Keel Ailerons

[Inquisitor]

Now, I’m an AE and prone to mental lapses in other fields. I’m sure since the thought just hit me while reading other stuff on this forum, that it may have already been invented and tossed. Since, I find multihulls more endearing, I don’t really have the bandwidth to pursue it…

So be gentle to me…

My understanding: These deep keel things with big weights at the end do two good things:

1) Weight - provides the righting moment to keep you all from swimming home.
2) Fluid Dynamics - keeps the boat going more in the direction it’s pointing instead of the way the wind wants.

… and two bad things:
1) Add tons (literally) of weight.
2) You still heel. (The only heeling I do is to fly a hull for fun.)

So… why not use fluid dynamics to replace some or all of that weight? The following picture is labeled since the drawing sucks. It could also use some nice designer so it doesn’t look like a barn door on a Ferrari.

With water’s generous Reynolds number, they shouldn’t need to be very big nor deflected very much. It seems like you could induce enough moment to eliminate or even heel into the wind. That might even help lift the boat out of the water further reducing the hull drag.

Just curious.

[jam007]

There is a problem here. To create moment against the heel you need to create a force in the same direction as the sideforce of the sails. This will increase the leway. The increased leway will create more lift by the keel and also nessesitate more deflection to create enough force to counteract the heel and ....

The net effekt is only to increase drag and cancel the sideforce counteracting lift created by the keel. You will end up sailing like you had no keel and with a lot of extra drag from the ailerons.

Multihull is a MUCH better solution.

Anders M

[Jocko]

I believe the pictured keel concept suggests implicitly that the lowest 'aileron' be deflected such that the keel be forced down and to leeward, while the upper 'aileron' be deflected opposite - up and to windward. The greater deflection of the upper surface would offset the effect, allowing the keel to still function effectively preventing leeway.

[stewi]

If you use a kite instead of a sail and mast, you wouldn’t heel either. Use your expertise in AE and design a kite sail, which can do better than 90 degree to the wind.
Than, don’t forget that I told you and share the profits with me.

[Stephen Ditmore]

The idea you describe was patented in the U.S. and dubbed the "Cohen Keel" around 1990.

My patent improves on it, I think, by having a winglet that can be positioned on the windward side with an aileron creating a downward force. This would only be done when sailing upwind in a strong breeze, when the additional stability is necessary.

[Inquisitor]

Originally Posted by Jocko

I believe the pictured keel concept suggests implicitly...

Exactly!
I forgot what forum I was on and assumed everyone knew what an aileron did… the basic premise being they only cause a moment and NO translation. So “implicitly” was a nice way of saying it… I was lazy.

Other explicits…

• The hull and bulb should be modified to form end plates to avoid the energy robbing vortices.
• That is why I made it go down to a point between the two keelerons. No vortices from the inner ends.

Although, I note that you enlarged the top keeleron – very astute… properly scaled, might produce more lifting out of the water (reducing hull drag) and might even permit sailing closer to the wind. Just a theory… not really my expertise.

Several things are a certainty.

• Sailing upright certainly will provide far more power than heeled over 30 degrees.
• Reducing or eliminating tons of weight will certainly reduce hull drag.

It would be my belief… far more than the drag induced by the keelerons. Maybe if no one can find some flaw, I might have to drag out my Abbott & Doenhoff. But the problem would then be, I still don’t want a mono.

[Inquisitor]

Originally Posted by Stephen Ditmore

The idea you describe was patented in the U.S. and dubbed the "Cohen Keel" around 1990.

My patent improves on it...

I would assume you know the theory and practice backwards and forwards. So there must be some technical reason why we don't see boats using it? Hopefully, you aren't going to tell us that it was banned by some governing body. Guess it'd be a little hard to hide with your mast sticking strait up...
Oh, who me occifer... I ain't got no stinking keeleron!

Just technically curious... wondering if my gut feelings are right... I don't really have a dog in this fight.

[Stephen Ditmore]

The type you (and Cohen) describe only works if the keel is large (because the net lift to windward must be the same as a keel that doesn't work against itself) and very deep (to make it efficient enough to be worth it). Multis already have an advantage when it comes to draft.

I think my varient has merit for megeyachts that are concerned about performance and draft, but I acknowledge that some mechanical complexity is involved. A lump of lead is a lower tech (cheaper) solution. For the racers, a canting keel has it beat.

IQ, using a foil or foils on the keel to reduce ballast has a LOT of merit!
Stephen Ditmores patent(6,453,836 B1) is a brilliant solution for fixed keels(though I think it could be adapted to a canting keel) but I think the best I've seen is patent number 5,622,130 by Alberto Calderon, Charles Robinson,Bill Burns and Matt Brown who also invented CBTF.
This patent separates the functions of RM from that of lateral resistance using CBTF but goes a step further in having a trim tab like foil on the back end of the keel strut used to generate downforce when the keel is canted 60° to weather. So the canting keel reduces the required ballast by 40% or so and the flap on the strut can reduce it even more-substanially more . The chart included with the patent indicates that the flap could reduce the ballast on the end of a 60° canting keel strut up to 50% if I'm reading it correctly. The shape of the trailing edge "trim tab" is very narrow at the top close to the hull and maybe 2.5 times that chord close to the ballast. According to the patent it has another great advantage in that the flap can be moved very quickly and therefore the whole system's response to gusts would be greatly improved over a "normal" canting keel.
I'm convinced that a boat built using this patent or similar technology would be one hell of a fast monohull and probably a good candidate
for using hydrofoils-at least off wind.

[Inquisitor]

I'll have to dig those patents up.

Not that I run in circles to have seen these in use... are any of these being used and if not, why?

[disciple]

Grab a piece of A4 paper ( if you guys have one to hand) fold the two shortist ends together then slide one along the other keeping the edges together, who needs Ailerons ?

IQ, I'm fairly certain CBTFco is actively developing this system and boats using it could be amongst us before too long.
The biggest design problem may be to insure the selfrighting characteristics of a "keelboat" using this system...

[Inquisitor]

Originally Posted by disciple

Grab a piece of A4 paper ( if you guys have one to hand) fold the two shortist ends together then slide one along the other keeping the edges together, who needs Ailerons ?

Now that's what I'm talking about!

That's back in my field... active wing shaping.

[yokebutt]

A4 paper? Is Britain becoming civilized?

Y.

[disciple]

Inquisitor 'active wing shaping' what a great description I'm going to use that in a search engine. I've been thinking, let's pretend the fact that the boat would flop onto it's side doesn't matter and take away all possible weight from the keel. What would be the benefits, the boat is much lighter so don't need so much boat, not using the beam to help counter weight of keel so don't need so much beam. The savings so far would reduce the need for so much power from the sail, less roach. You would end up with one side of a cat hull. The faster you go the greater the lift from each section of keel i.e. less drag. It would be like having the option of more or less weight in a conventional keel depending on wind conditions and or points of sail.