How do those new Double Mainsail's on the AC72's work?

rpwillia

rpwillia

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Sep 29, 2008
1,944
Catalina 310 #185 Quantico
I saw a mention and in Youtube videos it looks like there are two sails sewn together with the cuts opposite. Apparently the pro's like them as there is very little flapping when tacking and they get into shape much faster. Always wondering when the trickle down technology reaches us.
 
M

markwbird

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Nov 26, 2012
1,654
C&C 40-2 Berkeley
It's not really a double mainsail so much as a rigid wing with a joint to allow it to fold. It is a rigid structure that has a joint so that the back half of the wing can fold like the flaps on an airplane wing. Folded it is more powerful (generates more lift) but also creates more drag. As such it is like a lower gear. As the boat picks up speed the wing can be straightened out to a "higher gear". This is my understanding anyway. If anyone out there has more to add please do. I do know that the wing can only be removed from the boat with a crane. It cannot be dropped.
 
shemandr

shemandr

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Jan 1, 2006
7,585
Slickcraft 26 Sailfish
So the double luff sail ends up looking like a wing really looks? I'm not clear on whether they devised this sail in order to have a sail that can be raised and lowered and will prevent turtling. Or if they devised it to have a more efficient shape? That rigging diagram doesn't make much sense to me.
 
shemandr

shemandr

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Jan 1, 2006
7,585
Slickcraft 26 Sailfish
It's complicated - I guess. The Cup is coming up quickly. I didn't realize ...
 
DArcy

DArcy

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Feb 11, 2017
1,769
Islander Freeport 36 Ottawa
shemandr said:
So the double luff sail ends up looking like a wing really looks? I'm not clear on whether they devised this sail in order to have a sail that can be raised and lowered and will prevent turtling. Or if they devised it to have a more efficient shape? That rigging diagram doesn't make much sense to me.
Click to expand
It sounds like they were trying to make it easier and cheaper to rig. They are also more robust than the catamarans. The last boat would need a lot of repairs when they capsized. There have been capsizes on the new AC75s where they just right it and keep on sailing.
 
shemandr

shemandr

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Jan 1, 2006
7,585
Slickcraft 26 Sailfish
rpwillia

rpwillia

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Sep 29, 2008
1,944
Catalina 310 #185 Quantico

Interesting. Some have a boom and some do not. I read they can have tapered battens as well as a comment the batten makers should be busy trying things.
Interesting on how they attach with a single line with a Y type connected to both clews.
1607054726313.png
1607054964719.png
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,140
CAL 35 Cruiser #21 moored EVERETT WA
Sailors, alcohol, and brainstorming - which one of these words does not belong.
 
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Hunter216

Hunter216

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Sep 22, 2018
1,869
Hunter 216 Kingston
jssailem said:
Sailors, alcohol, and brainstorming - which one of these words does not belong.
Click to expand
Well based on the number of threads on this “sailor” site “brainstorming” about what their favourite “alcoholic” beverage is I would say they appear to ALL go together :)
 
rbringle

rbringle

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Jan 22, 2008
80
Gulf 29 Little Current, ON
I was associated with Tri-Cat Trimarans, a builder in Kent, CN. They build Patient Lady II or III (not sure), a C-Class catamaran designed by Dave Hubbard that competed successfully in the "Little Americas Cup." I was only on hand when they were building the hulls, not the rig, but I think it was the first competitive sailboat with a fixed wing rig that had adjustable camber. Here is information on Dave Hubbard's legacy to the both the fixed wing sail and the soft sided version: Hubbard, David - National Sailing Hall of Fame
Here's some history of that period: Wing-sails had early development on Long Island Sound
 
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rbringle

rbringle

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Jan 22, 2008
80
Gulf 29 Little Current, ON
rbringle said:
I was associated with Tri-Cat Trimarans, a builder in Kent, CN. They build Patient Lady II or III (not sure), a C-Class catamaran designed by Dave Hubbard that competed successfully in the "Little Americas Cup." I was only on hand when they were building the hulls, not the rig, but I think it was the first competitive sailboat with a fixed wing rig that had adjustable camber. Here is information on Dave Hubbard's legacy to the both the fixed wing sail and the soft sided version: Hubbard, David - National Sailing Hall of Fame
Here's some history of that period: Wing-sails had early development on Long Island Sound
Click to expand
I forgot to mention that that work was in the mid-1970s.
 
Hunter216

Hunter216

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Sep 22, 2018
1,869
Hunter 216 Kingston
1983 Fred Haywood 30 knots on a windsurfer powered by a carbon fibre “wing mast” rig that was so unstable it couldn’t be gybed. The “new” tech perhaps isn’t as new as we think :)

791635B9-6592-41EF-AA33-A46362A3D29D.jpeg
 
joker460

joker460

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Apr 27, 2010
968
Beneteau 352 Hull #276 Ontario
The wing sail was in development back in 2014 by Beneteau for general distribution but it seems it never got any further.

 
DArcy

DArcy

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Feb 11, 2017
1,769
Islander Freeport 36 Ottawa
Several years ago I had an online conversation with Yves-Marie Tanton about wing sails. He had some great thoughts and had looked into them for his designs but we came to the conclusion that, although there was some performance advantage, the challenges associated with reefing and stowing a wing sail were not worth the small gains. A lot of it is also related to the hull design. Putting a wing sail on my portly cruiser would have no performance advantage. A wing sail on a ULDB would have some advantage for some points of sail. Wings on the AC72 did have an advantage because they foil upwind. Downwind, once up to speed, the apparent wind goes forward enough that they are always either close hauled or on a close reach.
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,140
CAL 35 Cruiser #21 moored EVERETT WA
While visiting the Annapolis Boat show there was a booth marketing a parasail shaped spinnaker. It was reported as being a safer alternative to the traditional spinnaker or asymmetrical.
 
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