Join Date: Oct 2006
Location: on the boat - Chesapeake
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Re: knockdown vs. capsize vs. broach
A knockdown refers to the rapid change in heel angle from a acceptable, normal heel angle to something beyind that point.
A broach refers to a rapid change in direction (yaw) that will usually lead to increased heel or perhaps a knockdown, but nothing in the definition of a broach requires either to occur.
A capsize is heeling to the point where stability switches from positive stability (trying to turn upright) to negative stability(the point at which the boat no longer tries to right itself.)
Saillife and Jeff_H have a pretty good grip on the definitions as used in the naval architecture community.
A knockdown is the boat going over. There is no deterministic definition that I am aware of but if the boom end goes in the water I think you are getting there.
Capsize is upside down. You may or may not come up, and if you come up the direction of rotation is not clear.
Broaching is a description of a dynamic event that is associated with a substantial loss of directional control (almost always rounding up) and substantial heel.
You can suffer a knockdown without broaching, and can broach without being knocked down. You can be knocked down during a broach.
They all suck.
sail fast and eat well, dave
beware "cut and paste" sailors.
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Last edited by SVAuspicious; 08-08-2014 at 11:17 AM.