I've been using Mitchlet/Godzilla for some time, primarily for multiman racing canoes (the Texas Voyageur just finished first in Yukon River Quest...again) on to proa content. I just recently started analyzing short flat panel constrained hulls and agree there's some interesting preliminary results, time will tell.

At 90 kilos design displacement your boat must be ultra light plus a fairly lightweight paaload.

cheers,
Skip

>
> Todd
> That boat was a product of GODZILLA. A hull optimising routine that 
> runs with Michlet. There are some details here:
> http://www.cyberiad.net/leo.htm
> I constrained it to produce a near flat bottom because I wanted to 
> build in flat panel. The drag was predicted to be a little more than 
> my V11 round section hull but it ended up being slightly less - some 
> due to lighter weight from method of building in flat panel; some due 
> to shorter length.
> 
> I have been using GODZILLA on Michlet for producing hull shapes since 
> 2005. It gives very reliable results. It is based on thin ship 
> theory to determine wave drag so is purely analytical for the wave 
> component of drag. Hence it gives good results for quite odd shapes 
> as long as the L/B is no less than about 5. I have seen results for 
> L/B of 4.5 that were reasonable.
> 
> Leo has now produced software called Flotilla that iterates the trim 
> so it can determine how the hull will trim at various speeds. He is 
> using this software for the hull component of the work he is doing 
> with the AIS on rowing shells. He has not yet got to flat panels on 
> rowing shells but you never know.
> 
> It takes about 5 minutes to show the real difference between flat and 
> round sections for a given displacement and design speed. It is much 
> less than the common wisdom based on comparing the perimeter for 
> enclosed area of a rectangular section versus a semi-circular section.
> 
> Rick W
> On 03/07/2010, at 11:43 AM, tsstproa wrote:
> 
> > SWEEEEEEEEEEEAT BOAT LONG AND SLEEK. The lines look almost unreal 
> > there so straight/sharp. Very nice work.
> >
> > But at what displacament, waterline levels, and under water plane 
> > area are you working with?
> >
> > Todd
> >
> > --- In harryproa@yahoogroups.com.au, Rick Willoughby <rickwill@> 
> > wrote:
> > >
> > > Problem with a large proa is you are not going to shift a large
> > > amount of weight each time you shunt.
> > >
> > > This link shows the hull I have tested:
> > > http://www.rickwill.bigpondhosting.com/V14.htm
> > > It had lower drag at higher speed than initially predicted in level
> > > trim because it lifts due to wave pressure. There is now software
> > > available that allows the trim and resulting drag to be calculated.
> > > The highest speed I have pushed it to is 9kts and this is below the
> > > point where dynamic lift is significant. The trim change is due to
> > > pressure variation on the hull from wave making and is noticeable
> > > from about 5kts.
> > >
> > > The simple wetted surface argument for a round section hull is not
> > > valid once wave drag comes into the equation. There is very little
> > > difference in drag between round sections and flat sections but the
> > > flat sections will lift more and trim more bow up. This should be an
> > > advantage on a large proa where the weight distribution cannot be
> > > easily adjusted.
> > >
> > > Rick
> > >
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