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post #1101 of Old 07-12-2013
bobperry
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Re: Bob Perry's take on Wolfenzee's dream boat

Out:
We don't have "bads" here. It's always a good day when you learn something. I almost always learn something when I try to formulate answers to questions. I think chines work on high performance boats because they help keep the buttocks flat and push volume outboard where it provides stability gains. On lesser perormance boats chines can push volume aft and low eher it can be used for acomodations. i.e. quarter berth width.

I think narrow is always faster upwind or down. That's where a good part of the magic is in the big AC cats. The downside to narrow i a monohull is the form stability loss and this has to compensated for with deep draft and a low VCG.

A good indication for how much a boat is going to squat is the curvature of the rocker.
Sometimes this is called "buttock slope". Heavy boats have more rocker, high angle of buttock slope, for a given DWL. ULDB's have very little rocker, low angle of buttock slope and therefore very flat buttocks. They don't pull up a big stern wave.

If you were to se a Little Harbor model motoring alongside a similar DWL ULDB you would see a big stern wave on the Little Harbor and almost no stern wave on the ULDB.

Please visit my blog. It's fun to read.


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Bob's Blog ....

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Please also visit my new web site
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