Design for DSS-Foil Assist for Keelboats

[ancient kayaker]

I wonder if they'll give me a quantity discount . . .

 

[Paul B]

New DSS design:

Nothing new here. These guys have been around for more than a year. Produced nothing so far...

 

[Doug Lord]

DSS- Mini Transat

Here is more info on the Mini 650 Proto Welbourn is working on-in German and English-scroll down for english(see pdf at bottom).

click on image-" sailing on foils is more fun"

 

[peterchech]

Here is more info on the Mini 650 Proto Welbourn is working on-in German and English-scroll down for english(see pdf at bottom).

click on image-" sailing on foils is more fun"

Nice write up thanks for posting Doug. I guess this is coming out of the theoretical and into the empirical sooner rather than later, should be really interesting to see the initial test sails.

I guess it's true, less than 2 years ago on this forum the idea of a mini scow was mentioned and everyone said it couldn't be done, too much resistance in the bow to cut through any kind of chop. At least on the mini transat (a mostly downwind race) this has been empirically proven to not necessarily be true.

Now that the concept is proven, will we see more scows in the next transat? IDK do you Doug? Or, a DSS scow LOL?

 

[Doug Lord]

Nice write up thanks for posting Doug. I guess this is coming out of the theoretical and into the empirical sooner rather than later, should be really interesting to see the initial test sails.

I guess it's true, less than 2 years ago on this forum the idea of a mini scow was mentioned and everyone said it couldn't be done, too much resistance in the bow to cut through any kind of chop. At least on the mini transat (a mostly downwind race) this has been empirically proven to not necessarily be true.

Now that the concept is proven, will we see more scows in the next transat? IDK do you Doug? Or, a DSS scow LOL?

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Peter, do you have a link to that thread?
Hah! Definitely not-I think.
==============
I found this older Mini Design Thread: http://www.boatdesign.net/forums/boat-design/mini6-5-design-2648.html

 

[peterchech]

========
Peter, do you have a link to that thread?
Hah! Definitely not-I think.
==============
I found this older Mini Design Thread: http://www.boatdesign.net/forums/boat-design/mini6-5-design-2648.html

Haha I don't have as much time as you do to look up old posts Doug, but if you do a search for "scow" on this forum, you will find probably tens if not hundreds of posts discussing the potential of modern scow designs, or at least discussing the advantages/disadvantages of the scow form generally.

My point was actually to bolster your assertions here, to say that there was (and probably still is) plenty of nay-saying by people on this forum to new ideas, and at least in that case the nay-sayers were wrong so maybe the DSS nay-sayers will be found wrong as well. At least there will be some empirical data now if this DSS mini is ultimately launched (and it looks on track).

 

[CT 249]

Haha I don't have as much time as you do to look up old posts Doug, but if you do a search for "scow" on this forum, you will find probably tens if not hundreds of posts discussing the potential of modern scow designs, or at least discussing the advantages/disadvantages of the scow form generally.

My point was actually to bolster your assertions here, to say that there was (and probably still is) plenty of nay-saying by people on this forum to new ideas, and at least in that case the nay-sayers were wrong so maybe the DSS nay-sayers will be found wrong as well. At least there will be some empirical data now if this DSS mini is ultimately launched (and it looks on track).

Well, I've had a quick look and I can't find many examples of people nay-saying scows here. "Mini + scow" as a search term shows basically nothing relevant until Raison's boat was already winning - no visionaries UNTIL the boat had proven fast, as far as I can find.

I don't really get what the problem is with "nay saying" stuff that has not been proven. I've always like Hugh's designs, but why is it "nay saying" to say that his designs are not always better? Sometimes it feels as if we are expected to just get the screaming wet hots for any new design, like a 9 year old girl gushing over Justin Bieber's latest release, just because it's new.

News just in - the fact that some people don't fall over themselves to praise any "innovation" as if it had no faults, is no reason to call them "nay sayers". Lots of stuff is over-hyped and only has narrow applications.

The closest we have to empirical data as far as I know is in Royal Port Nich, and so far the DSS version of the T30s is slower than the non-DSS version. There are certainly other factors involved, so I am not attacking DSS.

However, plenty of us are probably quite happy to say that we WILL "nay say" big claims that have not been proven. That is not being negative, that is being logical AND respectful of other designers and designs. It is taking into account the fact that other designers are NOT drooling imbeciles and therefore there may be reasons why they have not done this before.

That does NOT mean that we don't think that boats can go faster, but it does mean that we want proof. If you think people who ask for proof are "nay sayers" then I have a bridge you should buy.

All we are asking for is proof. Why is that so bad?


BTW few people have doubted that scows can be faster, certainly in certain conditions. Hell, my first boat was a scow, and yes I think that they are under-rated. However, they DO have downsides, as people like Herreshoff pointed out,

Maybe the "nay sayers" are not people seeking negatives, but people seeking a more balanced and nuanced idea of design?

 

[Doug Lord]

DSS Design

The real problem with "nay-sayers" is when they ignore "proof". Years of testing, the Quant 28, Brace, Brace, Brace and more to come.

http://www.youtube.com/watch?feature=player_embedded&v=DwDGKghV8fU

http://www.youtube.com/watch?v=D-ogozAZ24I&feature=related

----------
Proof of Lift

A foil for a 14' boat: area 1.5 sq.ft(.5' X 3')
a. At 1.34 X sq.rt. of waterline:
LWL 14.625=5.12 knots=67lb (simplified formula: L=v^2 X foil area X CL ,where L= lift, V= speed in feet per second, CL= coeficient of lift)
Lift X distance of Center of Lift from center of buoyancy=67 X 2.6875=RM=180ft.lb.
--
b. At 10 knots:
Lift =257lbs (simplified formula: L=v^2 X foil area X CL ,where L= lift, V= speed in feet per second, CL= coeficient of lift)
Lift X distance of Center of Lift from center of buoyancy=257 X 2.6875= RM=690 ft. lb.
For a nay sayer that's not proof at all: its only the scientifically substantiated fact that the foil provides lots of RM. Equivalent to a crew sitting 4' to windward of the CB. Want more "proof"-take the crew off the boat-what happens? Whoops-"all" that does is prove the naysayers point that if the foil magically and suddenly stopped lifting there would be no RM. Of course, in the real world thats about as likely as the crew falling overboard.....
But is it fast? You tell me: you have RM consistent with a crew sitting 4' to windward BUT NO CREW WEIGHT!! Not only that but since the lift acts vertically, it also reduces overall displacement, reducing wetted surface as well.
=====
The fact is that there has been lots of "proof" presented that proves that the DSS foil lifts, that it increases RM and that it reduces wetted surface. Racing results of two boats have shown that a boat designed from scratch with DSS is fast. And more on the way: 100' race boat, 50' cruiser racer, 21' Mini Transat 6.5 and possibly two more lake racers.
UPDATE,3/4/12: The three fastest DSS boats designed specifically for DSS are different and in different areas of the world so two boat testing has been impossible. But extensive RC Model testing, Tank testing and experience sailing has proven beyond a shadow of a doubt that DSS works and works well.
What I didn't know is that at least two of the boats have been extensively tested from tack to tack: one tack with DSS, the other with the board retracted. On the original 27 footer in 10-15 knots wind the difference upwind was 2 knots of boat speed. On each boat DSS showed improved performance as opposed to sailing without it.
In combination, all the testing and on the water experience has shown DSS to be a net improvement upwind and downwind on boats designed specifically for the technology.

 

[CutOnce]

The real problem with "nay-sayers" is when they ignore "proof". Years of testing, the Quant 28, Brace, Brace, Brace and more to come. <snipped for brevity - full comment one post up>

Proof is established scientifically, not anecdotally. When comparing a defined design element like DSS, two identical boats in all respects are needed - one of the two equipped with the design element in question - the other unmodified as a baseline reference.

Both boats are then run through the same trials, in the same conditions with enough cycles that representative data may be collected and results compared. If the new design element proves superior in all conditions (or a defined subset), then proof is established. Since the examples you've posted are one-of-a-kind boats, with no ability to compare results to a known baseline, it is pretty hard to concede "proof".

All the above demonstrates NO negative opinion about DSS - it is just establishing what "proof" means. I believe that DSS, under the right subset of conditions may "prove" to be faster than an unmodified example of the same boat. Chris249's post indicates the test Mr. Welbourne performed did not prove so (I have no knowledge one way or the other).

I'm not a doubter or nay sayer. Like Chris249 I'm on the fence, waiting for more thorough analysis and "proof" that passes the scientific meaning of the word, not the anecdotal standard it seems is enough here. Anecdotal evidence so far is pretty impressive.

Just because someone has a higher standard of "proof" does not make them a nay-sayer. It just means they have a different understanding of what proof means. I'm willing to bet Chris249 would be very happy to agree that DSS is a great technology if a more comprehensive and scientific evaluation, data set and conclusions were presented and confirmed.

--
CutOnce

 

[Gary Baigent]

Ah, the courage and foresight of the fence sitter.

 

[CutOnce]

Ah, the courage and foresight of the fence sitter.

Thank you once again Mr. Baigent for your thinly veiled condemnation. I do appreciate your consistent passive aggressive negativity. Especially when your ad hominen comment has nothing to do with the topic of the thread, or the content of the message above.

On this particular forum it takes far more courage to objectively point out both weaknesses and strengths as well as questioning details of new technology than it does to join the crowd cheer-leading unproven ideas. Even trying to establish agreement on a common vocabulary seems to be contentious.

From my point of view, declaring your opinion on a technology without adequate data, professional review and independent confirmation is fundamentally worse than sitting on the fence. It leaves the realm of science and engineering and becomes something I don't understand.

Cheers,

--
CutOnce

 

[ancient kayaker]

There's nothing wrong with being a nay-sayer and it's not an insulting term IMHO. I especially value nay-sayers who go to the trouble of trying to figure out what could go wrong with my ideas and present a cogent argument. They're not always right, but arguing with them brings out the best in us and our ideas and sometimes dumps the worst of them before someone gets hurt . . .

Advice from someone who tells me to "go ahead" without really thinking is worth its weight in BS! Having said that, there are some folk on this forum from whom a positive opinion - usually obtained at great length and after many a revision - is treasured in proportion to the effort it took to earn it and the advice received on many a previous project.

Lets hear it for the nay-sayers and their freely-given time and knowledge!

 

[Doug Lord]

Dss Design

I ran into this interesting boat today: http://www.boatdesign.net/forums/sailboats/sk-2-18-canting-keel-42121.html
It's an 18' canting keel boat. I had read that DSS might be superior to a canting keel and decided to check out what it would take to put a DSS foil on the SK2(see illustration below).
Very interesting results.
a) get rid of canting keel -leave ballast fixed on vertical, retractable fin with same area,
b) ditch daggerboard,
c) add .71' X 3.5'( 2.485 sq.ft) of exposed DSS foil (area less than canting keel daggerboard).
d) Results: (Note: max RM at 10 degrees angle of heel due to canting keel= 704ft.lb.

1- Upwind @1.34X sq.rt of LWL speed=5.75 knots:
--RM due to fixed keel @ 10 degrees= 264 ft. lb.
--Lift due to DSS foil= 140lb.
--RM due to DSS foil= 3.75' X 140= 525ft.lb.
--Total upwind RM using DSS(excluding crew)=789 ft. lb.
Note: less wetted surface, less induced drag, slightly more RM with DSS and no canting keel.
==========
2- Downwind at 15 knots, boat heeled @ 10 degrees:
--RM due to fixed keel @ 10 degrees = 264 ft.lbs
--RM due to DSS foil= 958 ft. lbs
--Total downwind RM using DSS foil = 1222 ft.lbs.
Note: A dramatic increase in RM(not counting the crew) of 174% allowing much hotter angles to be sailed, along with wetted surface reduction, and the other advantages of DSS in boat control.

click on image-

 

[Submarine Tom]

Ah, the courage and foresight of the fence sitter.

... or, is it the courage and foresight of the open-mined...

-Tom

 

[Gary Baigent]

Doug, how about leaving the dagger blade in the boat and dumping the bulb keel instead (replace with bilge water ballast tanks, which can be dumped when not needed) ... and then have a larger DSS foil?
Weight, as L. Francis or Uffa said, is only good in a steam roller.
Maybe the sensible naysayers adhere/believe too literally, the phases of a project:
1. Exultation
2. Disenchantment
3. Confusion
4. Search for the guilty
5. Punishment of the innocent
6. Distinction for the uninvolved