What that thread does not discuss is flare. The least wetted surface 3-panel hull has a side flare of 28 degrees off vertical. For a given volume this results in about 5% more wetted surface than a semi-circular section.
When the 32 function version of Michlet is constrained to hard chine it produces a shape with variable flare. The ends have greater flare than the middle. That gives more volume for a given length and maximum beam or less length and less maximum bean for a given displacement.
A hull for minimum drag at a given speed and displacement will be shorter if it has a hard chine than a semi-circular section. That means the hull alone will be lighter. For a racing boat that weight saving will give an overall performance benefit.
On sailing boats the benefit of the flat bottom is mainly from hydrodynamic lift as speed increases. With sailing, longer hulls are beneficial because they suffer less from pitching.
The amas on modern non-foiling tris are close to optimum shape for high speed sailing:
The curved foil would support some of the weight but the ama is a high speed displacement hull. Almost flat bottom aft with flared transom and less flare in the mid section. The sides at the bow flare inward to improve wave piercing.
Rick
On 13 Mar 2019, at 3:00 am, eruttan@yahoo.com [harryproa] <harryproa@yahoogroups.com.au> wrote:Didnt know where to put this. I find boatdesign too irritating to use, so i just browse occasionally.
https://www.boatdesign.net/threads/canoe-with-square-bottom-hull-vs-rounded-hull.61808/
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Posted by: Rick Willoughby <rickwill@bigpond.net.au>
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