Mini Ocean Racing Scow

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I don't like the bow-I think Raisons is far superior.

 

Pacipat 650 and Pacipat Open 40

Found it: this company produces or will produce two designs. The pictures in post 104 show renderings of the Pacipat 40-much closer to the Raison concept. Below are pictures of the Pasipat 650-note the transom. The 650 was designed way before Raison's transat victory..... http://www.pacipat.com/

Pictures: Pacipat 650-click on image-

 

Very interesting

 

The renderings below show a Class 40 with very full sections forward but not quite what Raison did. But I'd imagine the key to Raisons success(like any scow) is movable ballast -and canting keels aren't legal in the 40's. So I don't see this design being anywhere near as successful as Raisons 747 scow.

click on image-

 

I imagine it would be quite fast in any down wind race. It would have most of the advantages of the punt, but a slightly shorter heeled waterline. It would have enormous initial stability.

Unfortunately, it would have similar initial stability upside down.

It is kinda like Joshua Slocums 'Spray' gone on a severe diet, as it has what used to be called an 'apple bow'.

To make it 'self rescuing' would require strategically placed buoyancy tanks and flooding the hull, if it ever capsized.

I don't know if sail area is limited in 'class 40' design rules. This boat could carry an enormous rig and stay quite controllable even if pushed hard, especially if it were equipped with twin rudders.

 

- perhaps the weight of the movable keel would help righting the boat after a flip; it would already be high if it had been raised to windward if the boat was blown on its side, so it could be lowered under gravity in the event the mechanism was disabled by the knockdown. Maybe it could even be used to roll the boat all the way over if it turtled.

 

When heeling:
Strong Reduction of Cp, WA, BWL
Reduction of Cb
Increase in LWL
Strong shift of CB to leeward, while almost no longitudinal movement
Strong increase in GZ (as scow), much more than a thin bow design
No longitudinal movement of CF
Sectional Area Curve fills to forward (max. section 30cm forward)

As I see it, this ugly thing can stand more sail area by more time, spends less energy rolling in each puff (energy that turns in thrust), increases his RM faster when heeling, while reduces his WA and BWL as well as a thin bow.
The increased resistance facing chop is less than the increased power of the whole concept.
It works. As Doug, I'm starting to see it with new eyes.
Think on all that interior space for the same LOA, it can change forever the cruiser design: you could have a 20' with the interior volume of a 24'.

 

Raison Scow

Great info, quequen-appreciate it!

 

thx for the e-fort, quequen

the heeled wet areas support what I got beaten-up for before -- my suggested ideal shape is two windsurfers, port and starbord, with the blanks morphed in.

my issue is this: the surfboards should be moving in their logical direction, but the directionality of the keel&canard (more so canard as keel is nearly horizontal) will attempt to pull it to windward causing conflict

solution: rotating canards will allow it to "slide" to windward

question: does this account for the pulling effects of the sail and tipping effects of the mast and gravity? is that important?

jb

 

Rotating the foils in the hull does not change the angle that the foils move through the water or the angle at which they move relative to the wind. All it does is to change the angle of the hull and the rig relative to the water and wind.

You mentioned windsurfers, and they provide a very easy demonstration of this effect because the angle of the foil is completely flexible compared to the angle of the rig. If you rotate the nose of the board to windward to angle the centreboard and/or fin to windward (that is, closer to the wind than the normal sailing angle) then the board just slows down or stops even when the sail remains at a constant angle to the wind; the board does not "slide" to windward.

And that's in a shallow-hulled windsurfer. In a boat, where trying to "slide" to windward means making a deeper hull move sideways across its path, the drag would be even higher.

There have been trim tabs and gybing centreboards around for decades and these effects are well known - such devices alter the orientation of the hull but do not allow it to slide to windward.

 

Some of the old scow Moths had hulls that were effectively wider on the waterline near the bow than near the stern. Using that principle, you could design a hull which effectively rotated to leeward as it heeled (opposite to a conventional wedge hull), which would obviate the need to rotate the keel to get the gybing centreboard effect.

 

If I understand well, what Human 1.0 proposes is: once the daggerboard earn enought lift, you can skip the small lift provided by the hull and rotate it to a position of least resistance, aligning the underwater body with the flow.
Human, CT, perhaps you allready know the 1999 3Dkeel. François Lucas, who was a colaborator with David Raison, claims his effectivenes in all directions of movement. Don't know if the M747 has this system, if it doesn't we should ask why...
http://www.fr-lucas.com/base_1071.aspx#Ancredetail

I wonder if this helps to what Human 1.0 proposes, as the keel is canted to a high angle most of the time...

 

qq writes: if it doesn't we should ask why...

I'm sticking w/ my theory! (or hypothesis -- ct429 thinks I mean left to right -- I mean like a rudder but only a few degrees)

 

Human, I know you meant like a rudder. That would mean that it would effectively be a gybing board or like the Carter pivoting keels, and the way that they work is quite well known. They don't slide to windward, instead the foils stays at the same angle of attack and the angle of the hull and rig changes.

 

@ct249, eh, no, you don't get it, not by a long shot

This is why I give version ratings here -- ct249 is rationally reducing the "abstraction" (or theory) to bring what (he thinks) is the "socratic dialog" to a level (through antithesis) that (he thinks) you can win (and thus get "points" for "synthesizing").

ct249 gets a human version rating of 0.1 (which means he is fully-devolved) as he presents a really bad case of "Captain Bligh syndrome" (CBS) -- not to mention pathological metacognition