strider470

Luna Rossa Challenge. AC 36

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5 minutes ago, Ex-yachtie said:

If it was a structural modification, wouldn’t you expect it to change in dimension along its length?  If it’s some sort of stiffener there’s no reason for it to be that deep at the bow.

And perhaps it wouldn't have vertical glue lines along its length if they were looking for a stiffener.

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Just now, mikenz2 said:

Main sail.

Nah, the flat blanket below it - hiding the “boom” surrogate, I suppose

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Just now, Xlot said:

Nah, the flat blanket below it - hiding the “boom” surrogate, I suppose

Ah, it's a padded cover they put down to protect the deck when they're not sailing. It''s feature-less underneath:

image.thumb.png.50b7cdd1d219a476e74fef7f4783d30e.png

 

They have a foredeck cover too:
P1150608.thumb.JPG.34cc7fecf83c675ba54e4cce3864cb8a.JPG

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1 hour ago, mikenz2 said:

It arrived on the ship with Boat 1, it was wrapped and labelled "Rig 2".

Seen 10th November:
P1180291.thumb.JPG.7b48d0851062ffc48889c2d269374ca9.JPG

 

Sorry for being thick, the angle and light on the other pic made it look much shorter and messed with the shape a bit

carry on snooping Sir! 

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Just now, JALhazmat said:

Sorry for being thick, the angle and light on the other pic made it look much shorter and messed with the shape a bit

carry on snooping Sir! 

Don't be sorry - it was messing with my head big time too :-)

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12 minutes ago, enigmatically2 said:

right hand one is 17, not 27 I think

Ooops, you're right !

2-1.png

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2 hours ago, Xlot said:

Nah, the flat blanket below it - hiding the “boom” surrogate, I suppose

Looks like a big sling they use to crane the mainsail on/off the boat - kinda like a stack-pack/lazybag except removable. They use similar things a lot for superyacht sail installs/removals...

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Three new videos by Justin Mitchell. Close racing with AM. At the end of video 84 there is a sort of  "speed test". My opinion is that LR is faster in a straight line, but AM tacks and gybes more dry. LR sometime touch the water in the last part of the tack / gybe, after going on the two foils, when is back on one foil only. AM had more time on the water, so maybe it's just practice. Or maybe is a trade-off of the new LR B2, that seems also to fly even, not too much bow down, and not overheeled compared to B1. Strange, because what Max and Bertelli always said is that all the boats will have pretty much the same top speed, and the key element to win will be stability and maneuvers. Maybe they need just more time on the water. 

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8 minutes ago, Zaal said:

 

Three new videos by Justin Mitchell. Close racing with AM. At the end of video 84 there is a sort of  "speed test". My opinion is that LR is faster in a straight line, but AM tacks and gybes more dry. LR sometime touch the water in the last part of the tack / gybe, after going on the two foils, when is back on one foil only. AM had more time on the water, so maybe it's just practice. Or maybe is a trade-off of the new LR B2, that seems also to fly even, not too much bow down, and not overheeled compared to B1. Strange, because what Max and Bertelli always said is that all the boats will have pretty much the same top speed, and the key element to win will be stability and maneuvers. Maybe they need just more time on the water. 

I'm not convinced. Initially after AM tacks, LR is faster yes. Then AM gets up to speed and they seem more equal, then the angles change, AM is pointing higher than LR so you can't judge. Then after they tack again, they both bear away for downwind bit and AM seems to be pointing more downwind.

So although LR may appear at first sight faster, she may not be, and her VMG may certainly be worse

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7 hours ago, weta27 said:

 

DSC_1315.jpg

 

 

 

Interesting detail with the deck hollows where the rudder assembly diagonal struts come down - similar issues of superposition for foil to arm juncture?

4 hours ago, mikenz2 said:

Ah, it's a padded cover they put down to protect the deck when they're not sailing. It''s feature-less underneath:

image.thumb.png.50b7cdd1d219a476e74fef7f4783d30e.png

 

They have a foredeck cover too:
 

Have we seen such nice foot camber on the boomed setups? 

3 hours ago, enigmatically2 said:

right hand one is 17, not 27 I think

Larry..

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From one of Weta27 pics, you can see that they didn't extend the keel modification (blade) all the way back. 

977916114_LR2keelmod2.thumb.jpg.19ecce0fc1ba57f349e0f32476bf42b7.jpg

 

Can you imagine the discussions that took place before they did this?

How is the performance of the new hull?  Great, but we need to cut it in half and add a few millimeter blade down the center...

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1 hour ago, buckdouger said:

Interesting detail with the deck hollows where the rudder assembly diagonal struts come down - similar issues of superposition for foil to arm juncture?

Have we seen such nice foot camber on the boomed setups? 

Larry..

There was on ineos b1 

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48 minutes ago, Zaal said:

holes.png.38f0e6cbdd3574200b7ae19b98d43397.png

 

What about this.... "holes" ? 

 

 

 

Turbulators, they copied INEOS again. Either that, or there’s an infestation of the dreaded Kiwi carbon-eating mole

 

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14 minutes ago, Xlot said:

 

Turbulators, they copied INEOS again. Either that, or there’s an infestation of the dreaded Kiwi carbon-eating mole

 

Yes, could be. Just 2 ? Ineos has 4 each side. Maybe is the caterpillar, magneto hydro-dynamic propulsion, like in "The hunt for Red October" ;) 

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Stick on keel, turbulator/ion drive vortex technology... wonder if they are going to ask Ferrari to build some foils next 

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1 hour ago, The_Alchemist said:

From one of Weta27 pics, you can see that they didn't extend the keel modification (blade) all the way back. 

977916114_LR2keelmod2.thumb.jpg.19ecce0fc1ba57f349e0f32476bf42b7.jpg

 

Can you imagine the discussions that took place before they did this?

How is the performance of the new hull?  Great, but we need to cut it in half and add a few millimeter blade down the center...

Doesnt the rotation point of the arms have to sit a fixed point above the bottom of the boat?  


“quick stick a bit on the bottom before the come back and measure it again... “

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13 minutes ago, JALhazmat said:

Stick on keel, turbulator/ion drive vortex technology... wonder if they are going to ask Ferrari to build some foils next 

Well if NYYC go down the same route their motorsport experts will be asking when the Kiwis are going to put the banking in on the corners so that the yachts can turn

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53 minutes ago, Xlot said:

Either that, or there’s an infestation of the dreaded Kiwi carbon-eating mole

The kiwi carbon-eating mole can only be kept at bay by fencing around your compound with no 8 wire.

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6 hours ago, JALhazmat said:

Doesnt the rotation point of the arms have to sit a fixed point above the bottom of the boat?  

 

Figure 13.1 : Foil geometry ~

Foil cant axis 520 mm (+/- 3 mm) above measurement water plane (MWP).

Cant cylinder mount 90 mm (+/- 3 mm) below MWP.

~ bottom (fairbody at centreline) of boat is is not measurement constrained.

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LRB2a.thumb.jpg.04f948bbbc3af7e93a13906baa5cbe1b.jpg

At least a dozen "No step" signs on LR. Bit of a minefield.......Structurally it looks to be all or nothing........Curious as to what the vertical ribbing in the forward cockpits are? They're symmetrical - on both sides. Does it imply there's heat coming from something?.......... Note the two temporary winches straddling the mast. Not there when sailing. 

So instead of a boom, do they have some sort of electromagnet system under the ramp to shape the main?

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JALhazmat is right, it looks like ribbing or a grill but it's just the carbon weave, vertical zig-zag pattern, all around the cockpit walls.

weave.jpg

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6 hours ago, Horn Rock said:

At least a dozen "No step" signs on LR. Bit of a minefield..

The area just forward of the mast and jib track (above the FCS) is open during setup, and they place two or three flimsy-looking covers over it when done.

access.jpg

access2.jpg

access3.jpg

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1 hour ago, weta27 said:

The area just forward of the mast and jib track (above the FCS) is open during setup, and they place two or three flimsy-looking covers over it when done.

 

access2.jpg

access3.jpg

Great, sneaky photos!

I wish we could have a more top-down view and see all the secret goodies down in there!

Maybe @weta27 would be interested in deploying a mini-drone? :D 

 

With so many no-steps looks as if the hull & deck have plenty of non-structural fairings and covers and the inside is quite hollow. Must be difficult to achieve a good stiffness without any continuous and deep bulkheads aft of the mast. Surely that box-ramp below the main is structural and contributes quite a bit to the the overall torsional stiffness.

 

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9 hours ago, Horn Rock said:

So instead of a boom, do they have some sort of electromagnet system under the ramp to shape the main?

Again with the magnets :blink:.

Would strangle the boys with the gold chains.

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very small hamsters sandwiched between to carbon skins that chase small bags of sunflower seeds that are moved by hydraulics to get rodentto move to teh correct location dragging the sail into position. 

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17 minutes ago, JALhazmat said:

very small hamsters sandwiched between to carbon skins that chase small bags of sunflower seeds that are moved by hydraulics to get rodentto move to teh correct location dragging the sail into position. 

Fake news.

Its guinea pigs

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4 hours ago, barfy said:

Again with the magnets :blink:.

Would strangle the boys with the gold chains.

I'm gonna agree on the basis that the required forces would be very hard to come by with any air gap. Gold isn't an issue but it certainly would make things harder if anything ferrous was around. 

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If you wanted to do a true boomless setup that would tension both leech and foot, there's a way to do it with 2 tracks and 4 cylinders.

Mainsheet track would be located just below std leech location and have the same radius as foot length. Have a pair of rams facing upwards controlling leech tension. Rams are attached to toggles on the traveler cars to be able to tilt fore and aft. This is your mainsheet/leech tension.

Have a smaller radius track located ~.5m ahead of that track. 2 cars and 2 rams again, but these rams extend aft and up, and attach to the mainsheet rams with a sliding collar. These rams affect the fore/aft location of the top of the mainsheet rams, so essentially move the clew mostly fore/aft with a little up/down as well. 

You'd need some serious metal in the mainsheet ram pistons, but this would give you 3d control of both clews on the main.  

Just a thought. 

 

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9 hours ago, MastaVonBlasta said:

I wish we could have a more top-down view and see all the secret goodies down in there!

It's been tricky to get good shots of the secret goodies in there.
 

P1150831 (2).JPG

P1150793.JPG

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18 hours ago, Horn Rock said:

So instead of a boom, do they have some sort of electromagnet system under the ramp to shape the main?

Just loose footed.

 

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4 hours ago, RMac said:

If you wanted to do a true boomless setup that would tension both leech and foot, there's a way to do it with 2 tracks and 4 cylinders.

Mainsheet track would be located just below std leech location and have the same radius as foot length. Have a pair of rams facing upwards controlling leech tension. Rams are attached to toggles on the traveler cars to be able to tilt fore and aft. This is your mainsheet/leech tension.

Have a smaller radius track located ~.5m ahead of that track. 2 cars and 2 rams again, but these rams extend aft and up, and attach to the mainsheet rams with a sliding collar. These rams affect the fore/aft location of the top of the mainsheet rams, so essentially move the clew mostly fore/aft with a little up/down as well. 

You'd need some serious metal in the mainsheet ram pistons, but this would give you 3d control of both clews on the main.  

Just a thought. 

 

How would you control twist with that arrangement?

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5 hours ago, Horn Rock said:

So how are they controlling the main Barfy?

Loose footed from the pictures we've seen. Some special sauce of rams to provide at least 2d control of the track point, plus sheeting. There is no evidence of any other sheeting up the foot. Magnets are heavy, and would require electro magnets to have control, electricity is not available.

If after a run many small items are stuck to the sail foot, then it's magnets.

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10 minutes ago, Kate short for Bob said:

How would you control twist with that arrangement?

Top control zone twist plus sheeting? How do any of the teams control twist?

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2 hours ago, barfy said:

Some special sauce of rams to provide at least 2d control of the track point,

So rams to induce that curve in the foot batten?

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42 minutes ago, Horn Rock said:

So rams to induce that curve in the foot batten?

Foot tension and some voodoo flex material in the batten?

Seems easier than big fo permanent magnets..they would have to be cripplingly strong. And how would they release? Drop down into the bilge on little carriages? Seems too hard.

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3 minutes ago, Stingray~ said:

Magnets is a ridiculous idea! 

So are almost all of your thoughts spewbot.

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12 minutes ago, Stingray~ said:

Magnets is a ridiculous idea! 

Tell us more about the app for this cycle please.

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47 minutes ago, barfy said:

So are almost all of your thoughts spewbot.

A bit rich coming from you of all people.

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On 10/23/2020 at 12:29 PM, Zaal said:

 

Just found this interesting interview by sailor / journalist Bacci del Buono with Pietro Sibello, mainsail trimmer of Luna Rossa. 

 

- The softwing / double mainsail is an hybrid of the wingsail and a traditional mainsail. It takes the best of both. The mast (26 mt tall) has a D section. The two mainsail are hoisted on it, continuing the two profiles of the D. The sofwing is more performing than a traditional mainsail and it's a lot easier to manage than the wingsail. If you have any issue during the training you can always lower the mainsail and go back home, without having to take off the entire mast. 

-  Asked by Bacci on what's inside the two sails, Sibello answer that the Rule is open about this, every team is free to design their own system to control the shape of the sails. The softwing can be controlled in two parts of the mast. In the 4 mt at the top of the mast and in the 1.5 mt at the base. Between this two sections you can only choose where to put the battens, and how many of them (although there is a maximum limit on how many battens you can use). You can choose also how to connect the battens to the mast. You can connect them directly to the mast, so they rotate with it, or you can put something between the mast and the batten in order to make it move less when the mast rotate. 

- The mast rotates, and the spreaders are connected to it with a ball, a little sphere that allow the spreaders to keep their position while the mast is rotated.

- They sail at more than  30 knots upwind, with 15 knots of wind. The apparent wind is more than 50 knots, so the aerodynamics is a key element of this boats, and that's why you have to seal the lower part of the mainsail (or the boom) to the deck. You have to be very "clean" very essential, in that part of the boat, and having a boom makes it difficult. He confirms that the current boomless setup is achieved with two semi rigid battens. He adds that of course removing the boom it's not easy, but he's happy about their solution. 

- American magic has a traditional boom, while ETNZ has a boom that is not 100% structural, they use ut to control the camber of the mainsail. 

- The main purpose of closing the gap between the lower part of the sail / the boom and the deck is to avoid the passing of air between the deck and the boom. This could disturb the main air flow creating turbolence. Every team do this, with different solutions. Teams that have the boom put a sort of apron under it and close the gap. He adds that it's difficout to cover the boom without having defects in the shape of the mainsail and in the air flow. If the sail is sealed with the deck it's more clean and more performing. 

- He would choose the wingsail over the soft wing for performances, but the sofwing is a lot more manageable. 

- Asked about the possible future use of the double mainsail in other boat classes, he answer that it's possible it will be used in top races circuits, but not in less competitive environment. Bacci jokes that it will be used in the Sidney - Hobart but not in the  Alassio (a small italian city) Winter Regatta. 

In this interview with Pietro Sibello (mainsail trimmer) he confirmed there are semi-rigid battens at the foot of the mainsail. He can't say more about the control the camber of course, they must "push" or "flex" the battens somehow.  

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16 minutes ago, Zaal said:

In this interview with Pietro Sibello (mainsail trimmer) he confirmed there are semi-rigid battens at the foot of the mainsail. He can't say more about the control the camber of course, they must "push" or "flex" the battens somehow.  

Why "must"?

Battens can bend with the sail pressure, just like on traditional sails. They are just made to be flexible enough. Without a boom it is of course harder to control that bend, but perhaps they think they have enough control from the mainsheet. Given that the AWA is always much the same it is possible. Yes they lose the fine control for wind conditions that a boom gives with the outhaul, but maybe they think that the gains from a smoother end-plating are worth it

:shrug:

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20 hours ago, Kate short for Bob said:

How would you control twist with that arrangement?

Twist of the mainsail leeches would be done with the vertical mainsheet ram, very much the same as with a "standard" ac75 mainsheet ram(s).  Kind of picture the mainsheet and "outhaul" rams coming together to make an inverted y, with the vertical ram sliding on the end of the more horizontal ram.  You get essentially infinite clew positions inside a box, and you can define the box with piston and cylinder body lengths. 

The only hassles here are the lateral forces on the mainseet ram piston, and the weight of essnetially doubling the tracks, cars and rams. 

 

Way back when there was an argument about whether the below deck mainsheet could also be acting as an outhaul (hint: no) or whether the foot tension was being done with battens (hint: yes) but if you wanted to make a totally belowdeck system to do both, this is how you could do it. You would just likely bend a bunch of pistons before getting the spec right!

Again, I don't think LR has this, but it's an idea that could accomplish what some people thought LR was up to. 

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Twist and trimming of the mainsheet/leech would be pretty much the same. The only difference would be that you could also push that ram with the double acting "outhaul" cylinder to angle the mainsheet ram aft, tensioning the foot. The controls would be more like a 3d lead, unless you wanted to change the actuators move both cylinders at once to fake having only outhaul or mainsheet acting at once. The "outhaul" track and car would need a race of bearings above and below the track flange to handle the loads in both directions, but that's been done. 

3d mainsheet.png

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Just picture most of that below deck, with the mainsheet piston sticking up through a wide slot. How wide depends on how much travel the outhaul cylinder needs

 

Also, I know most boats have one single cylinder for the mainsheet, this system needs two since you're positioning both clews seperately via the outhaul rams.  Bet the total system weight is still less than a boom though. 

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5 hours ago, RMac said:

Twist and trimming of the mainsheet/leech would be pretty much the same. The only difference would be that you could also push that ram with the double acting "outhaul" cylinder to angle the mainsheet ram aft, tensioning the foot. The controls would be more like a 3d lead, unless you wanted to change the actuators move both cylinders at once to fake having only outhaul or mainsheet acting at once. The "outhaul" track and car would need a race of bearings above and below the track flange to handle the loads in both directions, but that's been done. 

3d mainsheet.png

Or if you put both the rams below deck, and operate it as a floating jib lead, you'd probably have the solution. Conceptually, you need to control in 2 dimensions, and that's what you've diagrammed out. I just don't think this is how they have implemented it. 

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On 11/17/2020 at 8:39 PM, weta27 said:

JALhazmat is right, it looks like ribbing or a grill but it's just the carbon weave, vertical zig-zag pattern, all around the cockpit walls.

weave.jpg

Side mount intercoolers for the hydraulic fluids, obviously. ;-)

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On 11/17/2020 at 9:45 AM, Horn Rock said:

So how are they controlling the main Barfy?

For magnets to handle those loads they’d need to be electromagnets and that couldn’t be powered given the restrictions. Also unnecessary weight. Absolutely no way they are controlled by magnets. Probably, controlled with simple lines, blocks, and winches that adjust the tension on the battens. Much like a leach line would do.

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Magnetic monopoles might require less power...  8-)

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1 hour ago, I14RACER said:

For magnets to handle those loads they’d need to be electromagnets and that couldn’t be powered given the restrictions. Also unnecessary weight. Absolutely no way they are controlled by magnets. Probably, controlled with simple lines, blocks, and winches that adjust the tension on the battens. Much like a leach line would do.

And the top control zone is playing a huge part in the shapes we see. Problem is it's all hidden from sight.

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Jesus, controlling camber in a sail without a boom is not a new thing. 

Everyone has seen a jib. If it's on a track across the boat (mainsheet traveller), then most systems adjust the twist and foot depth by altering the clew board position (or sometimes tack height). 

It would be easy to have an adjustable clew board between the twin skins. So it's most likely that. If you want to adjust the sheeting angle at deck level, then you need cars that move forward and aft (see RMac post). But that soon takes up lots of deck space and I don't think the deck opening at the traveler is large enough for this. 

The downside to this is the mainsheet carries enormous load as it's doing the job of both mainsheet and outhaul. This is why boomless cat's end up with massive purchase systems. 

The other disadvantage is the sheeting angle changes as you ease the sail, so to replicate the easing characteristics of a boom set up you would have to be co-oridnate traveller, mainsheet and clew position (similar to moving jib cars forward as you ease the sheeting angle to retain leech tension). This is quite dramatic and it it logistically difficult to get enough range of movement at the clew to ever compensate for this. The feedback from INEOS was that they couldn't get the sail flat enough with the boomless set up. 

Then you also have mast rotation. I think the boats with booms are pushing off them to rotate the mast, like the tasar spanner. With luna rosa this has to be done below deck. And again, it won't automatically change as it's not physically linked to boom movement, so it's another system you have to co-ordinate.  

But, the benefit is you can have a nice camber in the bottom of the sail. But with the other taking the booms so low, you have to wonder if it's worth it. 

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14 hours ago, atwinda said:

Or if you put both the rams below deck, and operate it as a floating jib lead, you'd probably have the solution. Conceptually, you need to control in 2 dimensions, and that's what you've diagrammed out. I just don't think this is how they have implemented it. 

I don't think so either, seems like they just use a batten with some kind of variable tension.  That I think would be cool to see.  Could be tubular telescoping battens with a ram. 

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Nice videos by Roger Mills and NZSP.

In the first video seems that LR is trying to not go down with the hull after completing the tack, when is again on one foil. At 2:52 there's maybe a hint on what they're doing. Seems they change the angle of attack of the foil to prevent the hull going down, "pulling up" the boat. Then they have to change again the angle of attack, and sometimes they change it too fast it seems, so they go down. Any thoughts ? 

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I think all are realising its better to kiss with their skegs after slowing in turns than wheelie to stay dry, and crash stop. Weird bottom designs now seem more obvious? It's like running a drunken three legged slalom race with dwarfs in high heels. 

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1 hour ago, Priscilla said:

Just came by the Handbags compound plenty of noisy grinding going on.

I wonder which boat they're chopping up to look like Te Rehutai - B1 or B2?

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24 minutes ago, Zaal said:

No sailing today for LR ?

They're practicing racing required for their participation in the AC36 match.

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9 minutes ago, Zaal said:

No sailing today for LR ?

Doing what they did the last time they competed in the AC in Auckland, chopping the bow off and making a new one lol

 

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1 hour ago, Forourselves said:

Doing what they did the last time they competed in the AC in Auckland, chopping the bow off and making a new one lol

 

I guess that is slightly better than waiting for it to fall off again :mellow:

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Just watched an interesting Instagram Live with Max Sirena for GQ Magazine. He talked about the Cup in general and he added something cool:

- Every boat creates a "vortex" of air under the bow, an air cushion visible in some pictures / video ( @weta27 @mikenz2 did you ever noticed this ?)

- Sailing in the Ocean is more difficult than in the Italian sea, where they could see the foils underwater and control them accordingly

- B and C race courses are the most shifty. Some days ago during a session wing angle changed by 34º in four seconds

- Crew ability can improve boat performances up to 30%

- They'll prefer average speed vs top speed

- They have some ideas about where they stand against the other challengers, but you don't know for real until you line up in a real race

 

 

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11 minutes ago, Zaal said:

Just watched an interesting Instagram Live with Max Sirena for GQ Magazine. He talked about the Cup in general and he added something cool:

- Every boat creates a "vortex" of air under the bow, an air cushion visible in some pictures / video ( @weta27 @mikenz2 did you ever noticed this ?)

- Sailing in the Ocean is more difficult than in the Italian sea, where they could see the foils underwater and control them accordingly

- B and C race courses are the most shifty. Some days ago during a session wing angle changed by 34º in four seconds

- Crew ability can improve boat performances up to 30%

- They'll prefer average speed vs top speed

- They have some ideas about where they stand against the other challengers, but you don't know for real until you line up in a real race

 

 

Thanks for providing these summaries Zaal, much appreciated.

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14 minutes ago, Zaal said:

- Crew ability can improve boat performances up to 30%

I reckon, given the chance, I could reduce it by way more than that. 

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32 minutes ago, Zaal said:

Just watched an interesting Instagram Live with Max Sirena for GQ Magazine. He talked about the Cup in general and he added something cool:

- Every boat creates a "vortex" of air under the bow, an air cushion visible in some pictures / video 

 

Yer well a Vortex is a low pressure area, not an air cushion. Max Sirena is not any expert in this area. And yer there are plenty of vids and pics showing spray being lifted by the low pressure areas. It's called the Venturi effect, named after the man that discovered it Giovanni Battista Venturi was also Italian https://en.wikipedia.org/wiki/Giovanni_Battista_Venturi. Like most managers Max Sirena knows Sweet FA about physics.

 

 

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This time it wasn’t a recorded interview but an Instagram Live. I try to be as accurate as I can in my translations but it’s a lot easier when I can listen again what people say. I used the wrong word, sorry. My mistake, not Max’s. Anyway, thank you Laser ! Really interesting, I watched again videos and pictures and I saw it. 

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42 minutes ago, Zaal said:

This time it wasn’t a recorded interview but an Instagram Live. I try to be as accurate as I can in my translations but it’s a lot easier when I can listen again what people say. I used the wrong word, sorry. My mistake, not Max’s. Anyway, thank you Laser ! Really interesting, I watched again videos and pictures and I saw it. 

Sorry to quote myself, I’m sure Max talked about ground effect talking about the boat flying so near to the surface, and than he talked about the air cushion created by the bow of all boats

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No worries, and no dig intended. Lost in translation, the bane of science, but possibly the making of humanity?

 

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1 hour ago, laser 173312 said:

Yer well a Vortex is a low pressure area, not an air cushion. Max Sirena is not any expert in this area. And yer there are plenty of vids and pics showing spray being lifted by the low pressure areas. It's called the Venturi effect, named after the man that discovered it Giovanni Battista Venturi was also Italian https://en.wikipedia.org/wiki/Giovanni_Battista_Venturi. Like most managers Max Sirena knows Sweet FA about physics.

 

 

And you know sweet FA about wining the cup so I recon he will sleep easy after your stinging criticism. 
 

and actually vortex is correct as it describes the rotation of air following interaction with a surface (the bow) 

the air if of sufficient velocity will tumble and rotate into a spinning vortex, it’s that that is seen lifting water from the surface.

go read up on F1 aero and the use of vortices to aid aero performance 

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8 hours ago, JALhazmat said:

And you know sweet FA about wining the cup so I recon he will sleep easy after your stinging criticism. 
 

and actually vortex is correct as it describes the rotation of air following interaction with a surface (the bow) 

the air if of sufficient velocity will tumble and rotate into a spinning vortex, it’s that that is seen lifting water from the surface.

go read up on F1 aero and the use of vortices to aid aero performance 

Yer I started reading about it in 1978 I can recommend 

https://r.search.yahoo.com/_ylt=AwrJQ6CLrbxfQ30A5h5LBQx.;_ylu=Y29sbwNpcjIEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1606229516/RO=10/RU=https%3a%2f%2fwww.amazon.co.uk%2fLotus-78-79-Ground-Effect%2fdp%2f1847971431/RK=2/RS=XTC9s2qwNYbaOJQSEq_dt2quJNc- 

which explains all about the low pressure systems. "air cushion" my ass.

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Great, then you can see the lack of Side skirts that would affectively Seal the sides creating the pressure differential Between the air flowing under the boat and the surrounding it to make that work on a boat. 
 

The Vortex of spinning air is it trips off the hard edge of the keel around the nose area on the boat Is what’s being seen and is 100% not what is being described in the 1978 lotus  ground affect link you put up

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14 hours ago, Zaal said:

- B and C race courses are the most shifty. Some days ago during a session wing angle changed by 34º in four seconds

Brad, do you see any angle where we can drop these tracks off the menu? They give us the shits and Barker will hammer us.

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7 hours ago, JALhazmat said:

Great, then you can see the lack of Side skirts that would affectively Seal the sides creating the pressure differential Between the air flowing under the boat and the surrounding it to make that work on a boat. 
 

The Vortex of spinning air is it trips off the hard edge of the keel around the nose area on the boat Is what’s being seen and is 100% not what is being described in the 1978 lotus  ground affect link you put up

It was the phrase "air cushion" that I thought was stupid, Stupid.

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32 minutes ago, laser 173312 said:

It was the phrase "air cushion" that I thought was stupid, Stupid.

Na. you recon max knows fuck all and described the wrong phenomena

stupid.  
 

you ever try describing stuff in a second language? 

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Just watched again the Max Sirena interview in the GQ IGtv channel. Here what Max says: 

 

- Wind shift was 28° in four seconds on B/C course

- They have three PLC on-board, and one thousend sensors

- They started with 20 knots take off speed, now they are at 16.5 knot

- Pitch angle of the boat is balanced with the angle of attack of the foils and "elevator" (the rudder foil)

- Sailing windward you want the hull to be as close to the surface as possible (he call this "kissing") creating a ground effect and closing the gap between the hull and the surface, because you need power and righting moment. Sailing downwind instead you have to be a little more high, you want the boat to be as light as you can, and with less wet surface, so arms and rudder stay more out of the water. The boat's trim also change, you are more flat and less pitched down. (edit: here he talks about the vortex you can see in some pictures/videos. "Air cushion" was a phrase of mine)

- They have different configuration for every wind condition

- Crew can improve the boat performances up to 20/30 % in a single week. Every team will improve a lot during the Prada Cup.

- There's an issue with the Defender. ATNZ wants to increase the number of practice day (edit: with the other Challengers? Or alone? Is Max talking about the ACWS or about something new?). Whoever will win the Prada Series will be a serious competitor for the Cup.

- Every team has been radical with B2s, not only ETNZ. Making big changes on B2s is risky, they're not always improvements, and if a team change a lot maybe they weren't so happy about B1.

- Boats are crucial, but the ability of the crew is essential, and control system are a big part of the overall boat speed. Top speed won't win races, average speed is more important.

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