Over the past several months, I have been Very actively looking for my ideal boat. I have concrete plans for what I intend to do with her and I have a pretty good idea of the size and type of boat I want and need.
Seaworthiness is one of the major features my boat must have. And with that, the question arises, what is a seaworthy
I read various things about keel
weight and types - full, modified full, fin, etc. And I have read various things about displacement
, narrow beam vs wide beam, sail area in relation to displacement
, blah, blah, blah.
What the heck does all that mean? Is my boat going to be tender
or stiff? Is the boat going to get knocked down by a 20 foot wave or 50 knot wind
? Will my boat capsize
with the same 20 foot wave or 50 knot wind
? And more importantly, will it right itself and how quickly?
I found this great site that offers formulas for everything from hull speed
screening to angle of vanishing stability.
Sailboat Design and Stability
With all that, I have laid out a few MINIMUM
characteristics my boat Must have. For one, I want a ballast to displacement ratio of at least 35% but would prefer something closer to 40.
But, looking at different boats, this factor seems not to apply. For example, if you look at Beneteau
boats, you will find they have light displacement and very poor % for ballast. I looked at the Beneteau Oceanis
323 and discovered the displacement is around 9350 with a ballast around 1550. That calculates to a 29% ratio. Unacceptable by any formula but I know these boats have crossed oceans, even the 32 footer.
On the other hand, a Com-Pac 27 is light, 6000 lbs with a 2500 pound ballast which calculates to a 41% ratio. Does that mean you would cross an ocean with a Com-Pac 27?
What does all this mean? I believe every and any boat can get knocked down and unfortunately every and any boat can get capsized. But, which ones will right themselves quickly, if at all?
Are there any engineers, boat designers, people in the know that have a clue as to what all these formulas and calculations translate to in a practical sense?