Design for DSS-Foil Assist for Keelboats

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I'll ask Jeff......

 

Might be easier with less impact on resale value to experiment with a lifting sail - maybe a lateen . . .

 

DSS cruiser racer

You guys may not know about this boat: http://www.jkyachts.com/home

 

I haven't read anywhere that the angle of attack on the DSS foil can be adjusted. Can it? While Sailing?
HW says the foil is either all the way out or all the way in so it doesn't sound like you use a a varying amount of DSS depending on conditions.
Haven't read specs on the Mini but guessing as they need to stay within the 3M width rule that the hull beam will be a little under 2M and it does not have a canting keel. So a lot of the RM will be coming from that foil.
A question for people smarter than me. What happens if the heel increases, say you get a big gust, the foil is now more vertical, lift is not as up anymore, what happens?

 

What we do know about that boat is it has been more than a year since the date they claimed it would be sailing. Maybe closer to two years...

 

Dss

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Where did you find this?(see below)
With a big gust the boat may heel in the seconds before increased speed results from the power of the gust. In those seconds the keel bulb moves to windward instantly adding RM during the slight lag between gust and increased speed....
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UPDATE: Sean, I found one mention by Welbourn-things change and that is simply not the case anymore on every DSS design:
http://www.harken.com/Interviews/DynamicStability.php

Is the DSS something that would be adjusted depending on the TWA, similar to the way one would adjust a centerboard? ?

HW: No. The system is simple in that either the foil is fully deployed or it is not required.



Obviously not the case on the Quant 28:

 

It seems the angle of attack is fixed. So when sailing in waves and the bow pitches down the foil is also pitched down and it appears to drive the bow down. Here's the video of the DSS 27 sailing in waves and porpoising like mad when the foil is alternately loaded in a "pitched down" attitude versus the unloaded foil attitude.

http://www.youtube.com/watch?v=e9OZiSvBMu0&feature=fvsr

 

Dss

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Surely you're kidding!!! Not only that but close observation will clearly show that they are using variable amounts of foil....
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Not possible for the angle of attack to be "fixed" since it is controlled by the pitch attitude of the boat ,waves and other factors. The angle of incidence is fixed on many(but not all) DSS designs.

 

Considering the amount of sail power they were using that was a remarkably upright boat - except for one dramatic moment. I wondered if the foil was being varied for test purposes but could not see if that was so. There seems to be plenty of lift from the foil, which can be seen from time to time. DSS adds another thing for the skipper to worry about so the cailms for additional comfort are unlikely to sell it to folk who could simply and more safely reduce sail or hove to. The speed will either sell it, or not.

 

I think it's highly unlikely that you can adjust the angle of attack while sailing. That'd add a whole new level of complexity to the system.
Interesting point that as the boat pitches the angle of attack changes. That can't be good.
I saw the video that PaulB mentioned. I blinked and missed them wiping out, looking at it again that didn't seem normal. Goofy looking boat, awful long skinny, slab sided bow, doesn't look like it picks up any reserve buoyancy.
All these sportboat videos where they just reach around in breeze don't tell you anything. Ya, we're fast on a reach, whoopie.
Also the Quants and BraceX3 are sportboats where everyone is working hard full time sailing them, trimmers are trimming like mad and steerer is steering like mad just to keep them going. A Mini is a whole different deal, one guy can't do it all full time, the boat has to help.
PaulB is right about lack of updates, I've looked around not much recent news. DSS website recent news is 2008

 

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You can adjust the angle of attack of the foil by changing the pitch attitude of the boat with crew movement. You cannot adjust the angle of incidence on any current DSS boat that I am aware of.
That kind of comment on a design forum seems sort of out of line for a well designed, fast, experimental boat....

 

That's why I posted the video. The bow pitching down like that doesn't look so fast.

The wipe out does look odd. I've sailed on sportboats and none have ever fallen over like that.

I believe the designer had said it was a scale model of a proposed 100 footer. That's why it looks the way it does.

If I went out on my boat in 20 knots and reached around with 4 guys on the traps I would have a video that looks as fast or faster than the one of the DSS 27 I posted.

I would love to see another Quant popped out of the mold, only without the DSS. Then spend a year racing the two boats in all sorts of conditions against one another. That would tell us something about the validity of the concept. Something tells me the people selling the concept would never do this.

You might remember the 8m canting keel sportboat a few years ago. The simpler, fixed keel versions seemed to be faster than the canter sisterships.

 

It's unrealistic and impractical to think you can change board angle of attack by adjusting boat pitch, theory maybe, sailing, no.
Didn't mean to get you worked up by saying I thought it was goofy looking, it's just an opinion. There have been some goofy looking boats that were fast. Actually PaulB might have explained it. If the 27 was a scaled down concept of a big boat the proportions might be odd.
How do you know that boat is well designed, fast? Just by watching his vids?
Since you seem to know about DSS. Do you know why there are no DSS board slots in the pics of this JK? Pics #13-14, the only pics of the actual boat
http://www.jkyachts.com/#!__gallery

 

If THIS is "porpoising like mad", what is "steady", than ?

 

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1) Is that right? Guess it depends a bit on the crew and the size of the boat, huh?

2) Slots?! I can see the foil position clearly-you can't? Of course maybe they've changed their mind and are deliberately camoflaging the foil position so the news doesn't get out.

Because I know Hugh Welbourn and have read about and studied this system and the boats its been used on for years.