Anarchy" for daring to raise the idea of foiling a Laser. Phill S and other "experts" there paid no attention to the kids(?) weight. Turns out that he plus a Laser is lighter than Bora Gulari plus a Moth-so in his case Moth foils would work perfectly! Amazing....

Here is a guy that has tried to foil a boat I don't recognize-looks like he was/is close:
NOTE:The video pictures were shot WITHOUT the rudder foil-new video should happen any day now.....
From youtube: http://www.youtube.com/watch?v=FR5rxy5rdOg
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More power to ANYBODY that experiments with foiling-best way to learn!
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Boat in video is a Starling Class Dinghy(NZ):

LOA-Max 9.58'
Beam 4'
Hull Weight 90lb
Crew 110-154lb
SA ? guesstimate: 60-70 sq. ft.

 

You really don't see the differences in the opposing sides of that equation, do you?

Just a simple, one size fits all, set of figures and Zippity-Doodah, away we go on our foils.

 

Doug - what you see as being "beaten up", others might call "guidance to help newbie avoid wasting money". I just read the SA thread and while some posters have a stand-offish tone they are all just trying to guide somebody who has asked for advice regarding a potential project. It appears your prejudice towards foiling sailors is getting in the way of making an objective judgement.

 

Laser foiler

I read that thread and I think even a couple of posters there remarked on the negative tone. And the information "Phil S" gave was just dead wrong and not related to the facts at all. Thats not helpful any way you look at it.
The most important-and helpful- post was the one about the Starling showing how much fun a kid can have doing it his way. Sure he might make mistakes but so what?
The idea of trying to discourage the guy with made up "facts" or no facts at all just strikes me the wrong way. That guy(or gal) is light enough that the all up weight of the Laser plus crew is lighter than Dave Lister+Moth or Gulari+Moth. Moth foils or home made foils(like the Starling guy did) with the same area as a Moth foil would definitely work.
Give the guy a realistic assessment,not a prejudged lecture that he'd be wasting his time...

 

Fun foils

I am guessing the Starling class forbids foils, and the sailor knows it.

Still, the idea that one can use a foil to gain a bit of lift for a dinghy, even a stodgy Lightning or X boat, does offer some interesting options for anyone interested in going that far. Not to fly, mind you, but just "lighten" the load so to speak. Imagine a C boat with foiled boards enough to reduce heeled waterline 5%...gets my attention.

A Laser weighs in around 90 (hull), and I can see some dodgers taking older boats that have gone "out of round" and juicing them a bit - get enough dodgers doing it and class is born...no harm done; quite the opposite, perhaps.

I am not a big fan of the flying moths from a comfort and the esthetic sailing perspective, but I have become a fan in the uniqueness and experimental sense. I and others surely believe foiling will evolve a bit in many classes. Fun to see, it is!

I mean it was Australia II's unique AC application in '83 when keel foils were made for the same reasons. It took some time to catch on, which is a bit odd, considering the number of tinkerers in the sport.

 

I think experimenting with foils is a good way to learn about them. That said there is a lot of info on the net to help anybody that is interested figure out what it would take to foil any particular boat in terms of foil area.
Tom Speer once said that for "foil assist" to be beneficial the wetted surface of the hull involved needs to be reduced by something like 4 times the planform area of the foils. Just a rough guide.

 

Doug:

People DID give the guy realistic advice, including Phil. It isn't just rough numbers that define whether or not a boat is going to work - it is how all the components work together. Phil's concerns about foil strength are worth consideration. He know how far these things can be pushed. You can't just take weight away from the crew and add it to the hull and expect the boat to work the same. The increased sail area here requires more righting moment, and a heavier hull and lighter crew are not the best choices.

My post was guidance on how to best achieve real success with the project - I meant a solid result that could foil regularly with good potential performance. Starting with a much lighter hull, using a better rig optimized for higher speed and apparent wind sailing - learning the physics and engineering sciences necessary to optimize foil design and control systems - all these points are indisputable good advice if a quality result is desired.

You of all people should understand and support the necessity of gathering information, doing research and optimizing design. I actually made the point that the guy asking the question would benefit from following your example of research and commitment (and then actually building something).

Giving a person with a casual interest a realistic idea of the scope of a project, real world costs and time commitment isn't being negative. It is honesty and good advice.

If I recall correctly, you indicated you spent $15-20K on your aeroSKIFF foiler - optimized for foiling - with very limited success. You started with composites experience, carbon hull and tubing, a purpose designed rig etc. Could you honestly think a heavy Laser hull and rig could foil if you could not make the aeroSKIFF foil well (if at all)? Your experiences are directly relevant.

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Bill

 

Actually, nobody in that thread answered the persons question which was:
"I have wanted a Moth for about a year but I have nowhere near enough money to buy a used one. I live in California and I bought an old Laser Radial a couple years ago thats about twice as old as I am. I was wondering if it is possible to inexpensively make hydrofoils for my Laser. If I did this, how much wind would I need to start foiling (I weigh 48 kg)? "
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Phil S's comment said that the Laser with this person on board would be too heavy which is not true. A Laser is 120lb for the hull and approz 19 lb for the rig and foils=139. Now add the crew weight of 105.6 and you have a total sailing weight of 244lb. Gulari+ Moth= about 246lb-Lister+ Moth is even heav
ier. Both do "well" at those weights in competition.
So there is no question that Moth foils would lift the boat in about the same wind these two guys take off if there was enough power. Since the "person of interest" has a Laser Radial which has a 61sq.ft. "traditional" triangular main there would not be enough power at the point Gulari takes off at the earliest but the boat would foil offwind assuming it was set up properly.
If this person did the conversion for the same reason and with the same attitude as Kathleen did the Optimist he/she would probably have a blast. If he/she did it to compete with a Moth they would be disappointed. I would recommend that if this person was to go ahead that they get expert help in assessing their needs. And the fact remains that standard Moth foils would work and finding a set of older Fastacraft foils might be possible.(I have a mainfoil+daggerboard)I would consider selling or loaning!)
The total weight is what counts-the proportion that the crew is of that weight is irrelevant for structural considerations of the foils. The RS600FF is 2.5 times the weight of a Moth and foils just as well with a "normal" weight crew.
The best idea is to do it with the same rationale as the Optimist people did or to do it similarly to Will, the Starling guy: much learning could result and a whole lot of fun could be had.
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My boat foiled three different times with an extremely experimental control system-it never crashed once. I had trouble with slack in the control system and was deeply disappointed in the performance of the hull in intercoastal chop but the thing foiled.
This person could foil a Laser using Moth foils or by making foils with the same area as a Moth. He was told he couldn't do that-and that was bad information. As to whether he/she should do it or not- that depends entirely on their attitude and what they want to accomplish.
1) foil a Laser(just for the heck of it) using Moth foils? definitely possible.
2) compete with a Moth? not possible(with a Laser radial rig-or any other Laser rig)
3) foil a Laser using homemade foils of the same area as a Moth? definitely possible.
4) The major requirement for this to work is the persons 105.6lb weight and the assumption that they can sail a radial.
5) This person could go all out by adding Bill Hansens Square Head Laser sail and a trapeze but that is probably a step too far.........
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Dinghy cLasses that have foiled so far:

1) Aussie 18(surface piercing and bi-foiler)
2) 470(surface piercing)
3) Flying Dutchman( surface piercing)
4) Moth (surface piercing and bi-foiler)
5) R Class (bi-foiler)
6) Starling(bi-foiler)
7) Optimist(bi-foiler)
8) International 14 (bi-foiler)
9) 49er (bifoiler-canard)
10) windsurfers (bi-foiler & bi-foiler canard)
11) and more to come-you can bet on it...

 

Doug,

There's a certain sadness in all this with the whole, "Laser Foiling" thing.

1.) The thread in question, to which you refer, is actually over at Sailing Anarchy on the Dinghy sub-section... and not here on Boat Design.

2.) Numerous folks in the Moth and otherwise well-engaged, foiling community have told the original posting party that it is a foolish enterprise and that he'd be far better off selling said Laser and buying himself into a boat where all the hassle has been factored away a long time ago.

3.) You insist that it's; About some weirdly concocted, weight to foil surface ratio, with no regard, whatsoever, for all the vagaries of the actual hull design, the drag figures associated, the ability of the cheesy stock sail to generate enough power, etc.

In short, Douglas, you have tried, desperately, to reduce the function to a simplistic and poorly thought-out "formula" that has no bearing, whatsoever, on the realities of how a boat will behave, even if it could be brought to the point where it can "foil".

As Bill indicates, your own efforts in this regard are as iffy as a set of claims can get.. and now that heavily spun effort is long gone into the oblivion of having been ignominioously parted out. Of course, you can always complete the boat in your garage and prove to us that your guestimates are more grounded than we think... ;-) I'd really like to see that happen.

 

Oh, well. Rather than being direct and negative, I thought I would provide enough background information to enable the young lad to make his own choice about how to proceed. No one likes to be told what to do, it is more effective to give them enough information so they reach the right decision themselves.

If you want a direct opinion, I think the young man in question should get a part time job, save his money and sell his Laser when he's got enough money in the bank to buy a used (and working) foiler. For most people the challenges of making an inappropriate boat foil will prove insurmountable and frustrating. I seem to recall a member of this forum who has said he got his pride and joy to foil three times, but control issues and take-off difficulties caused him to destroy his boat suddenly and render it a pile of parts in his Mom's garage for ten years.

If getting foiling is the goal, working at a part time job and buying one is quicker than building one. That's advice you can take to the bank. If learning how to foil is the goal, the same advice is valid.

--
Bill

 

Dinghy foils

(Still off topic) Bistros, it may be all the chap has at the moment.

Getting back to the rube line here. I got to thinking, yes with a few pints, that the Laser or Laser-like hull is really not the best boat for a foil, too flimsy.

Maybe a Finn or one similar that the NZ Star dinghy...or a Phantom...something like a I-14, which we all know was too heavy but does have that big motor.

Still, we all know it is going to happen. I may lift my old Kite yet...Good on 'em all.

Can someone PM me on where can I find stuff on Hansen's square head Laser sails, etc. Got my interest and cannot seem to locate any tidbits.

 

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Big motor indeed-the 14 was the first two person bi-foiler in history-and used manual altitude control-no wand:

 

Laser rig turbo

Here's Bill Hansens square top Laser main:

His business link is(was): www.hansenaerosports.com but appears to be down...
Just found this: http://www.hansensails.com/

 

That would be a Starling