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Old 25-07-2016, 20:47   #16
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Re: Why? Jibs on America’s Cup Catamarans

Perhaps a soft jib can be made a better airfoil, especially for the weight.

It's not just a wing "sail", but a wing "mast". You have to have a solid spar to hold everything up there, and to keep it from messing up the airfoil--on both tacks, no less-- make the mast all "sail".

The jib doesn't have to be a structure supporting other stuff.

Just a guess....
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Old 25-07-2016, 22:07   #17
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Re: Why? Jibs on America’s Cup Catamarans

I'd have to say it's for balance. At speed, these guys are riding on their foils, and I would guess a balanced helm is mighty important.
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Old 25-07-2016, 22:23   #18
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Re: Why? Jibs on America’s Cup Catamarans

So I went and looked and the crew indicated that theboat is actually faster in winds above 12kn without it, but they need it for maneuverability. A point that was driven home when during early boat testing the boat wound up sailing backwards due to catching the bow on a wave during a tack.
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Old 25-07-2016, 22:24   #19
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Re: Why? Jibs on America’s Cup Catamarans

Watching the world match racing tour in M32 cats, backing the jib is an integral part of tacking these boats, especially in heavier air and seas.

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Old 26-07-2016, 08:40   #20
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Re: Why? Jibs on America’s Cup Catamarans

Don,

The M32's don't have a jib, they sail upwind with just the main, the forsail is a spinnaker for down wind only.
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Old 26-07-2016, 09:48   #21
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Re: Why? Jibs on America’s Cup Catamarans

balance and reduces weather helm.
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Old 26-07-2016, 09:53   #22
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Re: Why? Jibs on America’s Cup Catamarans

[QUOTE=Guy;2174747]
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Originally Posted by a64pilot View Post
Wonder how long it will take until these wings sprout slats, maybe slots and vortex generators?
Would the rules allow such?



Then I suppose a winglet would be next?
Maybe, except for weight and complexity why not?

Maybe an end plate?
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Old 26-07-2016, 10:24   #23
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Re: Why? Jibs on America’s Cup Catamarans

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Don,

The M32's don't have a jib, they sail upwind with just the main, the forsail is a spinnaker for down wind only.
What ever you call it, the M32 foresail is not just used going downwind. It is used upwind in light air, for tacking in a seaway, and in the pre-start maneuvers.

This was the first year the world match tour used cats. While the racing is more spectacular from a spectator standpoint, the tactics have COMPLETELY changed from monohull match racing because you lose so much ground on each tack. The America's Cup boats will use similar tactics, which are basically to ignore the other boat after the start and bang the boundaries unless there are huge windshifts.
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Old 26-07-2016, 10:53   #24
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Re: Why? Jibs on America’s Cup Catamarans

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What ever you call it, the M32 foresail is not just used going downwind. It is used upwind in light air, for tacking in a seaway, and in the pre-start maneuvers.

This was the first year the world match tour used cats. While the racing is more spectacular from a spectator standpoint, the tactics have COMPLETELY changed from monohull match racing because you lose so much ground on each tack. The America's Cup boats will use similar tactics, which are basically to ignore the other boat after the start and bang the boundaries unless there are huge windshifts.
They haven't used them upwind so far as I know, but certainly to control the bow while tacking, or to drive it down instead of getting caught head to wind.

At 1:26 is a nice example of this, when the boat in front pulls out about five feet of sail to drive the bow down.

I don't think the tactics have changed all that much, boats are still going hunting after each other (again look at the above start), and there is just as much or more tight manuvering. The major difference is once you get in front it's harder to stay there, because the boats are capable of such high speeds.

The AC is a little different, those boats are racing at almost double the speeds of the M32's and frankly I don't think the crews have gotten them under control yet. But so far all the AC races have been fleet racing, where banging the corners on the short courses is important, when it comes down to match racing I think it will change.
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Old 26-07-2016, 11:43   #25
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Re: Why? Jibs on America’s Cup Catamarans

Tacking/gybing the boat - the headsail, however relatively small, does pull the bow across. As was pointed out - minimize weather helm. Downhill - that extra bit of speed, as well as controlling weather helm.
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Old 26-07-2016, 13:46   #26
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Re: Why? Jibs on America’s Cup Catamarans

https://youtu.be/yoOjcDf_dJA?t=1m6s a few seconds in you can see the jib interact with the mainsail and probably help save the boat.
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Old 26-07-2016, 14:06   #27
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Re: Why? Jibs on America’s Cup Catamarans

When I think back on the first AC in which a wing sail was used (Oracle trimaran v Alinghi catamaran in Valencia) Oracle took their jib down while sailing up-wind and their boat speed increased. So I don't think the jib enhances upwind performance.

Also if the AC rules "require" a jib, does that make it mandatory to hoist it and who decides when? I guess I'm suggesting that such a rule would have little effect on the way the boat is sailed.

But that's just me speculating . . . .
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Old 26-07-2016, 18:06   #28
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Re: Why? Jibs on America’s Cup Catamarans

those two hulled boats with wind down L plates will sail on small jibs alone /there is one over at Hamilton island it goes like a cut snake
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Old 29-07-2016, 11:14   #29
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Re: Why? Jibs on America’s Cup Catamarans

Didn't read through the whole thread, so probably plenty of explanations.

Jib serves two functions on these A cat boats.

1) promotes more flow over the wing sail.

2) gives something for the driver of the boat to go by. I.E. tell tales. Particularly when going up wind.
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Old 29-07-2016, 11:40   #30
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Re: Why? Jibs on America’s Cup Catamarans

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Without the jib, I suspect the AC boats would have more weather helm than desirable.
I had a unirig racing catamaran.

I adjusted the rudders (and mast) for basically zero weather helm because the boat also had a spinnaker and you needed to drop the tiller to raise and lower that sail sometimes in heavy traffic at the downwind mark.

They could make adjustments for the weather helm. In light wind races, I've seen the AC Boats go to quite a large jib.

Also they definitely hep with maneuvering. I certainly missed not having a jib (and a crew) on the starting line
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