Dinghy Foiling

[BobBill]

For those who pooh-poohed the notion some dinghies won't lift, unless driven like a 14, see here: http://foilingboatadventures.blogspo...ing-oppie.html

[Cheesy]

Doug beat you to it

Almost Foiling Optimist Pram! Really....

[bistros]

Originally Posted by Cheesy

Doug beat you to it

Almost Foiling Optimist Pram! Really....

Don't you mean "sosoomii"?

[Doug Lord]

BobBill-it is a terrific thing that Katherine Knight did in foiling an Opti with its own sail-no more area! But the fact is almost any boat can be made to foil in heavy air down wind. The trick comes in to make it foil upwind as well-or foil in most conditions or use the foils beneficially as intrinsic parts of a design.
"Foil assist"- where the boat only foils downwind(in as light a wind as possible) is a very viable design goal if you can either retract the foils upwind or develop enough lift to reduce drag enough for them to pay for themselves.
I guess what I'm trying to say is that there is a lot more to the use of hydrofoils on sailboats than the splashy upwind foiling machines in the pix below. And it is a largely unexplored area of dinghy and sailboat design-wide open for innovation and brilliant ideas. Of all the dinghies sailing only one-the I-14- uses foils exclusively for "foil assist" and not for full flying up and downwind speed foiling.
It's an exciting area of design just waiting to be exploited by a few brilliant,innovative designers.

[BobBill]

I agree, Doug.

I just figure that you can foil a dinghy, even a big old Lightning or Raven, if foils are sufficient to give the boat a bit of lift , not fly, but get speed from reduced drag, particularly on a beat.

I was going to foil my little Kite, until I thought better of it from a practical point of view and got more or less talked out of it, but you never know...

Heck, maybe it all goes down the drain with diminishing returns, but worth the thought and the try. After all, the Opie was going with Moth wings...

[bistros]

Originally Posted by BobBill

I agree, Doug.

I just figure that you can foil a dinghy, even a big old Lightning or Raven, if foils are sufficient to give the boat a bit of lift , not fly, but get speed from reduced drag, particularly on a beat.

I was going to foil my little Kite, until I thought better of it from a practical point of view and got more or less talked out of it, but you never know...

Heck, maybe it all goes down the drain with diminishing returns, but worth the thought and the try. After all, the Opie was going with Moth wings...

Bob:

Just adding a "little" lift doesn't cut it - the NET reduced drag has to be lower for the foils to be a benefit. Foils lifting can reduce the hull's wetted surface area, but they add a lot of surface area (of the foils themselves). Along with the surface drag of the foils, there is the form drag induced by the foils.

Basically, if the foils don't lift a serious amount of the hull out of the water, the added drag of the foil renders the exercise pointless. I really do not see much value in "foil-assist" unless the NET result of adding the foils is a benefit around the whole course - upwind & down. Being a little faster downwind has to be balanced with not being slower upwind as well. You pay the drag penalty on all points fo sail - and only get the benefit off the wind.

You can make a barnyard pig fly, given sufficient thrust and an upward vector, but that doesn't mean it can fly easily or well. Getting the Opti to foil is interesting in an offbeat kind of way, but it isn't going to re-energize the foiling revolution. More of a curiosity and "Ripley's Believe it or Not" item than a design revolution.

--
Bill

[BobBill]

Bill, yes, I agree...why I wrote "if foils are sufficient." Understated.

I am with ya, but the point does remain that in some way foiling can offer something.

It is fun messing around anyway, isn't it?

It is odd it took so long for it to catch up with sailing...

Honestly, if I could foil the Kite turbo without too much trouble, I would. Am sure just a wee foil on the rudder would provide some lift, but it would also require stronger rudder and create inconveniences I wish to avoid, at least at this point. Have to get her moving efficiently first.

Now I must remove some snow after the plows finish. (14 inches...bah-humbug.)

[Doug Lord]

BobBill, if you want to make your boat foil in the same basic way and for the same reason Katherine did the Opti, go for it! It will be fun!
If you do it like she did the limitations don't matter.....
--------------
Just for the heck of it I looked up the weight of an Optimist=77lb-not much more than a Moth(66lb.). SA= 35sq.ft. So strong wind, downwind, up she comes!

[Chris Ostlind]

In some ways, this so totally reminds me of the guys who put 20" $1K a piece, bling wheels and $600 a piece nasty tires on a Nissan Sentra, just because they wanted to know if they could.

Lookin' oh-so dope from the outside and when you haul your ass into the thing... it's still a crappy, burned-out plastic Sentra.

Nice plan.

Next-up... a foiling Star, Yingling, H12 1/2, J-boats... the whole world is mine, I tell you... MINE!!!!!!

[BobBill]

Chris, Funny.

You got it right.

Yes, the wheels should never cost more than the vehicle.

No, I will never get a Kite to fly, and I likely will never foil the rudder or dagger, but why not think about it?

The wheel metaphor works - foils should never cost more than the boat...

[Munter]

Good on them for trying it out. While it doesn't prove that foils will work in all applications it does give some creedence to the suggestion that there are more applications for foils than just moths.

I think the light weight of the opti is probably key in getting lift off. The moth foil transplant probably wouldn't work as well in heavy boats like finns etc.

[Doug Lord]

You could make almost any current dinghy under 20' foil with the right size foils in strong wind downwind. The foil size(area) is the only requirement that has to be met for this very narrow "for the hell of it" approach. Practical foiling/foil assist etc is another matter entirely....
Any way you look at it, the practical application of foils to dinghies and keelboats is in its infancy with a huge potential for application of the technology. "For the hell of it" approaches like the Optifoiler serve to bring that home to more and more people. I think it is fantastic!

[bistros]

Originally Posted by Doug Lord

You could make almost any current dinghy under 20' foil with the right size foils in strong wind downwind. The foil size(area) is the only requirement that has to be met for this very narrow "for the hell of it" approach. Practical foiling/foil assist etc is another matter entirely....
Any way you look at it, the practical application of foils to dinghies and keelboats is in its infancy with a huge potential for application of the technology. "For the hell of it" approaches like the Optifoiler serve to bring that home to more and more people. I think it is fantastic!

Great post Doug, rational and cogent right up to the "keelboat" point.

Can't say that I think a foiling Opti (and the like) is the carnival freakshow that will help foiling gain credibility in the eyes of the masses though. Luca Devoti has done a great textbook-quality job demonstrating how to introduce a new one-design boat with his D-One. His plan from the beginning was to elicit feedback from credible experts, incorporate that feedback to create a solid product and then proactively drive the product to success at internationally-attended regattas. His objective from the get-go was fun and stress-free class racing, not just selling the first couple of boats.

Although foiling is mildly interesting to me, it does not seem to have the appeal to the general public necessary to make it a revolutionary change in sailing. People sail for many reasons, and foremost amongst them is the quiet, low stress recreational activity that brings fun and enjoyment in kind of a retro/environmentally sound package. High stress, high risk, noisy edge-of-the-cliff excitement can be found in many forms - and foiling sailboats aren't on the radar of most excitement junkies. By adding hydrofoils, high speed, high skill requirements and dangerous crashes to sailing you are taking it out of the low-key recreational category that attracts most people.

--
Bill

[Doug Lord]

"Dangerous crashes" are NOT intrinsic to the hydrofoil experience. Such crashes may or may not occur during development depending on the sophistication of the original design iteration. Development class boats may have a higher incidence of such crashes due to their sometimes experimental nature.
The skill required to successfully foil is dependent on the sohistication of the original design and development more than any special requirement due to the "nature" of hydrofoils. A lot of the assumptions made about sailing hydrofoils are based on the rather public development issues of the Moth class rather than any analysis of a fully developed sailing foiler-there is a big difference.

[BobBill]

By inference in the two posts above...did not the AC boats add keels for lift as well as tracking?

Water, like air, is very conducive to lift foils, it is curious it took so long to get popular.

Just an observation.