Canting Keel, DSS and Dynamic Control

Canting Keel

Jonithan McKeeCenterboard, swing keel, or keel, new monohull sail boat purchasers should at least consider vessels like Sadlers, Potters, Etaps and MacGregors that have solid flotation. They should also choose thin rather than wide monohulls. The thinner the hull, the more it is like a log in that it is self righting and of course the quicker the righting the less likely serious flooding.

Competing Hull Forms Bethwaite

The competing hull forms in Murrelet (displacement in the bow and planing aft) bring up some interesting aspects in sailing the cruiser. Because the manufacturer built so many pocket cruisers, the best hull form and ballast configuration was extensively studied.

Speed, Strong, Flotation = Safety

Speed is Safety

“Unfortunately, the speed range for typical displacement boats between 20 and 50 feet is only five to 10 knots- not nearly enough for many recreational roles. True, slow moving, full displacement vessels are reasonably efficient at carrying heavy loads because buoyancy forces sustain the weight for free, and only modest engine power is needed to slide it along.

Twin Shallow Keels

Twin keels become more effective with increased angle of heel, while a single keel becomes less effective.

“No other nation has put so much faith in bilge (or twin) keels as the British. Other countries have flirted with them, but we became so enamored with the concept that they were the first choice for anything less than about 36 feet.”

Practical Boat Owner
Buying A Second Hand Boat, April 2005, pg 54

Blue Bird, the first twin keel yacht, was<br /><br />
built in 1920 by Lord Riverdale. She was 25 foot<br /><br />
and had twin rudders not unlike a Mac26xIn light wind (less than 7 MPH) there is really no capsize risk in our kind of sailboat.

Planing vs Displacement Sailing

There are four modes of sailing. Displacement mode, forced mode, planing, and the 4th mode. Obviously many ocean sailboats do not plane and hence there is no reason to learn sail planing techniques on those boats. In fact it is just the opposite.