K-Wing
Bruce Foil Kayak Rig
Click to see a bigger image
The K-Wing is an English
"Bruce" foil based kayak rig (there also was a C-wing for canoes)
that is no longer manufactured. When I inquired around for details,
in hopes of making one myself I got this in return:
| The area of the foil should
be 10% of the sail area. The centre of area of the foil should be inline with the centre of area of the sail. The foil is canted at 45 degrees, the top of the foil being furthest from the boat, and its centre of area should be as far out from the centre line of the hull as the centre of effort of the sails is above the centre of buoyancy. |
Terse but informative
instructions. I was assured that the reason it was no longer made was
financial and not because of any performance problems. A couple of things
that are interesting but not obvious are that the foil is left/right symmetrical
in cross section and derives its angle of attack through leeway. Making
the sail and foil both mounted on a very substantial base isolates the
hull from the forces that the sail and foil are balancing.
Some other details that are clever are the roller furling mast and the
thin straps that attach the mast/foil step to the hull. You could probably
remove the whole setup in 5 minutes or less.
The interesting
thing about this foil is that it functions to resist heeling on both tacks
by lifting on one tack and pulling down on the other. The weakness of
this approach is that it is dependent on forward movement and leeway to
provide stability, and the righting moment is proportional to the forward
speed. So if you are in gusty winds or tacking a lot in high winds things
could be pretty exciting.
Adding floatation above the foil could help, at least on one tack, but
it is definitely a rig for the alert sailor.
Here are a couple
of other links with other interesting Monofoil rigs:
John Slattebos boats: http://home.earthlink.net/~dijslatts/
John Howes radical Monofoil: http://www.speedsailing.com/Boats_jons_boat.htm
Michael Schachts interesting Bruce Foil experiments (and much more): http://www.schachtdesign.com/proafile/volume_1/models.html