Join Date: Feb 2000
Location: Annapolis, Md
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Re: displacement/ballast ratio
In and of itself, the displacement to ballast ratio only gives you one small portion of the story. It really is not all that useful without knowing the vertical center of gravity of that ballast, and the beam of the boat. For example, a deep draft boat with a smaller D/Bal say, around 33% but which employed a high density in a bulb, would inherrently be more stable than a shallow draft boat with a much higher ballast ratio but in the form of a low density ballast carried in the bilge or an encapsulation envelope.
Similarly, a very narrow boat with a very high ballast ratio carried very low, might not have as much stability as a more moderate beam boat with the same ballast ratio or even with a lower ballast ratio.
In other words, boats act as a system. While a boat's statistics and ratios may provide helpful information, they cannot provide a comprehensive picture of the behavior of the boat as a whole. For that reason, modern designs which are often lighter and have smaller ballast rations than more traditional designs may in fact have significantly higher stability (relative to their displacement and drag) across a broad range of heel angles.
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Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay
Last edited by Jeff_H; 01-20-2014 at 12:45 PM.