Rick,

1. The way it is slopped, the total height is reduced by 800 mm when folded. So height on the trailer for the lw hull goes from 3.5 m (11' 6") to 2.7 m (8'10") considering 0.5 m of ground clearance on the trailer. I love that it is the difference between going through instead of hitting an underpass. I am now even considering folding the 2 hulls to the total height of the bridgedeck (1.95 m) for trailering and find a way to fold to 10' wide for motoring and berthing in a narrow space. If reduced to 1.95 m folded, total height would be reduced by 1.1 m for a 1 m high lw hull and 0.9 m bridgedeck clearance.

 

I cannot see how canting the beam to bring the lw hull up when folded would add extra weight. It should not be more complex then folding non canted beams, same rotation points and pins. It is the best way I could think of ... maybe someone could find a better alternative ?

The only added weight is to make a canted layer around the mast … hopefully marine ply form around the mast covered with carbon would do it. 

Remaining but not the least is to make a rotating brace for the canted beam...

 

Will do the beam fairing :-) but as the last step when very close to finishing since I am now changing the drawing so much that I would loose too much time doing it now, much simpler to change the square box.

 

2. Found that A Look at Wave-piercing Bows on Multihulls - Sail Magazine

			A Look at Wave-piercing Bows on Multihulls - Sail Magazi...   A Look at Wave-piercing Bows on Multihulls
			View on www.sailmagazine.com	Preview by Yahoo

 

3. I was thinking of putting fresh and grey/waste water tank down in the ww hull and using the connections for piping, I guessed it is the best place in the whole boat to have all big weight ? 

Very interesting idea to be boarding on ww side (having a door on both side of the bridgedeck). Will see how much weight it add. I am adding 1-2 ft of length in the middle of the bridgedeck anyway.

 

I was planing to have enough low density foam filled sealed volume to float even if all the remaining volumes would be filled with water (up to the door sill of the bridgedeck obviously :-) ... maybe I am being paranoid but it would make for a super comfy floating bouey if all hell brake loose ? Still will have to calculate added weight of foam !!!

 

4. Would very much like to see a sketch or picture of this rudder connection ! Any idea how much weight an hydraulic rudder add ? 

Or even a cable loops hidden in the beams, like aircraft controls ... the huge advantage I see is that as with hydraulic, cable could be made to work in all degree of folding.

 

Or kevlar rope “www.dupont.com/products-and-services/fabrics-fibers-nonwovens/fibers/uses-and-applications/ropes-cables.html”

 

5. So if the mast has to take full moment irrespective, it is already super strong and the strongest is right at the intersection with the top of the lw hull. So I would guess it the an already made super strong “pin” to rotate around (so zero weight added by an additional pin is located elsewhere) and add no strain to the mast, just a different way of resisting the torque between the mast and the beam.

Using mast as pin would also reduce the stress in the hull between the mast and the pin, if the pin was located somewhere else. Wouldn’t the hull be lighter then ?

I fully agree that a brace would reduce substantially the stress (and the weight) of the beams at it’s highest point (near the mast), so will try to make it fit in the design.

 

LucJ, very good idea to brace upward … foiling moth are like this to “hold” the wing “beams” (google images of foiling moth give tons of examples).

 

Look like an added benefits is that it would reduce the stress not only in the beams but also at the base of the mast since the highest stress point moves up (shorter arm between aero forces and support point).  Rick, is that what you and Rob are saying when suggesting to increase “bury” ?

It would then be tension in the brace and compression in the beams, which is much better if the braces are smaller and thinner than the beams. But it would add compression in the mast between the beam and the brace … is that a problem ? I would need to calculate this but my feeling is that I better have compression then no brace and a much bigger moment at the base ?

 

And as LucJ said, braces are out of the water.

 

Thanks for the aero and weight comments, your bringing my hopes up !!!

 

Rick and LucJ, you guys are awesome, I must say I am loving this conversation ! Design is just a hobby (for now at least :-) but it really gets me !

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Posted by: lucsimard@ymail.com

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