2015 IMOCA 60-Foil Assist

2015 Imoca 60

This has happened before on various forums. An anonymous person comes to the forum and authoritatively disses a famous persons patent(or whatever).
The gut reaction is to dismiss such a comment as not worth even discussing.
In my case, I've got several patents and many more "patentable" boats/devices, and I've given up on the patent system though it was a real blast getting that first patent. Now, I publish my ideas in detail so as to make it available to the most people. But,in my case, there is still more: I know Hugh Welbourn and understand what he has gone through to protect DSS. I trust his judgement and guarantee you that his work is very well protected-and further ,I hope he shuts down any thieves that creep out of the sea bottom.
So lets get the topic back on why the BP system will work-or not work compared to what DSS can do for a race boat.

 

Comanche foil

I found this foil render in Pro Boat courtesy of VPLP-Verdier. It is a foil that was proposed and apparently discarded for Comanche:
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Check out this picture of Safran-particularly the foils-just launched:
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Ahh that beauty the dare the sin!

 

2015 IMOCA 60-Foil Assist---Safran

Picture just after launch showing the removal of the foil cover. Hard to believe that that vertical foil replaces the previous huge daggerboards?
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When it is pulled out it will. Nice to see rapid development in real-world.

 

Beyond the loss of area there is the loss of aspect. I can't help but think the keel is providing more leeway resistance than it did in the old daggerboard boats.

 

Actually, because of the up-angle of the keel pivot axis it's probably providing less lateral resistance than in the past-at least close to max cant. There was an article in Seahorse magazine a couple years ago that the up-angle reduces drag but also allows the keel to develop a small amount of vertical lift-completely counter intuitive because that small amount of vertical lift slightly reduces RM.

 

I don't know the details of this boat but my comment assumed that the keel would cant less because the foil is providing far more righting than in the past.

old boats -keel provides righting, boards resist leeway.
New boat -boards provide more righting, keel can provide more leeway resistance.

Do you know what the canting angle is on this new boat? Keel dimensions?

 

Open 60's 2015

I don't know any details except that they have about a 3-5 degree up-angle to the canting axle. I'm fairly sure they would use max cant before and if they gained enough from the DSS foil they would take out weight in the bulb. The problem with that is they still have to meet the self-righting requirements of the Open 60 rules where keels have been made one design so you could be right but I doubt it.
I think canting angle is 40 or 45 degrees.

 

Then comes the gain on balance, which is nice. The canted keel is to windward, and now the sideforce business is leeward. That equals good news on boatspeed.

 

There is no question of placement, which is good, the question is what will provide that sideforce? The reduction in area is substantial and even worse the depth -reduction in swept water combined with the loss of endplate effect. I can see a little positive effect from high pressure at the end of the horizontal section but I don't see enough lateral lift for upwind work. This boat looks like it would be ornery upwind -loss of speed results in the simultaneous loss of righting and leeway.

On the bright side this boat will scream with good wind on the aft quarter.

 

Guessing that there is a gain comparable to enplate effect in the smooth 90° kink in the foil. As itself the sideforce portion looks about same size as the leeward rudder. It is tiny like you say.

 

I think we need to have a new view to the combined lift/sideforce foil.

The AC 72 foil as stationary has an understandable vertical and horizontal portions. But speeding over 20 knots, the combination bends 30 to 50 degrees. That should be a loss in sideforce, but no! Only when the wingtip is surfacing, we see leeway.

Comanche got Oracle's AC hints and maybe we are seeing some of it here, too.



(Sorry for double-nick, i'll clear it asap.)

 

guys, im pretty sure that configuration could work as a full foiler. it's basically the same as a J foil when extended and when the boat is heeled. could be pretty interesting, look for an on-the-fly angle of attack adjustment system!