Design for DSS-Foil Assist for Keelboats

Design for DSS

I'm doing a design, as I have time, for a 12'+ "sit-in" dinghy using DSS. The foil extends three feet to the side with a 6" chord and a 63412 section. The angle of incidence of the DSS foil is adjustable-but not while sailing(so far). Upwind, at an angle of heel of 10 degrees and a "hull speed" of 4.8 knots, the RM from the foil is 25% of the total righting moment.
Downwind,at an angle of heel of 10 degrees and 7 knots, the RM from DSS can be as much as 40% of the total.
Downwind, at an angle of heel of 10 degrees and 10 knots, the RM from the foil can be as much as 58% of the total righting moment.
This design does not use a keel and is presented just to give some idea of what is possible on a very small boat.

 

Cutonce: I won't quote your post to save space but you make good points that help us all make progress. When I read your post I immediately thought of foilers which "make their own wind" as the saying goes (there still has to be SOME wind of course, I understand that) by virtue of their great speed; it seems to me that a fast moving DSS sailboat might do the same, allowing it to retain its speed upwind and hence its RM.

Surely what's sauce for the goose is sauce for the gander.

For the record I don't consider posts with countervailing opinions as damning in any way, merely helping to point the way ahead.

 

I agree with ancient kayaker, good post cutonce.

Doug, are you serious about building a little dss skiff? I think that would be just the sort of thing to start truly discovering the technology. Even a model boat would probably be better than simply relying on the youtube videos. Let's not forget that you have been championing foiling boats for at least 6 years (judging by all the posts) but despite all their potential speed pure foilers are still uncommon, probably due to cost and complication. I guess I am a little jaded by the posts on this forum about the latest "revolutionary" technology...

Lifting foils are another story though, quite common now and you have certainly been championing them for a while as well. I hope this DSS technology is in the latter camp, because it could offer a good compromise between monohull advantages and multihull advantages, esp for a cruising boat.

 

Dss

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I'm not sure yet. Welbourn tested several RC models with good results. I think it could work very well on a small ,"sit-in" type boat but getting the planing hull right for DSS is tough on a small hull. The chine has to be low enough to get the foil functional at a max angle of heel of 10 degrees or an ideal angle of heel of 5 degrees on a small planing hull.
A high performance version of a 2.4 meter surely would be an exciting boat.
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I think new development of full flying foilers has been stymied by the economy, at least in monohulls. Several new multihull foilers have been and are being developed including the Pi28, F1, Osprey and a secret project by Greg Ketterman. The R Class foiler-the first class outside the Moth to legalize foils is still active in NZ. Mirabaud the worlds largest bi-foiler continues to develop.
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By lifting foils, I presume you mean foil assist which is now very common on multihulls from beachcats on up. Still not widespread among monos except for the curved lifting foils on some Open 60's, and the rudder foils on the I-14 and National 12. DSS is the prime example of the succesful application of lifting foils to monohulls and will probably become more and more prevalent. It is the only foil system applied to monohulls, so far, that not only partially lifts the boat but also,at the same time, adds righting moment and dampens pitch and heave.

 

I was visiting my nephew, who has a degree in composites engineering, and is working for a local boatbuilder. They are building an all carbon race boat, after looking at it I was commenting on how light all the structures were, my conclusion was, since the boats designer, who has a very strong engineering background, that now days with all the computer power available that a designer knows exactly what loads are on every piece and can design just enough strength, no guesswork anymore.
I have to believe that the same power is available to predict performance. So that makes me wonder, HW seems to have a reasonable licensing fee for the DSS, it's been around for 3-4 years now, since a designer can now pretty much plug in the numbers and see if it works, given the constant drive for more performance why haven't we seen more designs incorporating DSS.
The other thing, at least for race boats, is that you have to get whatever system you race under to allow DSS and give you a rating for it. It could end up being one of those things where yes it increases the performance but the penalty you pay in your handicap is worse than the performance increase.
For me anyway I hope DSS performs as advertised, it'd be really great if it would get folks off this canting keel trend, which in my opinion anyway, is too dangerous. Though likely folks would use DSS along with a canting keel, so now your keel can fall off and you can wang something with your DSS board.

 

Under ORC DSS foil is already legal.

 

Dss

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It's also legal in the Open 60 class except they may be going one design....

 

There is a very real and direct ongoing battle in the sail boat racing world between people who wish to eliminate the spectre of endless arms races and those willing to try new technologies continually to chase five seconds on the race course. It is pretty obvious who is winning.

DSS, like canting keels, wing sails, lifting hydrofoils and most other technical advances are opposed by the majority of people owning race boats because they represent increased expense, premature obsolescence, reduced to no resale value and no fundamental increase in social enjoyment to the sport. Most people get satisfaction from racing sailboats by beating their friends around the track in a fair contest. Yes, the sensation of speed is a factor - but a much smaller factor than winning your one-design or handicap group. This is why handicap racing is such a success - and why line honours is a far less important victory.

Sailboats are already a huge recreational expense - with dockage, club membership, winter storage and normal wear and tear it sure isn't a cheap way to spend your Sunday afternoon. Very few people are willing to buy an expensive boat with new technology that makes it less appealing to the resale market than a less expensive model that already has fleet status and a stable resale value. DSS is just too much risk for most people. Risk financially, and perhaps more important social risk.

People without money concerns, without the desire for one-design fleet racing and with pure speed as their goal accept new technology easier - but even as the Open 60 crowd are finding, the expense of pure speed development machines is hard to justify in the face of smaller fleets and declining public interest. The pursuit of technology is fundamentally a game for wealthy individuals.

Racing is a social sport. The society of crew and team on a boat is critical. Competition between teams, rivalries and countries is the catalyst for the enjoyment most people get from our sport. There is no society in reaching the highest speed on the lake in a boat no one else is willing to buy.

I've been there. I built a single hand trapeze asymmetric spin skiff that is incredibly fast - but it sure would not be fair to sail it with the Contenders. And the folks in the Contender fleet aren't interested in dumping their boats to get one like mine. DSS is exactly the same thing. Although my boat is superior in every way to a Contender, Contenders have higher resale value and the instant fun of level playing field competition.

I doubt DSS will catch on beyond technology geeks like many members here. And this is not an indictment of the technology, it's benefits and what would be faster. It is the mainstream reality of the sailboat racing world. Kind of like the oxymoronic phrase "People's Foiler". Foilers are and probably always will be boats for brave individuals - the "people" have by and large rejected the concept pretty soundly. Ask Rohan Veal.

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CutOnce

 

CutOnce has it right. It's not hard to come up with ideas to make boats faster but at some point you have to ask yourself why.
At least for me anyway the most fun, frustration, best education, I had racing was usually in the slower, cheaper, classes. You weren't constantly getting wound up in the mechanics of sailing the boat, didn't feel like you could not keep up with the arms race and would get really excited if, at the end of a leg, you gained maybe a boat length on your competitor.

 

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This is simply not true if you look at all the boats being produced and sailed-especially multihulls at present.
Almost every new multihull uses curved lifting foils-it's harder to find the exception these days.
But there is more that is important: I don't believe the "majority of people owning race boats" oppose new technology-certainly not in multihulls! Not if you look at all the square top mains around. The attitude you express , I'm afraid, is not an attitude shared by the majority of people by a long shot or else there would be no innovation whatsoever.
New technology is part of the lifeblood of sailing and simply cannot be discounted.

 

Well, gentleman,
If this direction of thinking was accepted by everyone, we would be sailing doug-out canoes, or ride the logs found on the river bank up to present day.
Sure new technology is expensive/unproven/0 resale walue ... .
But at some point it either prove itself and is more or less universally accepted, or is indeed abandoned as too expensive/impractical/whatever.
As to the actual point of discussion:
*Sure, DSS is simpler and cheaper as canting keel
*Sure, DSS is more complicated and more expensive as no DSS (at present, at least)
So what?
Someone is rich enough to pay for any gadget on his new boat.
Someone will decide to save money by using DSS instead of canting keel.
Someone will decide to remain in his familiar, tried and tested Melges24/Laser/IOR quartertoner/Star/Dragon/Folkboat/kiteboard/windsurfer ... .
So what?
...

 

Right you are.

Anyone who has been visiting this forum recognizes the hyperbolic claims made by a certain individual any time a new "technology" has surfaced.

According to things written on this BB:

Any owner who has a keelboat built without using CBTF is "nuts". Of course after this claim was made no more new CBTF yachts were built. Subsequently the most famous CBTF yachts have been converted from that technology, or are sitting on the hard for years.

All of us would be using kites instead of spinnakers. I don't know anyone who is currently using a kite in any yacht or dinghy racing.

We would be seeing production "peoples foilers" from prominent builders that would not require very athletic people to sail them. It's been years and we are still waiting to see the first one.

Canting keels with little wings on them would revolutionize the use use of canting keels on boats of all sizes. I recall 3 or 4 boats being built to try this out. IIRC, at least 2 were later modified and the other 2 have not been heard from in years.

There would be "bi foiling" keelboat sportboats sailing all over the place. I've yet to hear of one.

We would all be able to retrofit circular keels under our boats that would lift the boat, and provide lateral resistance. Still waiting for that one as well.


Shall I go on?


I like technology. I don't want to sail Cal 20s. If someone showed up with a foiling sportboat, or a tri like Gary's I would want a ride. What I object to are claims that things are "proven" before they are.

This isn't the first rodeo for some of us. I'm attaching a picture from a local publication. The article about it ends with this , "..it may not be long before we see speedy little foiler boats racing around the buoys int the breezier neighborhoods of L.A. Harbour or South San Diego Bay." The year? 1985. Still waiting to see those boats as well...

 

Well, that's it then. The Pope and the Luddites are all against us. Let's all give up and go home. I knew it was wrong to try.

At least I have a canoe to go home to; maybe I should start a movement to ban them new-fangled sail thingies . . .

 

err, one small, whispered point; compared to the complexity, arms race entrance, handling difficulty (and unreliability, shhhh!) plus great expense of the extreme draft canting keel, the new DSS (and other monohull foil developments), are a return to simplicity (in comparison) and therefore what follows, is not expensive ... and therefore should appeal to sailors who want uncomplicated, less costly, yet exhilarating sailing performance (and who does not like sailing fast? - anyone who denies this is lying like a Republican candidate) ... but here we're talking about change, means not following peers, thinking outside the box (sorry, cliche-d but true) - and not many people actually have the courage to move out into the open as individuals, fearful of hearing, "Please to step this way, gentlemen," - followed by machine gun bursts from CutOnce and the other "sensibles."
Hey, just slightly serious, tongue in cheek and all that.

 

Agree with Gary: For a dinghy adding a DSS seems like a less drastic step than tossing away the boat and building an entirely new foiler. Not much of a mod to a flat-bottomed plywood boat - just add a horizontal trunk sealed to the sheer planks under the seat or thwart o other strong point and bring a deployment/retraction cord up through a tube above the waterline. Done carefully the modification may even be reversible if you end up in Oopsburg - just seal off the trunk ends. Kumon Doug!