Join Date: Feb 2000
Location: Annapolis, Md
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For the record, the capsize screen factor and the motion comfort index tell you next t nothing about the likelihood that a boat is going to capsize or have a comfortable motion. Both of these formulas were developed at a time when boats were a lot more similar to each other than they are today. These formulas have limited utility in comparing boats other than boats which are otherwise are extremely similar.
To explain, neither formula contains almost any of the real factors that control motion comfort or seaworthiness. Neither formula contains such factors as the vertical center of gravity or buoyancy, neither contains weight distribution or buoyancy distribution, and neither contains any data on dampening all of which really are the major factors that control motion comfort or likelihood of capsize. Weight alone has next to no bearing on motion comfort and stability.
I typically give this example to explain just how useless and dangerously misleading these formulas can be. If we had two boats that were virtually identical except that one had a 500 pound weight at the top of the mast. (Yes, I know that no one would install a 500 lb weight at the top of the mast but, for example, heavy decks, spars, shallow draft, low density ballasting etc, can easily have that kind of impact.) The boat with the weight up its mast would appear to be less prone to capsize under the capsize screen formula, and would appear to be more comfortable under the Motion Comfort ratio. Nothing would be further than the truth. That is why I see these formulas as being worse than useless.
Last edited by Jeff_H; 09-03-2006 at 12:58 AM.