[__aeneas]

Saw the video yesterday on YouTube. I wonder what happens if they get into very strong winds or very strong swell - if they tip over, do they get up by themselves? What happens if they submerge?

Apparently they figured out how to do it, but my question is, how exactly are they doing it?

[yardie]

I've actually seen one of these at sea. Not this particular one but a similar autonomous vessel. Large swells aren't a problem. If it floats a swell will pass under it. Breaking swells are a concern and usually occur under gale force winds.

A boat has a displacement that is less than water. Which is how it floats. A small weighted bulb in the keel keeps everything pointing upright. You can mitigate the forces on a sail through 2 ways: heeling is when the entire boat leans to one side, heading up is pointing the wing sail into the wind.

Wingsails are pretty well understood and used extensively in racing. Volvo Ocean Racing (VOR) and America's Cup are 2 examples.

[cromulent]

Back when I was a kid sailing dinghies, we did a competition on the lake of the designer of Miss Nylex. An early and primitive wing sail design, it still kicked ass in high winds and could apparently tow a waterskier.

https://en.wikipedia.org/wiki/Miss_Nylex_catamaran

[__aeneas]

Nice, thank you for taking the time to explain this!

[alexlarsson]

The video said everything on it was 100% submersible and saltwater-proof, and then all you need is an air bubble in the "sail" and it will eventually float up with the right side up, no?

[jasonwatkinspdx]

Well, these have a keel that generally keeps them upright. It's almost certain they've been designed to be self righting if they do get knocked over by a breaking wave. Likewise, they float, so temporary submerging shouldn't be much of a problem provided they're sealed well.

One advantage of this kind of wing sail is it's "self trimming". With the tail/tab in neutral position, it'll always weathervane to follow the wind. With the tail tab deflected somewhat, it'll weathervane with some amount of angle of attack. So even in very heavy winds, all it needs to do is back off on the angle of attack and it should be in a relatively stable state.

[mhb]

Isn't that what a keel does?

[ilikepi]

The keel of a modern sailboat does provide "righting moment" to help keep the boat upright, but it's also used to provide hydrodynamic lift in opposition to the sails so that the boat can sail somewhat upwind. These two goals have to be balanced against each other and against performance in the context of mass and friction.

I suppose though a drone has more flexibility in design parameters by not having people and people-related supplies on board.

[__aeneas]

Yes, but a keel is also limited right? It's still possible to tip over and - if potentially submerged, not come back up?

But to be honest, I have very little knowledge on this topic, so maybe a keel is all it needs!

[kpil]

As long as it not fills with water, I'd say it will right it self.

On a traditional boat the sails can dig down in the water and needs to be released rather quickly, and you don't want the hatch to be open, but neither of this seems to be a problem here.

[usrusr]

Theoretically, a sailing sensor drone could even be constructed as a submarine, sailing on the surface in regular conditions but able to dive into the currents if conditions get too harsh. It would not be able to maneuver or communicate while submerged, but it could resurface on a timer, or use sensor data to identify to make an educated guess. (This could also qualify as a piracy countermeasure, should the drones get targeted for parts)

[arca_vorago]

I would think this would be a perfect application of a deep, full keel (which offers the maximum stability and self-correction, but in a manned sailboat tends to be too deep to bring into certain places which is why so many sailboats don't have full keels.)

That said, I don't know much about sailing other than it being on my bucket list of things to learn so I've been reading up on it, and I've been actively searching for a good simulator that works on gnu/linux... (anyone know of one?)

[abale]

you are correct, the keel will help the sailboat to center itself.

[NicoJuicy]

Have a heavier pole underwater?