Scheel Keel

[JIO]

I am looking at a Compac 35 that has a scheel keel (created by Henry Scheel???) configuration. This keel has a 4 foot draft. I have both performance and safety concerns about this setup. It is my understanding that the Scheel Keel has been used on many different boats, but I do not know anything about it. Can anyone speak to this?

Thanks and I hope everyone has an enjoyable long weekend.

[Jeff_H]

The Scheel keel is a patented form of a bulb keel. The top of the keel is shaped to create an end plate effect reducing tip vortex and improving the hydrodynamic effiency of the shortened keel span. The bottom of a sheel keel is rounded to reduce wetted surface and associated drag. The bulb allows the center of gravity to be lowered.

In testing they are clearly not as efficient as a deep draft fin keel but are also clearly more efficient than the typical shoal draft keel or shoal draft keel with a bulb.

Jeff

[halyardz]

My Tartan has a scheel and it peforms much as Jeff notes. I''ve sensed some minor problems sailing close to the wind and recovering from tacks. Is this common Jeff?

[Jeff_H]

I am not sure what you mean by "minor problems sailing close to the wind and recovering from tacks" but I would think that the rig on the Tartan 33 is sufficiently efficient that the shoal draft keel would be the limiting factor on how high you can point. Pinching would result in increased leeway that would exceed that of the deeper keel version. When you tack all boats drop in speed and so the smaller area of a Scheel Keel and its need for good water flow to work might result in a few moments of increased leeway and a short lived soggier helm feel.

Jeff

[paulk]

Henry Scheel did a lot of research and experiments developing his keel, both tank testing and on full-sized boats. The fact that he was able to patent it lends credence to the idea that it is different from other shoal-draft designs. The fact that a reputable (and conservative) outfit like Tartan saw fit to pay Scheel a royalty for using his design instead of having their in-house designers come up with something cheaper that they could tout as a "manta-wing-super-shoal-performance keel" -- the way some builders do -- also points to it outperforming other shoal keels. There are always trade-offs. A ''real'' wing keel might work better than a Scheel keel for upwind legs, but it will likely have more wetted surface, and so be slower downwind, where the wings won''t be as useful. I also read about people with wing keels going aground in mud or on sandbars and having the keel act like a huge arrow, keeping them stuck when a simpler shape would have been able to twist off. If you had a centerboard, you could lift it and be off, but you trade space in the cabin, and possibly more things to break, like pivot pins and pennants. If you want performance, look at the racing boats and go for deep draft. If you need shoal draft, you are not going to get the performance. You have to decide the balance that suits your needs.