Wing Sail Doubles as an Outrigger?

[Philip]

I like trying to think of ways to make multihulls self-righting, and I came up with this one that might actually be a good idea. Thought I'd share:

(A sketch is attached, but I'll give my best description in case it doesn't come through.)

Imagine a monohull with a rigid wing sail, but there is another rigid wing attached to the bottom of the first at a 90 degree angle, such that the second wing sticks off the side of the boat. The two wings attach to the boat via a pivot, such that upon tacking the vertical wing is pushed to leeward and the horizontal wing is pushed up into vertical. The two wings are mirror-image identical, and each with a "leeboard" sticking 90 degrees off the tip of the wing.

The flip-flopping nature of this arrangement means that each wing can have a truly ideal aerodynamic shape for its respective tack, and that the same is true for the leeboard on each wing. If the leeboards have a wedge shape from root to tip, they can give progressively greater buoyant resistance to the wing in the vertical position, as well as effectively dampen the impact of the lee wing on the water when tacking. (a small pontoon may be needed to keep the wing tip out of the water) If done right, the leeboard will be pushed further into the water as it is needed, minimizing wetted surface area.

These wing-outriggers will need to be sufficiently sturdy as well as buoyant, and if they are, they will prevent the boat from becoming stable in an upside-down orientation, all without the need for lead ballast.

Another interesting aspect of this arrangement is that heeling forces will be disconnected from the hull, since the wing and outrigger connect by a pivot. This means the vessel will not heel, will rock less on the waves and be more comfortable. It also means that more wing weight up top will not make the boat unstable. This design could combine the best of mono and multihulls!

Being a rigid wing means there can be no reefing, but there will also be no flogging if the wing is allowed to rotate downwind. I don't know how much of a problem this would be. With the addition of two pivots in the "masts", the wings could be folded back astern for storms and docking.

My drawing includes stays that can both be used to support the wings, or operate wing folding.

What do you all think?

Phil

 

[John Perry]

Interesting concept with or without the proposal for self righting - maybe make a model? You really should join our Amateur Yacht Research Society - ayrs.org - only 10£ UK for on-line membership! You might need the space inside the wing sails to partially fill if you want them to submerge as in your sketch then you would need to empty them to right the boat.

 

[Philip]

Thank you for the reply, John. I see now my side view drawing makes it appear as if the wing in outrigger position is half-submerged in the water. I was trying to be artistic and do some foreshortening, but really I would try to keep that wing out of the water as much as possible. If pushed very hard, a boat designed this way may plunge the wing tip into the water, where the buoyant wing and its foil shape would provide very strong righting force.

I was thinking of making a scale model, but I have no experience with remote control anything, and would want it to be as simple as possible. In building a model, could I use light springs to give the wing a preference toward fore-to-aft orientation? The wing might then be blown to rotate nearly in line with the wind direction but not quite (due to spring tension), giving some lift?

 

[Clarkey]

Sounds like an interesting idea. I was toying with something similar a while ago but in an Atlantic proa format rather than a tacker. A bonus of both configurations is that you don't need to use symmetrical foil sections but can have each wing optimised for the tack it will be driving on.

 

[myszek]

The idea is not quite new, see:
Prao – Page 4 – Foilers ! https://foils.wordpress.com/category/prao/page/4/
I wish someone to make it real anyway

regards

krzys