Center nacelles and wave pounding in cats.

[Doug Lord]

Originally Posted by rapscallion

Here is an interesting catamaran design...

http://www.wellscoates.org/inventions.htm

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Pretty cool stuff ,Raps-thanks!

[brian eiland]

Originally Posted by rapscallion

Here is an interesting catamaran design...
http://www.wellscoates.org/inventions.htm

Perhaps you might have placed that posting over on a mast, or sail, or wingmast related discussion?...probably better response?
...maybe here?
sail aerodynamics

Wing-drive

homebuilt wing mast

I just don't see where it relates to wingdeck slamming?

[Doug Lord]

Originally Posted by brian eiland

Perhaps you might have placed that posting over on a mast, or sail, or wingmast related discussion?...probably better response?
I just don't see where it relates to wingdeck slamming?

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Brian, the raised center nacelle on Coates cat seems relevant to the discussion to me.......Maybe you were thinking of post #60?

[Boston]

what if the center nacelle is able to move virticaly, so when its smooth you can ride on the outside sponsons and when its rough you can dip the center nacelle to be in contact with the water. The drag issues are not the primary concern in a high seas scenario and by dipping the center nacelle your eliminating a lot of pounding and lowering the CG. All you'd need is some hydraulics and the connecting arms could be the only real moving part.

just an idear
cheers
B

[rapscallion]

Originally Posted by Doug Lord

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Brian, the raised center nacelle on Coates cat seems relevant to the discussion to me.......Maybe you were thinking of post #60?

Righto Doug!

The boat reminds me of strings, the new gougeon catamaran.

[geodude]

Hi all.

I'm new to the forum but bare with me.

It seems from what I read that a "square" 40ft cat should ideally be greater than 0.9m clearance, and the bridgedeck should be a short as possible.

But that would mean a total superstructure height to LOA ratio of around 1:4 if you want to have full standing headroom in the bridge. That is a seriously boxy boat, and what about the effect of all that windage in heavy weather scenarios.

Surely the bridgedeck need not be that high across its entire length. Couldn't it step down to 0.7m or even less at the saloon/cockpit bulkhead while retaining a minimum of 0.9-1m clearance elsewhere. Afterall, the most vulnerable areas for slamming are those nearest the ends of the craft. By the time a wave gets to the middle of the bridgedeck wont the boat have risen somewhat to the wave? That would get the superstructure height down to a more reasonable 2.5m on a 12-13m LOA while retaining a high bridgedeck over 90% of the bridgedecks surface. Also wouldn't breaking up the flat surface, or even giving the bridgedeck positive curvature fore and aft, strengthen the deck whilst reducing the area that slams at any particular time. Particularly the latter seems like a sensible way of of reducing slap as no matter how the wave hits the deck, its curvature would deminish the force of the blow.