Swing Wing Catamaran Design

Someday I hope to build a larger scale version of my solar electric catamaran SolGato. I’m a big fan trailerable boats, and so my ideal design would be something like a pair of Stilleto Cat hulls with a center platform that features a folding swing wing support mechanism for the hulls. The idea is to have a trailerable Cat that is usable when folded to a narrow beam, but then can be swung open to create trampoline space when out on the water. Ideally the boat would be solar electric with a collapsible hard bimini for streamlined trailering.

Here’s a small model I made to demonstrate the articulation of the swing/folding system. The idea is to make the beams of the platform from U channel or square with a side removed which would accept the short tubular Akas of the hulls which pivot outboard of the beam ends allowing the hulls to swing and lock in a tucked closed position swung out into an open position. When open, the round tube Akas run inside the platform beams and are thru bolted in place. When closed, the short fore and aft aka sections swing into alignment and are joined by a sliding outer section of tube to become one long ridged member. The folding and unfolding would be actuated by lines. When unfolded, the Akas would be pressing against the inside forward face of the platforms beams locking them against the channel acting as a stop when underway.

I realize the most vulnerable position structurally is during swinging/folding so some half round guide plates might be needed at the pivot points for the tubular akas to swing around/against.

Thoughts?

 

What's the size of the full scale boat?

If it's large enough to have accommodation in the hulls, I think this looks like a better option.
Kurt Hughes Multihull Design - Catamarans and Trimarans for Cruising and Charter - 36' Cat 2 Fold Catamaran https://www.multihulldesigns.com/designs_other/cat2fold36.htm

 

Nice prototype!

I can only offer a "half idea" for an alternative. Maybe you could use the bimini hard top / solar roof as part of a vertical folding mechanism. Something that has a hinge in the center and folds upwards. Like two parallelograms. You'd have beams on two levels connecting the two hulls, so that could offer some structural stiffness and weight advantage. I can't think of how this would work though while not allowing the amas to roll while folding. My brain fails me when trying to imagine folding mechanisms or kinematic couplings.

 

Smaller scale. Stiletto hulls are around 27’ with only small sleeping bunks for interior.

I followed the design and launching of Cat-a-fold. I had a similar idea to create a scissoring system and came across their project just as they were in the final stretches of the construction. Very clever the way the hard deck is hinged and folds over the hulls when trailering. I think they ended up running dual masts on it.

Anyway, my design would be much smaller and the folding mechanism a bit simpler. The idea being that the deck area is always intact as a solid structural member creating most of the full width of beam when trailering and folded, then the Amas are extended to increase the beam to create trampoline space when on the water. That way the bimini is supported by the deck and the boat could function more like a motorboat when folded. When things get rough or when navigating narrow waters, the boat can be swung closed into a more cigarette catamaran like power boat configuration with the deck at the rear to get through surf or shore break after beaching. The motors would be mounted to the stern of each hull, so when folded the boat would point much better under power to charge through surf conditions and less likely to get broadsided.

@Dejay -I think I understand what you are suggesting. There have been a few small cat designs that have a two piece deck with a piano hinge down the center to allow it to open and close to a narrow beam for trailering. Have also seen some trimarans with wings that pivot up instead of tucking under like a Farrier.

 

Here’s an example of a pair of Stilleto hulls that have been converted for power sailing cat use. I like the hulls because they are very similar to Hobie hulls with an aggressive bow to cut through surf which really helps in our waters if you want to be beachable.

Also reasoning behind using them is because I know there are some project Stilettos out there with solid hulls but dysfunctional hardware and trailers, so there’s a good chance I could get my hands on a pair of hulls for a reasonable price.