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Re: S&G: Design basics rules of thumb *LINK*
By:Dave Houser
Date: 12/11/2003, 4:07 pm
In Response To: S&G: Design basics rules of thumb (Jim Wesley)

: I've been playing with the hull program from Carlson Design to see if I can
: create a multi-chined hull. I'm not sure where to try to locate the center
: of buoyancy or center of lateral resistance in relation to each other or
: the loa in order to have reasonable handling characterictics. There's
: nothing special about the hull shape, a little beamy maybe at 16.5 feet by
: 25-26 inches, just looking to avoid something obnoxious. Thanks any
: insights.

I went through the same thought process some time a go. After drawing free body diagrams of lateral forces I concluded that the center of lateral resistance of the water should be directly under the center of lateral resistance of crosswinds i.e. the centroid of the lateral area below the waterline should be directly under the centroid of the lateral area above the waterline. This assumes the lateral forces of the water and air over a three dimensional object will center on the area centroids creating equal and opposite moments about the CG (or center of buoyancy) and ignores any affect of forward motion. If the two foces line up it doesn't matter where the COB is located. My guess is it will be close enough that moving the seat forward or back an inch will trim the boat to correct for the error. This only looks at crossiwnds, quartering waves is a whole different topic. I guess that is why they build proto types. You just can't calculate everything and change are needed to correct for assumptions and oversights.

For more rambling click on my "Old Post" below.

Messages In This Thread

S&G: Design basics rules of thumb
Jim Wesley -- 12/10/2003, 7:54 am
Re: S&G: Design basics rules of thumb *LINK*
Dave Houser -- 12/11/2003, 4:07 pm
Re: S&G: Design basics rules of thumb
Jim Wesley -- 12/11/2003, 6:24 pm
Re: S&G: Design basics rules of thumb *LINK*
srchr/gerald -- 12/10/2003, 10:32 am