If you are using the 32 parameter shape function in GODZILLA to generate hull shapes then you will naturally get the harder chine for the lowest drag hull at high speed to length. It also forms a transom.
Linked hull lines has a design speed of 4m/s for 100kg displacement:
It is not directly from GODZILLA but close to what was produced. Rather than working with a high density mesh I just import the lines and then adjust a box to best fit those lines.
It is interesting to watch how a shape evolves as you increase the design speed for a given displacement. GODZILLA is a very powerful program in terms of what it teaches about hull shapes and drag.
I also have my own hull motion program that is very good for analysing clearance of superstructure and what reserve buoyancy does to pitching and pitchpole prevention. Clearance is a little appreciated performance factor in multihulls.
On 1 Jun 2018, at 8:55 pm, Björn bjornmail@gmail.com [harryproa] <harryproa@yahoogroups.com..au> wrote:Thanks Rick,Lazy of me to not double check my numbers. Your are completely right. The ratio between square and round is sqrt(4/pi) (not 4/pi), which is a difference of 13%, and aligns with your numbers above. (Without perfect ratios in the rectangle, the difference was probably 15% in Michlet, which is the number I had remembered.)Interesting that the flare makes such a difference, but it makes sense! Thanks again, and sorry to everyone for posting the wrong numbers.So with some rounded corners of the flared hull, the difference is even less than 5% - nice!
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Posted by: Rick Willoughby <rickwill@bigpond.net.au>
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