speed vs. stability

[Ken Cobb]

As a result of a discussion on seaworthiness of boats on the "ask all sailors" board at this site, I was directed to some technical articles about the topic. The two indicators that seem to come up a lot are the length to displacement formula and the capsize risk formula. To summarize both, boats that are heavier for their length, and narrower in the beam, come out the best on both formulas.My point for Beneteau owners is this: The 361 and 393 come out worse in those formulas than the comparably sized Hunters and Catalinas, basically because the Beneteaus don't have as much displacement for their size. This should make Beneteaus the fastest cruisers around, but it also suggests that the 361 and 393 should not be taken on blue water passages. Thoughts or comments?

 

[Henry]

not that simple

While your general assumption may be valid in many cases I don't believe it applies across the board. Hull shape and keel depth work to resist knockdown and hopefully to return the boat to vertical after. Many older boats were narrow and heavy but did not necessarily have much keel depth. These boats tend to heel more without threatening stability. Wider newer designs tend to have more initial stability. The self righting ability will be determined from hull shape, keel depth, keel weight, and weight of mast and rigging. I suspect that many new lighter designs with fin keels would return to vertical a lot faster than some of the old shallow long keel designs. I don't think there are any simple answers here.

 

[Rick McGlone]

Formulas are just a guide

I have done alot of reading regarding capsize potential and stability and it seems the one thing that people overlook most often is that boat designs have changed over the years and fin/bulb keel boats do in some cases have a lower center of gravity than full length keel boats. If you only use displacemnet and length /or beam measurements, you can't possibly have enough information to reach an accurate assessment.You would have to know mast height / weight and the amount of superstructure above the waterline. So the formulas are far to general to be a hard and fast indicator of a boats abilities. Just one guy's opinion.

 

[Capn' Nemo]

Bottled Beer increases Displacement

just add Three cases of Red Stripe and and four cases of Carona. increase size of liquer cabinet