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[email protected] dougking888@yahoo.com is offline
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First recorded activity by BoatBanter: Feb 2007
Posts: 900
Default Roll Pitch & Comfort

tsmw wrote:
C = D/(.65(.7Lwl+.3Loa)*B^1.33

Where C is the "Comfort Ratio", D is displacement, Lwl is the length
on the load waterline, Loa is the overall length and B is the beam.

Now, if you fix the displacement but make the boat bigger in any
dimension the ratio goes down. All of the dimensions are in the
denominator. Thus, it seems to me that making the boat "bigger" makes
it score less well on the CR. I don't follow how you can say that if
you increase the LOA but not LWL the ratio goes up. Are we looking at
the same formula?

-- Tom.


Try it in excel. I think the multiplier of less than one has an
effect.
If you keep everything else constant and increase the LOA, the "Motion
Comfort Ratio" goes up slightly.
That's making the boat bigger, nyet?
If you keep everything else constant and decrease the LWL, the "Motion
Comfort Ratio" goes up by a greater amount than above. Ditto for
decrease in Beam. This isn't increasing size, but decreasing LWL while
holding everything else constant is increasing the overhangs, which
does not really improve seakindliness.
The greatest increase in the ratio is of course had by increasing
Displacement, which is again increasing size.
Disp & LOA are the largest factors in a boats size IMHO

DSK