Bridgedeck centreboard why don't they work???

But if you add those 'solid' side supports you will interfere with a lot of water/wave action passing under the bridge deck. That is why I wanted to accomplish it with wire or one of the newer synthetic rigging materials of very small cross-section

 

only if the pivot is very low
my idea is to have the pivot some 65-70 cm above the waterline
the support arms are covered by the nacelle

 

Its not so much where the pivot point is, but rather the athwarship staying you can provide for this long canterlivered board. I want to provide for as favorable situation as possible...ie, look at these favorable angles, and low attachment points, but still above the waterline to create as little drag as possible....




I've personally experienced (and learned) from what the 27' Stilettos experienced.

 

Brian; if your going to use 2 boards, why not use a chamfer panel between hull and wet deck and incorporate a board in each side ? No nacelle required.

 

The point was it would also be structural spar.

 

That's correct. That was the primary purpose of the nacelle. It was only afterwards I thought about hanging the board(s) there.
PS: Not exactly, I really gave thought to this idea concurrently, particularly when I recalled my past association with Stilettos

 

Kelsall's Tonga Tini

Found a couple of interesting photos on this 'for sale site' for Tonga Tini's central board (not centerboard)

http://www.xboat.uk/318-DEREK+KELSALL+CATAMARAN+TONGA+TINI.html

Hope you can access them,...interesting (hope they stay up online for awhile)

It appears as though this is some sort of central daggerboard that may be able to be tilted fore-to-aft to some degree?
Interesting the staying of his 'central pod/nacelle'

 

Cat's Meow

How about a LARGER version of that daggerboard arrangement. Here is Kelsall's 78 footer with a central daggerboard, and a central rudder,..in a full length nacelle.
http://www.sailtrekker.com/
Not sure why the website is titled Sail Trekker when the boat's name is "Cat's Meow".

This vessel has been thru St Augustine a few times recently, and I got a tour onboard on one occasion. I specifically wanted to ask the captain/owner about the effectiveness of this board arrangement. Unfortunately it appears as though the captain and his wife have a little trouble handling this size vessel on their own, and thus seldom sail it under full sail from what I understand,...and thus find no need to utilize that big board. She does have quite a BIG rig.

 

for Brian

arrows adjusted

 

Here are some centerboard pictures of my homebuilt catamaran

https://files.fm/u/k7cs3qcw

 

many thanks, the photos are great as is your inventiveness. How is the wind where you sail? Reliable and useful I hope.

 

Mulkari, thank you very much for your contribution to these discussions. Your solution appears to relatively simple, particularly for smaller craft.

I want to select a few of the photos to post directly, in case something should ever happen to that link.

 

Kelsall 34 catamaran

...from another forum comes another personal experience endorsement of the idea..

 

ummm, "To summarise my view, if I was building or designing a new boat it's probably not a system I would choose "
Even though his last boat had a daggerboard - and thus problems with fouling, drag, lack of kickup, potential for hull damage/leaks.
Thanks Brian, could you send me a link to the forum?

 

I wonder about that statement as well UpOnStands,...will have to dig deeper into it. I did send him a note to please come visit the discussions here.

Not so sure I can send you a usable link, as it is another type of forum that I believe you must join to get access. It is called "multihulls@steamradio.com"
Ben Mo <b.monypenny@gmail.com> via steamradio.com
reply-to: Informed discussion of multihull issues <multihulls@steamradio.com>