Double luff mainsail for cruisers

[Dave_S]

Interesting,

https://www.sail-world.com/news/2183...Ja3Z5BvcaD8sZI

[Dave_S]

Its a double skinned sail coming off both sides of the mast instead of off the centreline, both skins are joined at the leech to give a true wing shape but is made of soft material so it can be reefed and dropped and stored on the boom. You adjust the wing shape by rotating the mast which shortens one side of the wing and increases the other. This should allow you to create more lift, less drag, be able to increase the angle of attack without loosing the air flow.

More power, more speed, and higher pointing. They are designing for the Americas cup but are producing cruiser versions for cats.

Advanced Wing Systems

[44'cruisingcat]

Be interesting to see how they work, and what they cost.

[Jim Cate]

Originally Posted by 44'cruisingcat

Be interesting to see how they work, and what they cost.

Ya know, if ya gotta ask, ya cain't afford it...

It seems that first you need a rotating mast...

Jim

[Redreuben]

Are you sure they are joined at leech ? If mast rotation changes shape then they are going to be different lengths at leech ?

[44'cruisingcat]

Originally Posted by Jim Cate

Ya know, if ya gotta ask, ya cain't afford it...


Jim

Like those parasailors!

[Dave_S]

Originally Posted by 44'cruisingcat

Be interesting to see how they work, and what they cost.

They are a bit cagey about price but claim to be 15 - 20% dearer than normal replacement costs. Which could mean anything replacement costs of what, the sail or the whole mast and rigging, I'm guessing the latter.

I have asked for a quote and I have some info to provide them, some of which needs to come from Schionning. Just waiting for this from them.

[Dave_S]

Originally Posted by Jim Cate

Ya know, if ya gotta ask, ya cain't afford it...

It seems that first you need a rotating mast...

Jim

Yes you need their dedicated mast, carbon or aluminium, two line controls to rotate.

I think the cost will be pretty high, I am due for rigging and sails sometime not to far away, if it's not toooooo much I think I'll be tempted.

[Tillsbury]

And you need to saw the spreaders off too. It doesn’t sound very likely that that is going to make it to the average cruising boat any time soon.

[Dave_S]

Originally Posted by Redreuben

Are you sure they are joined at leech ? If mast rotation changes shape then they are going to be different lengths at leech ?

The idea is to have a different shape on both sides of the sail. This will enable a more efficient shape to the wing. Rather than rotating the mast causing the leech around the leeward side bellies out more and the windward side flattens out more to allow the air to stay attached long after it would detach from a 2D sail.

[Dave_S]

They have a K8 (whatever that is) down at Shionning at the moment that I might go and have a look.

They offer me the statistics on the K8, I've looked them up but I don't understand the capabilities of the boat before. Even if I go out on it I don't think I'll learn much except to see how easy or hard it is to adjust and how well the air stays attached and how it goes up, down, and reefs. Maybe that's enough to know ? They are new which worries and excites me.

[Dave_S]

Originally Posted by Tillsbury

And you need to saw the spreaders off too. It doesn’t sound very likely that that is going to make it to the average cruising boat any time soon.

Average is overrated 😀

[markpierce]

Is one a racer or a cruiser? KISS is for cruisers.

[Pauls]

Wharram designed sails like this for his cats many years ago, with the exception that they were much simplified by not having a rotating mast. Just a double luffed sail, wrapped around a round aluminum tubing mast. They also employed a short gaff at the sail head, not like a typical gaff rigger but instead hoisted with a single halyard, ie they were square tops.

Wharram builders have used them successfully for decades. Wharram said they were a significant improvement going to weather.

The double luff produces a cleaner air flow, without the break in the flow on the low pressure side which is inevitable with the typical Bermudian mast/sail connection.

Used on a cat, the very wide staying base reduces mast compression loads significantly. This enables a decently long mast without spreaders.

[smj]

Originally Posted by markpierce

Is one a racer or a cruiser? KISS is for cruisers.

One can be a performance cruiser, best of both worlds!