Scheel Keel and licence fee

[Mikey]

The Scheel keel is still protected by a patent and so there should be a licence fee involved if I want to use it.

Pro’s - Any information on this?

[Eric Sponberg]

Mikey,

As far as I am aware, Mr. Scheel passed away some years ago, so to license the Scheel keel you would have to deal with his estate. I don't know who that would be, probably some of the family. Others may know more details.

In my opinion, the Scheel keel was an early attempt at a bulbed keel of sorts, and I think later generations of bulbed and winged keels provide better performance.

Eric

[Mikey]

Eric,

I read that you now can get Nautor’s Swan yachts with Scheel keels. Nautor are really really conservative so if they offer it, then it got to be good in some ways. Maybe not for max performance but how about overall a good choice for ocean cruising.

Thanks for advising me “Seaworthiness, the forgotten factor” a while back, extremely interesting reading, read it so much that it is starting to look old now. That book is the reason why I want to know more about the Scheel keel.

I am researching/doing an ocean cruiser design so I think it deserves some time, anyone has some more information about Scheel keels?
License information?

Mikey

[Eric Sponberg]

If you study the Scheel keel design, you'll see that the two factors that make it work are 1) low center of gravity, and 2) a shape that promotes somewhat of an endplate effect. Newer bulb designs are even more pronounced in shape to lower the center of gravity even further, and to give an even better endplate effect. Since the advent of the Scheel keel, some towing tank and CFD studies have been done (mostly privately) that confirm these effects. That is why I say the Scheel keel was an early attempt at some form of bulbed keel. Before the 1983 America's Cup when Australia II sported a winged keel, bulbed keels were not very well known or understood. After 1983, there was a virtual explosion of bulbed and winged keel designs.

Scheel keel is old technology, but the name may still have some marketing cache. That may be why Swan still offers it.

Glad you liked "Seaworthiness, the Forgotten Factor". I consider it required reading for anyone practicing sailing yacht design.

Eric

[Mikey]

Eric,

OK, sounds fair enough, Scheel has been around for a long time.

Not sure I like winged keels on ocean cruiser designs but dropping Scheel and go for bulbed keel would also help in another area, the problem I have keeping 6' draft and still have good stability. Lowest possible CG is a high priority.

Seaworthiness is my main priority, I will gladly trade the last top percents of speed for that.

Many Thanks Eric
Mikey

[SeaDrive]

Compared to many of the alternatives, the Scheel keel has a minimum risk of damage in grounding or of getting in a tangle with pot warp.

[Mikey]

SeaDrive
That was one of the things that I really liked with the Scheel keel, and you can almost stand the boat on it too, no dragging the Sargasso Sea with you either, good for a cruiser design. Bulbs sticking out fwd of the keel are out on a cruiser in my opinion, all kinds of things get stuck. I don’t like winged keel on cruiser design for the same, or opposite reason rather, can too easily be damaged in grounding.

A bulbed keel should give me more of what is needed the most, low CG and damage when grounding is still small. What do you think about my reasoning, do you agree?

Mikey

[SeaDrive]

Originally Posted by Mikey

What do you think about my reasoning, do you agree?

The Scheel keel is workable and practical. To say more requires comparison to some other fully described alternative, which could be keel/centerboard, some particular bulb or wing, or some other patent keel. Comparing a specific to a generality is not going to be helpful at this stage.

[Mikey]

SeaDrive,
I have been jumping ahead, I simply don't have enough specific information available at this stage. What I have now is only that it is surely going to be a rather low aspect ratio keel, NACA 6 series, maybe 65010-12, centerboard is out because of complexity and that I have problems keeping 6' draft with acceptable stability => it will have to be some sort of bulbed keel.

I will post again when I get closer.

Thanks
Mikey