Bridgedeck centreboard why don't they work???

Now imagine if some of that solid structure of the 'spine' was instead just built of composite rigging materials (spectra and struts) like the Alinghi vessel pictured above (instead of my professed continuous flat plate).

And only in the area of the pivoting boards was the sold flat plate employed between the bottom rigging 'wires' and the underside of the deck panel.

 

http://www.serenityshipyard.com/en/shambala-55.html

Trying to find out more about this design,...curious :?:

PS: (these are the same fellows who did some engineering on the foiling Gunboat,....Schickler Tagliapietra served in a support role in the development of the boat, as a new member of the DNA design team)

PS: (the shipyard is one I know of in Thailand,...real good work)

 

I was trying to reorganize my laptop the other day and ran across this illustration I had made with two different CB arrangements

 

this seems to be the most likely approach
the purple indicates the axis of a hydraulic rotary vane actuator mounted on the swing axis formed by the solid stays. They share the mounting pin embedded in the board around which the board can pivot.

 

Is this pure supposition? ...or some inside knowledge??
I believe we should let them answer as to their own design.

If you have an alternative to the idea, then perhaps it should be presented in that manner.

 

Having said that I am trying to interpret your posting and co-ordinate the drawing with the words. Where is the board?

And the purple thing is the pump?....purple indicates the axis of a hydraulic rotary vane pump.

And how is this mounted in the vessel?

Sorry maybe its my imagination not co-coordinating with yours.

 

Here is one of their photos - my annotations
the second shows the outboard end of one of the stays -- the carrier is bolted to the bottom of the bridgedeck -- there are 3 carriers, 2 for the stays and the center one for the actuator.

 

Please excuse me UpOnStands, I had not realized this earlier posting was the same vessel.
http://www.boatdesign.net/forums/multihulls/bridgedeck-centreboard-why-dont-they-work-57051-9.html#post796813

I got the impression from that first posting that the vessel in question was not built, and that it was an owner builder project he had in mind, not a professional shipyard construction. And I completed missed that they were the same name vessels,...old age eyesight or something...

 

Small inflatable centerboard cat
https://youtu.be/gOAlKh_oXQo

 

UponStands you have exactly the solution that I had in mind. For the only exeption that I would like to have my bridgedeck shape like V-hull underneath to hide all the cebterboard into it and and also to soften the wave slapping under the bridgedeck.

 

small cat

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Thats a pretty cool little cat! Also "speaks" to the blunt bow vs a thin bow.
Thanks for the vid!

 

that idea runs the risk of the board damaging the nacelle if the board was angled when it was pushed back and up. You would be better off putting trim tabs on the board but I'm am not sure there is definite proof that such complexity is needed for a cruising catamaran. You ready to pay for a custom engineering job?
this is the simpler one -
#1 15 degree forward rake to change center of lateral resistance and reduce cavitation,
#3 stowed
the red translucent blocks provide the load/bearing support needed so you can eliminate the stays.

 

A few modifications to your suggestion that I might suggest for this arrangement.
1) You don't really need a 15 degree forward angle. It appears as though 3 to 5 degrees prevents most of the 'ventilation'
2) The top of the board needs to have a shape that can bear upon, some sort of 'stopping block' to 'guide' the board to this pre-set forward rake (and no more)?

3) There will be such large bending and athwartship loading on this 'cantilevered board' and its side support 'plates' as you have drawn them, that is why I would not eliminate the the side stays.
And therein arises another obstacle with this single board idea,...where can I attach those side stays without pulling the side plates apart?

 

Ventilation of the Board(s)

Here is an interesting short study that seems to support the notion that the asymmetrical shaped board tends to NOT ventilate as much as the symmetrical one.

 

#1 agreed - but give a bit more rake -- who knows what uses will be discovered?
#2 agreed
#3 actually its due to you and Doug. You are perfectly correct that now we can foil large cats on quite long and slender CRP structures. So I feel stays are needed only if the board is wood based.
add the side supports