Horizontal Keel

[adbert]

Hehehe I'll leave it to you guys now. Getting into too much technical which I'm not familiar with as yet. I'm a newbie after all. I'll read more sailing/yacht books before I can chat to you guys.

[ancient kayaker]

The horizontal appendage on the keel you showed in post #7 increases the lift/drag ratio of the keel. It works by reducing the water flow that "rolls" off the tip of the keel, causing turbulence and hence drag. It is similar to wing tiplets used on many passenger aircraft. Definitely for the performance obsessed sailor.

I supposed you could shorten the keel with this device fitted but if you want to use a boat in shoal and tidal waters you may be better served with twin bilge keels. I doubt it would work very well if this 'wing' were run along both sides of the yacht full length as you suggest, and I can't see how it would do much of anything above the waterline except maybe as a party-sized swimming platform. Wider, narrower wings mounted above the waterline and angled to provide lift will theoretically work as a wing when one only is immersed by heeling, but if you hit a wave strange things will happen. Bit of a nuisance when you try to dock!

[robherc]

Originally Posted by Chris Ostlind

If there is a specific bulb jockey on the boat, then it might be done simultaneously. It could even be designed to use an auto-slide function in the electrics, or hydraulics, whichever moves the bulb, and that would coordinate the movement rather than a crew person. Still, that method would probably not move the bulb horizontally until it is at its very limit of travel.

I think Davide said that there was going to be an automatic system for moving the ballast, but I'm not sure if it waits until it's a horizontal movement, or if it triggers as soon as the boat begins to heel.

Now, if my eyes are fooling me and the fin arrray is actually horizontal as built, rather than angled downwards at something like a 40-45 degree inclination, the bulb could be going horizontal all the time unless the boat is heeled, which is very nearly all the time when sailing. Perhaps Davide can clarify that point.

According to Davide's numbers, the keel wings are angled down about 25* from horizontal. That's about half-way heeled-over for it to be a horizontal-motion of the bulb, but it is at least a LOT more feasible than 45*.