AboutKeith Graham Expertise I have been sailing for 40 years in boats ranging from the 8` El Toro, the singlehanded Olympic Class Finn, to Snipes, Thistles (which I currently own) Thunderbirds, Excaliburs, Mermaids, Cal-40s, 6- and 12-Meter yachts. I have skippered, crewed, designed and built sailboats. So, if it`s a question about sailing, I`m your expert!
Expert: Keith Graham Date: 12/11/2006 Subject: sailboat performance indices
Question Are the Ballast/Displacement and LWL/Beam ratios reliable indicators of a sailboat's stability and stiffness? Of what else, if anything, are they indicative? Tx!
Answer David,
Reliable indices? General guidelines!
Read some of the books on sailboat design and you'll run into a couple of horror stories where a boat that was design to be stable, wasn't, and vice-versa.
Generally, the heavier the boat is, the more stable she is, but the weight has to be placed correctly. The loer the weight is placed, th "stiffer" she is. Stiff is not totally a goal as a sailboat needs to "heel" (or tip) over in order to spill wind from the sails when the boat is over-powered.
The longer the sailboat is at water-line, the faster she can sail. A longer boat will not "hobby-horse" or rock up or down at every wave as much as a longer ship.
The ultimate sailboats today are the America's Cup yachts and they are design to a "box" where the parameters of length, beam, displacement, and sail area to find the "sweet spot" that makes for the fastest, lightest boat with the greatest sail area, upwind and downwind speed and pointing ability.
Quite a challenge indeed.
Keith
