design a beach / lagoon proa

What does your design brief look like? What are your requirements for the boat? What do you want to use it for? What does your budget look like?
jpn
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Joined: 28 Dec 2015, 15:28

Re: design a beach / lagoon proa

Post by jpn » 07 Jan 2016, 07:57

Rob "keep it simple and enjoy", yes, and perhaps the most extreme solutions are only efficient in narrow bands of operating conditions.

re the chop and planing hulls: even on the narrow lagoon that i described the chop is quite steep and close spaced " water like concrete building blocks".
If i mention Jzerro as a ref it is mainly because I remember the thrill of cutting through water fast on an early Hobie after bouncing on small planing dinghies. I continue to question myself on this choice, on what could be personal and aesthetic grounds rather than anything to do with speed or ultimate efficiency. I am an armchair sailor, and so i refer to these few experiences over the years in making choices now. I remember being taken for a sail on a small ( about 27ft) Piver Tri , not a bad boat, not one of the floating castles , and seeing how much water was displaced by the lee float. So there is some kind of trade off in my argument , I don't want a hull that is deep and narrow, but I don't want it to jump around a lot.
I also remember , as amongst my top experiences on boats: sitting inside a heavy wooden clinker dinghy, and ghosting in light wind, the sound of the water lapping on the strakes; and lying forward on the Hobie tramp, with my head and shoulders in front of the crossbeam, lifting the sterns, running in medium light wind in a deeper channel in a lagoon, surrounded by miles of shallows, following the changes in colour of the water, the boat just gliding almost silently. So it wont always be about speed and wind and adrenaline
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Rob Zabukovec
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Joined: 27 Aug 2014, 21:20

Re: design a beach / lagoon proa

Post by Rob Zabukovec » 07 Jan 2016, 13:23

jpn wrote: ....re the chop and planing hulls: even on the narrow lagoon that i described the chop is quite steep and close spaced " water like concrete building blocks".
If i mention Jzerro as a ref it is mainly because I remember the thrill of cutting through water fast on an early Hobie after bouncing on small planing dinghies. I continue to question myself on this choice, on what could be personal and aesthetic grounds rather than anything to do with speed or ultimate efficiency. I am an armchair sailor, and so i refer to these few experiences over the years in making choices now. I remember being taken for a sail on a small ( about 27ft) Piver Tri , not a bad boat, not one of the floating castles , and seeing how much water was displaced by the lee float. So there is some kind of trade off in my argument , I don't want a hull that is deep and narrow, but I don't want it to jump around a lot......
The flat bottoms on the hulls are so narrow, you won't be bouncing around a lot......there are at least three classes of flat bottomed cats in Australia which have been around for decades...look up the Arrow and Arafura Cadet. My fastest speed, 23 knots confirmed by a speedboat alongside, was on a 20ft Attunga cat which was also a planer....
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Skip
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Joined: 31 Aug 2014, 16:40

Re: design a beach / lagoon proa

Post by Skip » 07 Jan 2016, 16:45

John wrote:
Skip wrote:... Re the speed thing, I hit just over 20 mph (17+ knots) once in P52 and would just as soon not repeat the experience. I hope to spend days on Nomad cruising at 10-12 knots, plenty fast for an old man like me (the combined age of the Texas 200 crew, both of us, will be 149 years).
Skip,

That is impressive! Could you describe how the hull felt going at that speed?

-John-
Terrifying, pretty much leaping from crest to crest (albeit smoothly :D ). This was with a 35 s.f. +/- polytarp sail on a broken mast being steered, barely, by a 12' oar.

http://www.texas200.com/2009/stories/johnson/index.htm

Skip
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Amati
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Joined: 06 Nov 2014, 02:16

Re: design a beach / lagoon proa

Post by Amati » 07 Jan 2016, 16:57

jpn wrote:Rob "keep it simple and enjoy", yes, and perhaps the most extreme solutions are only efficient in narrow bands of operating conditions.

re the chop and planing hulls: even on the narrow lagoon that i described the chop is quite steep and close spaced " water like concrete building blocks".
If i mention Jzerro as a ref it is mainly because I remember the thrill of cutting through water fast on an early Hobie after bouncing on small planing dinghies. I continue to question myself on this choice, on what could be personal and aesthetic grounds rather than anything to do with speed or ultimate efficiency. I am an armchair sailor, and so i refer to these few experiences over the years in making choices now. I remember being taken for a sail on a small ( about 27ft) Piver Tri , not a bad boat, not one of the floating castles , and seeing how much water was displaced by the lee float. So there is some kind of trade off in my argument , I don't want a hull that is deep and narrow, but I don't want it to jump around a lot.
I also remember , as amongst my top experiences on boats: sitting inside a heavy wooden clinker dinghy, and ghosting in light wind, the sound of the water lapping on the strakes; and lying forward on the Hobie tramp, with my head and shoulders in front of the crossbeam, lifting the sterns, running in medium light wind in a deeper channel in a lagoon, surrounded by miles of shallows, following the changes in colour of the water, the boat just gliding almost silently. So it wont always be about speed and wind and adrenaline
8-)

This is why I really dug D 2 boards, and the Serenity (above). And why Amati is a light air flyer, mainly, although she is pretty effortless in the heavier stuff, at least downwind. But I continue to fine out the sailplan to less drag (that is less standing sail area) and add drifters etc in the light stuff when they're easier to handle. I told Mr Perry, when we had her designed, that I wanted effortless performance, like the older Jaguars.

It seems to me, though, that of all the sailing craft out there, proas must be capable of the most automatic handling.

But I'm 63, so maybe that's part of it?
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Amati
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Re: design a beach / lagoon proa

Post by Amati » 07 Jan 2016, 17:15

Try googling 'class b sailing canoes', and take a peek at the images. It's almost an underground movement.
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Amati
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Re: design a beach / lagoon proa

Post by Amati » 07 Jan 2016, 19:42

Here's something else that might get some synapses firing

http://www.outsideconnection.com/gallant/kayak/

He turned a kayak into a light air windsurfer :!:
John
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Joined: 05 Aug 2015, 05:57

Re: design a beach / lagoon proa

Post by John » 07 Jan 2016, 21:39

Amati,

Thanks! that is a great little project. From elsewhere on the same page, a small trimaran made from plywood...

http://www.outsideconnection.com/gallant/bluetri/

I especially like his use of ladders for cross beams...

He later ditches the 14' Hobie amas and makes his own after running into the the trimaran problem of sinking his leeward ama: http://www.outsideconnection.com/gallan ... rofit2013/

jpn, I think your boat would be 1/4 of the work. No beach camping amenities. Smaller cross-section main hull. Smaller ama. Only one ama.

-John-
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Rob Zabukovec
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Joined: 27 Aug 2014, 21:20

Re: design a beach / lagoon proa

Post by Rob Zabukovec » 07 Jan 2016, 23:57

John,

Thanks for he link....Best Guess trimaran is very interesting.....an excellent base point for jpn's project.

Flat bottoms waterskiing and planing......plus electric propulsion!!!!!!!!

Rob
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tdem
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Re: design a beach / lagoon proa

Post by tdem » 08 Jan 2016, 03:29

My flat bottom proa is a pretty smooth ride. I had it out on new years day in some rough waves, video coming soon ;-)

The other option is of course almost square mid section with slight deadrise, going to a sharper v in the bows. Ron Given does this well, like on the Paper Tiger catamaran.

Here is a good comparison of some options for mid section. http://www.rclandsailing.com/catamaran/design.html The pure triangle is so bad, you almost have to make it in several sections or with curvature, which makes things more complicated. In theory. In practice I've been on a tiki 26 in a blow, and at no point was I thinking, "wow we could go 5% faster with a more optimal hull shape".
The most important thing is to keep the most important thing the most important thing.- Donald Coduto
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Rob Zabukovec
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Re: design a beach / lagoon proa

Post by Rob Zabukovec » 08 Jan 2016, 20:20

tdem wrote: The other option is of course almost square mid section with slight deadrise, going to a sharper v in the bows. Ron Given does this well, like on the Paper Tiger catamaran......
You could, but it is the flat under the bow which helps keep the nose out,avoiding going down the mine.....just look at AC and Groupama C class cats. ....flat ellipse midsection going to flat in the bow. Look also at the Flat Bottom Girls thread....it is the reverse of what you would expect.
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