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Old 09-27-2012
bobperry bobperry is offline
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Re: Moment curves

Uh Oh, those are not my weights. I own a huge collection of various shapes and flavors of spline weights but they are not pretty and they are spread all over my office as paper weights. Sigh. They are however very well worn. When you see pretty painted weights like that you can assume they are sitting unused far too much. Mine have the paint worn off. I never want to know how much lead is in my body. Might explain a few things.

I agree with Jeff's guess as to the nature of the curves. However, given the long and skinny shapes in that day I doubt very much that the heeled trim changed much at all if at all. Sail a 6 meter or even an Etchels or a Soling. There is little perceptable trim chage when heeled. I don;t know what the rest of this boat lookled like but I'm going to asume it was relatively narrow with overhangs and a short DWL. The ends are probably damn near symetrical and close to the same volume. The change in fore and aft trim would have been at the most minimal. Of course due to the bow having a point and the stern having a transom there is more volume aft so naturally the boat when heeled will go slightly bow down. But I don't see anything in those curves to tell me how much bow down. Still that doesn't stop a guy with a lot of time on his hands from doing the calculations needed to lay out the curves. But had the curves been productive in terns of design efficiency and effectiveness I suspect we would have seen them popping up on oither designer's works.

Now, if other designers had been using the same moment curves you could do a "I'll show you mine if you show me yours" thing and that might have value. But I think in order to evaluate numbers you need benchmarks of known performance that used the exact same variables measured in the exact same way.

I think I'll stick with the answer "It's BS". But fun BS and if it really worked for this designer then good for him. What's his name again?

Bob the snide
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Last edited by bobperry; 09-27-2012 at 01:26 PM.
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