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Reply | Forward Message #3268 of 6622 |
Re: OFF LIST

Seem to recall the bevel worked better than a radius because a) there was no
hydrodynamic disadvantage, b) it provided more add'l interior volume with less
material,
and c) it was a hell of a lot easier to build!

If you bend the flat panels in a developable way you get the best of both worlds
- ease
and economy of flat panels and the aesthetics of the curve.

I keep on hearing about the Kelsall "radius". Is this bagged and formed over a
tube?

Mike

--- In harryproa@..., "Robert" <cateran1949@...> wrote:
>
> -There have been a few multihull designers who reckon that a bevel
> works better than a radius. It may be worth having a 5cm radius at the
> joins to make it easier to use KSS type radius joins,
> Robert
> -- In harryproa@..., "jjtctaylor" <jtaylor412@> wrote:
> >
> > Todd,
> >
> > Yes that is a concern although none have experience on what any of
> these boats will do in
> > a problem seaway. The overhang does curve upward toward the bows
> so that is some
> > help, and terminates near the forward bulkhead. In addition it's
> elevation matches the
> > beam clearance so has some decent height. Plus I will add a modest
> flare or radius to the
> > underside just to avoid a nasty slap or thud in rough seas.
> >
> > Don't think we have any idea which way the boat face if left to
> float on it's own. Will still
> > use a chute or drogue depending on conditions off the bow/stern when
> it's really bad.
> >
> > Rob thinks it may have some benefits in normal conditions in
> reducing spray over the WW
> > hull. Think the radius should minimize the heavy slap. Have a
> suggestion on how much
> > flare/radius ?
> >
> > Regards,
> >
> > JT






Mon May 12, 2008 4:24 am

rattus32
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Message #3268 of 6622 |
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-There have been a few multihull designers who reckon that a bevel works better than a radius. It may be worth having a 5cm radius at the joins to make it...
Robert
cateran1949
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May 12, 2008
2:56 am

Seem to recall the bevel worked better than a radius because a) there was no hydrodynamic disadvantage, b) it provided more add'l interior volume with less...
rattus32
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May 12, 2008
4:24 am

-CHeck out the Kelsall website. He sets up a radius female mold with a bit of pvc pipe. It allows easy joining of panels, Robert ... there was no ... with less...
Robert
cateran1949
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May 12, 2008
9:35 am

... reducing spray over the WW ... suggestion on how much ... Nope no idea, I'm working on the small side. So my flare width is limited to material weight used...
tsstproa
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May 12, 2008
6:45 pm

Do you see a cuase for an extreme load point on beams due to the varied length hulls in certain wavelength patterens. Long hull causing WW hull to pentrate...
tsstproa
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May 12, 2008
9:03 pm

Can't see the problem of extreme load as the overhang from ww hull is so little. Significantly less racking than equivalent cat. About amount of flare: I would...
Robert
cateran1949
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May 13, 2008
5:25 am

... This reflects also my thinking. Simple facts of life: wife likes marina conveniences, marinas are full, with wife onboard I have more chances to go sailing...
Arto Hakkarainen
ahakkara
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May 13, 2008
8:33 am

Arto, One point the boss made clear, she wants to be up, not down. Part of the sail appeal is social, so wants galley in the middle, and up not down in the...
jjtctaylor
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May 13, 2008
6:40 pm

But that is the difference. In our boat I am the galley slave. I don't mind working in the galley regardless of location. And the layout I'm thinking icludes...
Arto Hakkarainen
ahakkara
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May 13, 2008
7:28 pm

-Very similar to my concepts. I feel it allows more room below for very little extra wind resistance, if any, and possibly it ends up with less spray. I don't...
Robert
cateran1949
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May 14, 2008
1:10 am

... Shuttleworth has analyzed this very much. Two articles I found first from Shuttleworth's website: http://www.john-shuttleworth.com/Dogstar50-article.html ...
Arto Hakkarainen
ahakkara
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May 14, 2008
10:10 am

A radius join built on the top edge of the bottom sheet above the bilges and a radius curve built onto the bottom of the upper section and a flat between the...
Robert
cateran1949
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May 14, 2008
12:00 pm

G'day, Need to be a little careful as quarter circle radius joins don't allow obtuse angle joins, only acute. regards, Rob...
Rob Denney
proaharry
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May 14, 2008
12:52 pm

You are quite right, but I wasn't going to restrict myself to quarter circle. Some good sheers can trim to an obtuse angle and trimming of the intermediate...
Robert
cateran1949
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May 14, 2008
2:05 pm

Rafael Francke at Cat2fold has a very interesting design for a folding catamaran that can reduce its beam while on the water. He created it along with Kurt...
Mike Crawford
jmichaelcraw...
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May 14, 2008
1:59 pm

... In ... [lot of text snipped from between] Mike, I am aware of cat2fold desing and actually thought it would be the best solution for a folding big proa. ...
Arto Hakkarainen
ahakkara
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May 15, 2008
5:21 am

G'day, Cat to fold is an interesting solution. To get 3560 degrees on the tillers, mount the rudders on the beams, although this may mess up the scissoring. ...
Rob Denney
proaharry
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May 15, 2008
5:31 am

-A simple sliding in telescoping beams is pretty simple.There is plenty of bury available. three metre wide ww hull and only narrowing by less than two metres,...
Robert
cateran1949
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May 15, 2008
7:51 am

I wanted to inquire again about opinions on the cat2fold system. In looking at the layout for my "demountable" layout, it would allow an extended beam of >...
gardnerpomper
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Aug 26, 2008
5:25 am

G'day, I have spent the last few days thinking about sliding beams and working out the best way to make them work. In the bigger boats they are definitely...
Rob Denney
proaharry
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Aug 27, 2008
1:32 pm

Rob, I was not inquiring about folding beams on the harriette, I was asking about moving the rudders away from the lee hull to midships or further. I am ...
Gardner Pomper
gardnerpomper
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Aug 27, 2008
1:55 pm

G'day, Sorry, forgot about the rudders. One bow of the little hull is folded up and glassed. A very simple operation resulting in fair curves, although the...
Rob Denney
proaharry
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Aug 27, 2008
2:06 pm

I really like any design feature that would make the boat faster, easier to set up or easier to sail. The folder sounds like it would be easier to set up...
captian_rapscallion
captian_raps...
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Aug 29, 2008
3:47 pm

Hello Rob,   With the scissors type folding system, would the Harryproa with free standing mast put more strain on hinge and sliding connection than with a...
George Kuck
chesapeake410
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Aug 27, 2008
2:43 pm

G'day, The beams on harrys are made from a box with solid carbon tow corners which take all the tension/compression loads induced by bending. If the tow is...
Rob Denney
proaharry
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Aug 27, 2008
2:55 pm

I was playing with the idea a while back and worked on the vertical component taken by I beams connected with a decent pin in the center, with the fore aft...
Robert
cateran1949
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Aug 28, 2008
9:17 am

I can see the problems of the sliding beams being high friction if there is any load on the beams. Reducing the load may be possible by unweighting with a...
Robert
cateran1949
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Aug 28, 2008
9:41 am

Hello,   I do not think the load should be vary much when not under sail and in calm water which is when you would be reducing beam.  A friction pad or...
George Kuck
chesapeake410
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Aug 28, 2008
12:53 pm

-I like the idea of a gear drive for keeping them in parallel. There would be quite a few hundred kg on the friction surface, even in shallow water as the ww...
Robert
cateran1949
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Aug 28, 2008
3:30 pm

G'Day, Just uploaded a picture of a scheme that does not use 2 part beams. Each end of the beams are in large bearings. Leeward ones are mounted on the side...
Rob Denney
proaharry
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Aug 28, 2008
3:49 pm
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