Den lørdag 13. juni 2015 skrev Bendik Vignes <bendik.vignes@gmail.com> følgende:
Thanks for your answers guys!From what you write, it seems to me that there is an advantage with a true displacement hull compared to a semi hull (or a modified displacement hull) regarding power demand at low speeds.Then I might keep my Risør 27 - which certainly is a true displacement;-)Regards Bendik
Den onsdag 10. juni 2015 skrev 'cal' h20dragon@centurytel.net [electricboats] <electricboats@yahoogroups.com> følgende:
Absolutely, that is a good thing on any hull with double ends, even if the main stern section is fatter to provide less "squat" powering up. Also helps the stern stay level with wave action, like a shock absorber somewhat. Looks like a Dutch "botter" design influence to the design, very cool an better looking, with the stern protection that gives. Smaller cockpit, but worth it in my opinion.Try to find data on the shape, may be a factory part added to all or later models of that hull shape. I have modified some of my designs later, after water trials and test time to make them work better.Good Luck, CalFSent: Wednesday, June 10, 2015 5:54 AMSubject: [Electric Boats] Re: Displacement vs semi-dispalcement hull at low speeds
I suspect it was added so that the stern would not squat as much at higher speeds.
It's not just a matter of displacement vs. planning (the term 'semi-displacement'
is a figment of marketing imagination), it's also about how easily a hull is driven through the water.A true displacement powerboat doesn't need much power to attain moderate speed. By way of example, my 36' Gulfstar trawler will do 8.2 knots. with only one of it's 80hp diesel engines, while dragging the other's 17"prop. A friends 34' Marine Trader (semi-displacement) won't come close to that with it's single 120hp diesel.eric SV MeanderI have a lot of experience with semi displacement larger powerboats.
viewing the boat it seem that it is a true displacement hull with a aft projection stuck on the hull. if it can be removed you will have a true displacement hull. Try it like it is then if you see eddies and wave making at the stern at 4.5 knots remove it.
It was added after the hull was made because it would be impossible to mold it with the hull.
mike
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Posted by: Bendik Vignes <bendik.vignes@yahoo.com>
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