sailfly

How large of a role does mainsail control play during maneuvers?

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Watching the start of the Ineos vs ETNZ race today I noticed that the movement of the main on Ineos does not look nearly as smooth as LR or ETNZ, or even AM for the matter. The unfolding of the sail from one side to another is not in line with the rotation of the boat with respect to the wind, its almost as if the boom on Ineos has to overcome a kink or something. This can be seen clearly observed comparing the timing of the flipping of mainsail of the respective boats with the flipping of the headsail. Ineos seems to be half a second behind while all the other boats flip the main in sync with the headsail or before. Tried to use clips with similar amount of rotation.

Look at when Ineos falls off the foils in Race 1 of today. (the timestamp is embedded with the link just press play)

Compare this to ETNZ in the light air conditions in Race 12 against LR yesterday. This was a maneuver with a similar amount of rotation to the Ineos example. Look how much faster the bottom batten unkinks compared to Ineos. (the timestamp is embedded with the link just press play)

And here is LR. (the timestamp is embedded with the link just press play)

Could not find a light air POV of AM but here is a maneuver with a similar amount of rotation. Even though the boom doesn't bend much the skins shift much more quickly than Ineos. (the timestamp is embedded with the link just press play)

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Many thanks for these very interesting pieces. It is not only the communication which I find very interesting and educational.

You are right on the money: It is the importance of the mainsail control (led) by the best possible crewmember for the job. I think this will be their first item to improve on. 

My opinion about the Frackers is that they are not 100% up to speed about real apparent wind sailing. Not enough practice with the AC75 and probably not foiling Moths enough. Also the big surface of the foils might be hindering the speed whilst coming up during the manoeuvres. Could also be a reason that the system gets tired. Imagine some smallest pieces of dirt in the hydraulic oil and there you are. FCS overloaded. But than, what do I know?

 

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Awesome clipping @sailfly and great observation. 

Would also be interesting to have @MaxHugen or @erdb or one of those making models to quantify the difference in lift drag with less optimal trim, to put in perspective the percent differences in speed.

 

 

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8 hours ago, sailfly said:

...

Compare this to ETNZ in the light air conditions in Race 12 against LR yesterday. This was a maneuver with a similar amount of rotation to the Ineos example. Look how much faster the bottom batten unkinks compared to Ineos. (the timestamp is embedded with the link just press play)

The footage from your timestamp and beyond shows an alarming level of shape forming that ETNZ are doing, particularly in their general clew setup. 

The macrame basket is really active, as is the big ram, as are the two push rods, so say nothing of the general leech tensioning. It is certainly way more active that anyone elses (at this stage).

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Also look at jibs.  AM and ETNZ ar least, and I think Prada, have floating up/down jib cars.  Ineos only appears to have in/out and a clew board with multiple holes.  No real way to actively camber/flatten that setup other than maybe via forestay adjustments, which have other side effects.

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This is 

20 hours ago, rh3000 said:

The footage from your timestamp and beyond shows an alarming level of shape forming that ETNZ are doing, particularly in their general clew setup. 

The macrame basket is really active, as is the big ram, as are the two push rods, so say nothing of the general leech tensioning. It is certainly way more active that anyone elses (at this stage).

The change in shape is what prompted my question about how they are changing the camber. It is clear that the Kiwi's are making the bottom of the main deeper as they tack and flattening as they pick up speed but watching these videos has not helped me understand how they do it.

Not by way of explanation but rather observation, I did notice the line running from the bottom of the big ram up to the middle of the jib track which seems to be used through the process. At times the top of the ram is buried between the sails and at time sticks out past the line of the leech. I couldn't identify any part of the macrame (great name BTW) basket as the shape changed but this is probably where it happens. The big ram must change the leech tension to allow the square top to twist off as needed to modify drag and power. 

Thanks for your thoughts, Dan 

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Thank you Gilles.
This is not during Maneuverers but I bet it is a big part of control. 

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Trivial question but it’s bugging me: why do the camber stripes get thicker the higher up the mast they are?  Is it just so they look the same width to a camera mounted at deck level?

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23 minutes ago, sosoomii said:

Trivial question but it’s bugging me: why do the camber stripes get thicker the higher up the mast they are?  Is it just so they look the same width to a camera mounted at deck level?

Optical Delusion?

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7 hours ago, Rasputin22 said:

Optical Delusion?

Parallax ?

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14 hours ago, sosoomii said:

Trivial question but it’s bugging me: why do the camber stripes get thicker the higher up the mast they are?  Is it just so they look the same width to a camera mounted at deck level?

Yes, as seen on a number of Grand Prix boats for a reasonable amount of time now, deck mounted cameras looking up from cockpit floor and middle of the foredeck. In the Med TP fleet, only Provezza differs as she has thicker stripes down low, mast mounted camera looking down.

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17 hours ago, sosoomii said:

Trivial question but it’s bugging me: why do the camber stripes get thicker the higher up the mast they are?  Is it just so they look the same width to a camera mounted at deck level?

Its a function of the sail shape aquisition software - most likely http://www.vspars.com/ - when capturing from deck level, it keeps the projected thickness of the stripe similar from base to head and easier for the camera / software to keep track of.

 

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The boats have very different solutions to the main as noted above.  This is what it looks like to me:

NZ: boomless with extensive controls for inhaul, outhaul, and normal trimming.

LR: boom under the deck.  No traveler cars are seen in the slot at deck level.

IN: tacking boom above deck.

AM: tacking boom above deck with less range.

I keep hoping to see AM improve their setup for shape at the bottom of the main. 

 

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I still don't think LR have any kind of spar below deck.  Why would you?  It's more likely just a track since it only needs to move along the radius of the foot.  To have any meaningful control they'd need to be moving the track/car fore/aft, which doesn't look possible with their slot unless the whole deck skin is moving. 

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6 hours ago, RMac said:

I still don't think LR have any kind of spar below deck.  Why would you?  It's more likely just a track since it only needs to move along the radius of the foot.  To have any meaningful control they'd need to be moving the track/car fore/aft, which doesn't look possible with their slot unless the whole deck skin is moving. 

the lack of a traveler track is an indicator, and this is more definitive: https://www.sail-world.com/news/222806/Americas-Cup--Bertelli-still-critical-of-AC75

"Peculiarities of Luna Rossa?

"We are the only ones with the mainsail boom inside the boat.""

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Might be a case of saying boom and meaning something that acts like a boom but isn't?  Sorry to seem picky here, but there's no reason to have an actual spar under the deck if you've got that slot.  I would bet that they have a track. 

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