16' Keel boat-high performance

water SDB

If you used a buoyancy pod on each end molded into a hollow curved wing you might be able to get the water from side to side by raising the windward side(automatically by sliding the wing to weather on a fixed trapeze wire or by physically lifting it by shortening the trapeze wire manually) and then release a large valve or something. You absolutely need proportional control of the position of the ballast and you could have it by moving the wing side to side with the ballast in the pod-but it would be somewhat awkward at less than max extension I would imagine.
If you compare the volume of space taken up by a sliding piece of lead(as in my system) to the volume of a container(as in Raggi's idea) you'll find the water taking up a little over 10 times the space of the lead which would make for a long or wide(or both) container within a large wing.
Th 18' version needs 220lb. of ballast and the 12.75' version needs around 76 pounds.
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I'm fairly well convinced that in order to do a high performance version of this system you need quick, precise movement of the ballast and you need the wing to stay sealed without question. I don't think water ballast would work too well because of the space it takes up but especially because of the problem in moving it side to side
reliably in all conditions on this size boat.
Bethwaites "MaxiSkiff" is planning on it ,I think.

 

It's my opinion that water ballast is not really workable for fast and repetitive tacking racing boats. There's just too many issues to deal with. If you are talking about a big ocean racer, like the Vendee Globe or Around Alone style of machines, then it works out beautifully as the boats stay on one point of sail for extended periods of time and the physical issues of moving water around are not as critical.

Rapid movement of water for ballast in a small boat would require a serious pump, a serious battery for the pump and serious added weight from both to make the whole thing work properly.

Chris

 

Doug:
Wouldn't the Bongo be an existing example?
http://www.sailabongo.com/m/_general/default.asp

 

Bongo: not quite

Stephen ,the Bongo is a singlehanded keelboat alright but doesn't fit the bill here because it's not a "sit inside" design like the 2.4 meter. You have to sit on the rail and hike and crossover and sit on the other rail in a tack or gybe. The thing I'm trying to achieve here is a boat that can be sailed as easily(more or less) as a 2.4 meter but that will offer planing perfomance at least off the wind if not also upwind-as the two previous SDB examples are theoretically capable of.
I envision a boat that an able bodied or disabled sailor can sail but with dramatically greater performance than any of the "sit inside" singlehanders now offered including Bethwaites "Lead Assisted Skiff"-UD 18(sort of "sit inside") , "Access Dinghies" and the 2.4 meter boats.
I've become convinced over the last few months that an SDB (sliding deck ballast) boat offers tremendous potential for this type of boat-way outstripping anything possible with a fixed or canting keel.It gives the single hander the power of a "crew" standing on a rack hanging from a trapeze.
What do you think, Stephen?

 

Hmmm. I'm not familiar with all the boats you mentioned. My only experience actually sailing a "sit inside" boat was a Windrider 16 demo sail, and while the boat is cool looking and I respect Jim Brown, I didn't love it, and would rather have had the option of sitting on the tramp and using the cockpit as a foot well.

I'd still love a chance to sail a Rave, but as far as seating I'm more enthusiastic about Hobie 18 style sit-down racks like your foiler has. I do find the Bolger Bridwatcher and it's big brother, the Weekender, interesting, and I like the idea of sailing a small boat that can be warmed.... as a way of extending the sailing season.

 

sliding deck ballast

Steven, I like the sensation of speed you get when sitting low dow. I had a little tri that I could sit up on a solid tramp(with legs hanging down into the cockpit well) or down low in a seat. It was pure exhileration sitting down low. I generally like the fact I'm on a boat so I'm not too picky except that I really dislike sitting on a flat tramp!
But what is your impression of the concept of using sliding deck ballast inside a sealed wing with buoyancy pods on the ends as I described earlier?

 

Why not just make a tri with movable ballast?

 

tri

Heavier, harder to handle for trailering, can't be made self righting,capsizable,pitchpolable, much more expensive. A tri that was designed to fly the main hull w/o movable ballast would be a lot of fun though.

 

but if it has buoyancy pods it will essentially be a tri.
And if this thing with "pods" flips, its not going to be righting itself in any hurry.

Just strap 3 kayaks together with carbon or fiberglass crossbeams, and find a rig to put on it. No monohull under 20 feet is going to perform like a sportboat if the crew stays in the center of the boat.

 

sdb performance

2, you used the same argument with the Bethwaite and Langman "Maxi Tri's" and it's flawed. Those boats and my boats don't sail on the buoyancy pods-they're just there for back up . With my boats or the two "Maxi Skiffs" it would be plain SLOW to have the pods in the water.
I doubt you read the technical description of the two boats I proposed earlier because the 18, for instance, has a SA/D ratio of 48-damn close to the International 14 and the 12.75' version is comparable with the 505 & FD-both with a 250lb max crew(at that ratio)! And capable of being sailed by crew as light as 90 pounds at skiff ratio's. Both have SCP/Total Weight ratio's of 30% with a max crew. With that ratio these boats are much closer to skiff performance than to "sportboat" performance-capable of upwind planing and probably foiling. For instance, a Melges 24 has a SA/D ratio of 33.74 upwind,and as just pointed out the 18 SDB's SA/D is 48, the I14 49 and the 49er 51.7!
You said "no monohull under 20' is going to perform like a sportboat if the crew sits in the center"- not too well informed an opinion as to the potential of these boats. Of course, my version of these boats hasn't sailed yet but the numbers speak highly of them.

 

You didnt answer what would happen if your proposed boat flipped. It seems to me that it wouldnt want to right itself.

 

sdb performance

If the 18 took a knockdown with the wing at maximum extension to windward it would right itself slowly and faster by sliding the wing down(to leeward) since the wing has massive buoyancy.The weight would assist in righting the boat by first causing the wing to want to slidedown(assuming the boat at 90°) and second as RM as the buoyancy pushes the boat up. In addition to the leeward buoyancy pod(close up to the side of the boat with the wing at max extension) the 18 has a weighted daggerboard with 75 pounds at 5' below the boat which also assists righting.The 12 footer would be righted solely by moving the wing down with buoyancy in the leeward pod and in the mast preventing turtling in both cases.Neither boat relies on crew weight to right it.
At least that's the plan.I'm sure there are things that will need tweaking but the concept has captivated me because of it's performance potential and what that could mean to disabled and ablebodied sailors alike. Both boats can be sailed at a high performance level with a crew weight range from 90-250lbs and the concept offers accurate weight AND righting moment equalization for competition along with a rather new way to sail.

 

18' skiffs

Here is a pic of an 18' with self adjusting ballast

That's alot of ballast and righting moment for a little skiff

 

18

Sure is-but just out of curiosity: what does it have to do with the subject of this thread?
The idea here was to come up with ways to power up a singlehanded SIT IN keel boat-like a 2.4 Meter but much,much faster....

 

isnt the Martin 16 or whatever its called much faster than a 2.4 metre?