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sarah0809

Artemis?

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At present it looks like Artemis will be happy to go deeper and slightly slower than ETNZ and Luna Rosa. This will make them hard to defend against on the runs, and given the narrow race track, could rule the day. Deep= less gybes= less down speed time. Also gives them control of the inside of the course.

SHC

That's how I saw it, but didn't dare to say so because most on here take it as gospel when the ETNZ/LR guys tell us they go 10 degrees deeper than a non foiler! It seemed to me that with their rig and the fact they don't have to stay on foils (just keep the windward hull out), AR should be able to sail lower, even if ETNZ get better apparent wind angles through the extra speed. For me, the point is that nobody really knows how these boats will really compare when sailed against each other (yes, i know, I am astuck record on this! :D )

 

How much 'slower' than the foiler can you afford to give up? A couple percent, more, less? I agree the performance differences are not going to be really known until we see the boats together on the same patch of water.

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At present it looks like Artemis will be happy to go deeper and slightly slower than ETNZ and Luna Rosa. This will make them hard to defend against on the runs, and given the narrow race track, could rule the day. Deep= less gybes= less down speed time. Also gives them control of the inside of the course.

SHC

That's how I saw it, but didn't dare to say so because most on here take it as gospel when the ETNZ/LR guys tell us they go 10 degrees deeper than a non foiler! It seemed to me that with their rig and the fact they don't have to stay on foils (just keep the windward hull out), AR should be able to sail lower, even if ETNZ get better apparent wind angles through the extra speed. For me, the point is that nobody really knows how these boats will really compare when sailed against each other (yes, i know, I am astuck record on this! :D )

 

How much 'slower' than the foiler can you afford to give up? A couple percent, more, less? I agree the performance differences are not going to be really known until we see the boats together on the same patch of water.

 

Theortically both boats can head straight down wind if they want, albeit at about half their optimal VMGs :P (I'm just teasing, don't kill me).

 

However, with both boats sailing at optimal VMGs, we will presumably have to wait and see.

 

 

I still remember clearly how Alinghi 5 were constantly adjusting angle to make sure they kept one ama flying.

In contrast, BOR90/US17 seemed sooo much more powered up that this simply wasn't necessary.

 

Presumably ETNZ will be far more sensitive to changes in breeze (since they have to be careful not to fall off their foils), so are quite likely to sail a more conservative angle.

So perhaps we might see a similar situation with the foilers needing to manage their angles much more carefully.

 

But God only knows, I'm just a poor schmuck taking guesses and hoping like hell ETNZ have got it right and are bringing home the cup.

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Even realizing there is a long way to go, that ETNZ MoFo1.0 out there sailing probably its last blast today has a special place in my heart. Hard to know the wind angles it can achieve but the down-deep heartfelt angle has been really good.

 

If ETNZ do win this thing I hope that boat gets mounted somewhere on the Viaduct.

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Even realizing there is a long way to go, that ETNZ MoFo1.0 out there sailing probably its last blast today has a special place in my heart. Hard to know the wind angles it can achieve but the down-deep heartfelt angle has been really good.

 

If ETNZ do win this thing I hope that boat gets mounted somewhere on the Viaduct.

 

Past AC bridesmaids have been treated pretty shabbily in the past (NZL38 anyone?), so don't hold your breath.

To be honest, I can understand the ethos behind it. If GD can flog off NZL17 for a couple of mill to fund the next campaign (challenge or defence), then he will do it.

 

It is a shame to see these wonderful boats cast aside. However, it is sadly necessary.

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At present it looks like Artemis will be happy to go deeper and slightly slower than ETNZ and Luna Rosa. This will make them hard to defend against on the runs, and given the narrow race track, could rule the day. Deep= less gybes= less down speed time. Also gives them control of the inside of the course.

SHC

That's how I saw it, but didn't dare to say so because most on here take it as gospel when the ETNZ/LR guys tell us they go 10 degrees deeper than a non foiler! It seemed to me that with their rig and the fact they don't have to stay on foils (just keep the windward hull out), AR should be able to sail lower, even if ETNZ get better apparent wind angles through the extra speed. For me, the point is that nobody really knows how these boats will really compare when sailed against each other (yes, i know, I am astuck record on this! :D )

GD also tells you that they had 32knots VMG and 43knots in a straight line over a 10nm stretch ..

 

The best known foil assist was the Oracle tri at Valencia which did 33knots on a reach ..

 

Given the variables like stronger winds for ETNZ and the additional size and power of the tri it seems that foil assist may lose this one ..

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At present it looks like Artemis will be happy to go deeper and slightly slower than ETNZ and Luna Rosa. This will make them hard to defend against on the runs, and given the narrow race track, could rule the day. Deep= less gybes= less down speed time. Also gives them control of the inside of the course.

SHC

That's how I saw it, but didn't dare to say so because most on here take it as gospel when the ETNZ/LR guys tell us they go 10 degrees deeper than a non foiler! It seemed to me that with their rig and the fact they don't have to stay on foils (just keep the windward hull out), AR should be able to sail lower, even if ETNZ get better apparent wind angles through the extra speed. For me, the point is that nobody really knows how these boats will really compare when sailed against each other (yes, i know, I am astuck record on this! :D/> )

GD also tells you that they had 32knots VMG and 43knots in a straight line over a 10nm stretch ..

 

The best known foil assist was the Oracle tri at Valencia which did 33knots on a reach ..

 

Given the variables like stronger winds for ETNZ and the additional size and power of the tri it seems that foil assist may lose this one ..

-----------------------

Best known foil assist* was Banque Populaire V on her round the world record @ 41 knots. BP5 uses a curved lifting foil in each ama. In the ocean! In waves. Flying two hulls.

 

* unless, of course you think Sail Rocket with her single lifting(down) foil was "foil assist"!

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At present it looks like Artemis will be happy to go deeper and slightly slower than ETNZ and Luna Rosa. This will make them hard to defend against on the runs, and given the narrow race track, could rule the day. Deep= less gybes= less down speed time. Also gives them control of the inside of the course.

SHC

That's how I saw it, but didn't dare to say so because most on here take it as gospel when the ETNZ/LR guys tell us they go 10 degrees deeper than a non foiler! It seemed to me that with their rig and the fact they don't have to stay on foils (just keep the windward hull out), AR should be able to sail lower, even if ETNZ get better apparent wind angles through the extra speed. For me, the point is that nobody really knows how these boats will really compare when sailed against each other (yes, i know, I am astuck record on this! :D/> )

GD also tells you that they had 32knots VMG and 43knots in a straight line over a 10nm stretch ..

 

The best known foil assist was the Oracle tri at Valencia which did 33knots on a reach ..

 

Given the variables like stronger winds for ETNZ and the additional size and power of the tri it seems that foil assist may lose this one ..

-----------------------

Best known foil assist* was Banque Populaire V on her round the world record @ 41 knots. BP5 uses a curved lifting foil in each ama. In the ocean! In waves. Flying two hulls.

 

* unless, of course you think Sail Rocket with her single lifting(down) foil was "foil assist"!

Fair cop .. I wonder what the extra length (48 feet) of Banque Populaire V is worth on a foil assist ?

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There might be small changes to the boat going on, or worse.

Thursday they came back in early

Fri-Sat-Sun-Mon-Tues no sailing.

Weather has not been a factor.

By my count only 7 days of sailing so far.

 

Weather hasn't been an issue other than the Golden Gate hasn't seen average breeze above 10 knots in that window

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The best known foil assist was the Oracle tri at Valencia which did 33knots on a reach ..

I think you are a bit down on the top speed of that boat (try changing one of the 3's for a 4 ). And you aren't even close with regard to other boats. Most of the boats that competed in The Race exceeded that by some way (maybe not Team Phillips!!) . Club Med averaged 35 knots for an hour on a few occasions and I know they saw at least 38 knots (just checked an old report) and am pretty sure they topped out at over 40. Playstation averaged 28.65 knots for 24 hours. While I accept these boats were far bigger, they were also far heavier and had far less efficient rigs.

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Fair cop .. I wonder what the extra length (48 feet) of Banque Populaire V is worth on a foil assist ?

 

Where do you get an extra 48ft for BP V from?

 

BP V is 130ft LOA. USA was 90ft LWL and LOA was 120ft plus.

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Foil assist BP V, averaged 32 knots to cross the Atlantic with a peak at 47 + knot. Simply amazing.

 

It will be interesting to watch what a smaller 70 ft cat like AR can do.

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Off topic .... but with these Vendee boats now routinely breaking the 500 nm a day mark (and thus going almost as fast as a Torben Grael + crew VOR70) it looks like the under-crewed mono might still have a future.

 

And raises doubts about the drama of having a Bruce Farr one-design VOR 65 footer.

 

The speed gains are all amazing (inc. Paul Larsen).

 

But we sort of expect multis to go fast.

 

So, in significant ways, the monos are dressed to impress.

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At present it looks like Artemis will be happy to go deeper and slightly slower than ETNZ and Luna Rosa. This will make them hard to defend against on the runs, and given the narrow race track, could rule the day. Deep= less gybes= less down speed time. Also gives them control of the inside of the course.

SHC

That's how I saw it, but didn't dare to say so because most on here take it as gospel when the ETNZ/LR guys tell us they go 10 degrees deeper than a non foiler! It seemed to me that with their rig and the fact they don't have to stay on foils (just keep the windward hull out), AR should be able to sail lower, even if ETNZ get better apparent wind angles through the extra speed. For me, the point is that nobody really knows how these boats will really compare when sailed against each other (yes, i know, I am astuck record on this! :D )

GD also tells you that they had 32knots VMG and 43knots in a straight line over a 10nm stretch ..

 

The best known foil assist was the Oracle tri at Valencia which did 33knots on a reach ..

 

Given the variables like stronger winds for ETNZ and the additional size and power of the tri it seems that foil assist may lose this one ..

 

Wrong. I was in an Oracle tender in late August '09 with Coutts, just the two of us and a driver. Was not as windy in the afternoon as it had been in the morning. We were pretty far offshore, and north, probably north of La Jolla. They were doing a reaching test, in probably 14-16 knots, and I can assure you, we were doing well over 40 for at least 10 miles. We were flat out, and could only stay even with 17, at best.

post-2060-0-38445400-1355279050_thumb.jpg

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Wrong. I was in an Oracle tender in late August '09 with Coutts, just the two of us and a driver. Was not as windy in the afternoon as it had been in the morning. We were pretty far offshore, and north, probably north of La Jolla. They were doing a reaching test, in probably 14-16 knots, and I can assure you, we were doing well over 40 for at least 10 miles. We were flat out, and could only stay even with 17, at best.

That boat looks like a heap of rubbish. Just look at the racking and the wake. It will never work properly and stands no chance of beating any other DOG type boat :D :D :D

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Off topic .... but with these Vendee boats now routinely breaking the 500 nm a day mark (and thus going almost as fast as a Torben Grael + crew VOR70) it looks like the under-crewed mono might still have a future.

 

And raises doubts about the drama of having a Bruce Farr one-design VOR 65 footer.

 

The speed gains are all amazing (inc. Paul Larsen).

 

But we sort of expect multis to go fast.

 

So, in significant ways, the monos are dressed to impress.

Ehum, E4's record is 599Nm/24 hrs. How can you say almost as fast? It's one hell of a difference in averaging 20,89 vs 24,95 kts over 24 straight hours.

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That boat looks like a heap of rubbish. Just look at the racking and the wake. It will never work properly and stands no chance of beating any other DOG type boat :D :D :D

 

you going into the

 

self-destructing sarcasm loop

 

too si?

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Today I was in Gothenburg at the Yacht Racing Design & Technology Symposium and World Yacht Racing Forum. A highlight: I heard JuanK and Manolo Ruiz talk about AC72 designs. Also picked up tidbits during the breaks. A few things I heard:

- The AC72s are going faster and deeper than expected, therefore the downwind legs will be under 6 min.

- There are discussions of doing more laps to make the races last longer, but it was not clear to me in those discussions: who has to agree to the race format

- Assume a foiler. You want to hit the line at speed (40kts?) and gybe at the first mark without touching down. But you have an opponent who may use the prestart to make that a bit tough to pull off. Not to mention judging time and distance to the line at 35-40 kts.

- Too few watts from the grinders to do everything you want with controls, so compromises will be made and bets will be placed on what is more important.

- Before the OTUSA capsize, ETNZ had a least one incident with both rudders out of the water

- With 2 races per day in SF, you really want different foils for the first and second race as the wind builds.

- Both JuanK and Manolo think that performance and maneuverability at non-foiling speed will determine who wins races.

- Both also agree that ETNZ has executed extremely well with their AC72 sailing program.

- Sailors need to understand the science behind the controls more than they do in soft sail boats, in order to make fast decisions during races

 

Now, given what we've seen of the boats, the expressed opinions of those 2 are not surprising.

 

I won't hazard any guesses at right answers but the right questions may be:

- will the issues of transient performance through maneuvers trump top end speed?

- what happens in the prestart when a foil assist boat does all it can to keep a foiler from foiling and starting at speed?

- how will the teams handle 2 races per day, with "light" wind for the first race and "heavy air" for the second? You will want different foils for the 2 races, but you'll have to make a choice...

 

The first few races of the LVC RR will be pretty entertaining, regardless of how close they are, as these questions get answered.

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That's top gossip right there, thanks Jack. :)

 

Aggressive tactics in the prestart could sure make a difference, they'd need to have been well thought out and practised, I don't see any particular form of boat having an advantage here,

I would have thought it came down more to system choices and then good teamwork.

 

Time on distance? It's match racing - so no prizes for being over right on the start gun, just for having an advantage over your competitor whenever it is you do decide to start.

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That's top gossip right there, thanks Jack. :)

 

Aggressive tactics in the prestart could sure make a difference, they'd need to have been well thought out and practised, I don't see any particular form of boat having an advantage here,

I would have thought it came down more to system choices and then good teamwork.

 

Time on distance? It's match racing - so no prizes for being over right on the start gun, just for having an advantage over your competitor whenever it is you do decide to start.

 

Remember the Race 1 start in AC33. Similar things could happen.

 

Great insider gossip, Jack.

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"Both JuanK and Manolo think that performance and maneuverability at non-foiling speed will determine who wins races."

 

How much wind do TNZ and LR need to foil, 12 knot ? 15 knots ?

 

Does JK think that races will be under that level more than 50% of the time?

 

That seems pretty strange, unless it is a piece of psychological warfare.

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"Both JuanK and Manolo think that performance and maneuverability at non-foiling speed will determine who wins races."

 

That seems pretty strange, unless it is a piece of psychological warfare.

:lol:

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Perhaps he meant when boat speed was constrained below foiling speed, ie. due to pre-start manoeuvring?

 

It's not 100% clear is it?

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For sure a semi foiler will try to prevent his competitor from flying in the prestart but the first leg is a reach and as soon as the foiler flies. I think that the foiler could even let the non foiler start first and pass him in the first leg, before the mark. It will be interesting to see.

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Artemis is out. Watched them do a fly by on oracle base and 3rd street/bayview boat club before heading back to the other side of the South Bay. Considering the light wind they were really moving. Too far away to see much. Took some shitty Iphotos if anyone knows the code to drop them in. Oracle had a tender but was really far back.

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Perhaps he meant when boat speed was constrained below foiling speed, ie. due to pre-start manoeuvring?

And/or upwind? Agreed, not clear.

 

The WYRF site says they intend to put transcripts up of all the talks, by the end of the week.

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I think the situation is pretty easy for the foiler. there is no need to get to focused on the pre start because the foiler is fine starting behind the foil assister. Worst case scenario, the foiler is still trailing the foil assister at mark #1, and then what happens?

 

Lets use to shortnames to make it easier, LR=foiler, AR = foil assister.

 

There is two possible outcomes:

1 - AR continues on starboard tack, LR foils through the gybe and we have a split. There is no chance that AR can follow and gybe underneath. If LR sails to the boundary and gybes back in they will either cross clear ahead or use their starboard right of way.

AR - GAME OVER.

 

1 - AR gybes around mark # 1 and LR continues straight. Due to the double gybes that AR have to make before they meet and LR´s significantly faster full-speed foiling gybe, LR will cross clear ahead when the get back in to the middle of the course from the boundaries.

AR - GAME OVER.

 

Anyone thinking that you can match race away 6 knots better VMG is nuts and I am sure JK also understand this.

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Maybe he understands it now that it's been demonstrated to him, maybe not - but it's apparently not what he's saying

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I think the situation is pretty easy for the foiler. there is no need to get to focused on the pre start because the foiler is fine starting behind the foil assister. Worst case scenario, the foiler is still trailing the foil assister at mark #1, and then what happens?

 

Lets use to shortnames to make it easier, LR=foiler, AR = foil assister.

 

There is two possible outcomes:

1 - AR continues on starboard tack, LR foils through the gybe and we have a split. There is no chance that AR can follow and gybe underneath. If LR sails to the boundary and gybes back in they will either cross clear ahead or use their starboard right of way.

AR - GAME OVER.

 

1 - AR gybes around mark # 1 and LR continues straight. Due to the double gybes that AR have to make before they meet and LR´s significantly faster full-speed foiling gybe, LR will cross clear ahead when the get back in to the middle of the course from the boundaries.

AR - GAME OVER.

 

Anyone thinking that you can match race away 6 knots better VMG is nuts and I am sure JK also understand this.

 

Excuse me!!! Where did you get the 6 knots better VMG figure from. Your delusional if you think it will be anything like that.

 

What do you think is going to happen up wind then Nostradamus??? Im pretty sure foiling upwind is out of the question.

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104gcup.jpg

 

Had to wait to get home, still havent figured out how to post form a phone.

Like I said shitty iphoto. But since they are based in Alameda, us here in SF dont really get that much of a view of them usually unless you got a telescope.

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I think the situation is pretty easy for the foiler. there is no need to get to focused on the pre start because the foiler is fine starting behind the foil assister. Worst case scenario, the foiler is still trailing the foil assister at mark #1, and then what happens?

 

Lets use to shortnames to make it easier, LR=foiler, AR = foil assister.

 

There is two possible outcomes:

1 - AR continues on starboard tack, LR foils through the gybe and we have a split. There is no chance that AR can follow and gybe underneath. If LR sails to the boundary and gybes back in they will either cross clear ahead or use their starboard right of way.

AR - GAME OVER.

 

1 - AR gybes around mark # 1 and LR continues straight. Due to the double gybes that AR have to make before they meet and LR´s significantly faster full-speed foiling gybe, LR will cross clear ahead when the get back in to the middle of the course from the boundaries.

AR - GAME OVER.

 

Anyone thinking that you can match race away 6 knots better VMG is nuts and I am sure JK also understand this.

 

Excuse me!!! Where did you get the 6 knots better VMG figure from. Your delusional if you think it will be anything like that.

 

What do you think is going to happen up wind then Nostradamus??? Im pretty sure foiling upwind is out of the question.

I have done some geometry on the race course for LV Cup, and it looks like it will be a minimum of three gybes with a down wind angle of 150 degrees, and two gybes with a down wind angle of 160 degrees.

 

I will now continue the polar speculation with a few more assumptions:

 

Foiling:

Bear away at top mark is 20 kts VMG average during 20 seconds

the VMG through the gybe is averaging 20 kts, and the gybe duration is 20 seconds.

 

Non foiling:

Bear away at top mark is 20 kts VMG average during 20 seconds

the VMG through the gybe is averaging 15 kts, and the gybe duration is 25 seconds.

 

Results on the race course: (TWS 20 kts)

 

Foiling:

Boat speed 40 kts @ 160 deg

Downwind course = 3 nm = 5556 m

Bear away at top mark, 20 sec with 20 kts VMG = 206 m

Two gybes, 20 sec each with 20 kts VMG = 412 m

4938 m @37.5 kts VMG = 256 seconds

Net distance = 5556 m

Net time = 316 s 44(5 min 16 s)

Net VMG = 17.6 m/s = 34.2 kts

 

Non foiling:

Boat speed 36 kts @ 150 deg

Downwind course = 3 nm = 5556 m

Bear away at top mark, 20 sec with 20 kts VMG = 206 m

Three gybes, 25 sec each with 15 kts VMG = 580 m

4770 m @31.2 kts VMG = 298 seconds

Net distance = 5556 m

Net time = 393 s (6 min 33 s)

Net VMG = 17.6 m/s = 27.5 kts

 

So the net VMG gain is 6.7 knots down wind for the foiler, and it will lead by 1 min 17 s at the bottom gate. (ignoring the reaching start leg).

 

Second leg, beat nr 1:

The foiling boat will have a boat speed of 20 kts in the 20 kts breeze and a TWA of 40 deg which gives a AWA of 20 deg and a VMG of 15.3 kts.

I will not considder tacks this time around.

 

Foling: 3 nm/15.3 kts = 705 s (11 min 45 s)

To catch up, the non foiler needs to do the leg in 705-77 s = 628 s

5556/628 = 17.2 kts VMG.

 

 

1.9 kts better upwind VMG could be achieved by sailing 2 kts faster & 2 degrees higher, which also give an AWA of only 18 deg.

This is, in my opinion, to large of an upwind edge achievable in real life.

 

post-68342-0-80967300-1355097523_thumb.jpg

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And it just gets worse for the foil assister considering the course format, just look at the numbers:

 

Lets do the calcs for a 2 lap course. 3 downwinds & 2 upwinds, still neglecting the start and finish stretches.

 

3 downwinds will give an advantage of 77*3 = 231 s. This has to be made up for on the 2 upwinds by the non-foiler, which means 116 s per upwind

 

Foling: 3 nm/15.3 kts = 705 s (11 min 45 s)

To catch up, the non foiler needs to do the leg in 705-116 s = 589 s

5556/589 = 18.3 kts VMG.

 

So now, the non-foiler needs 3 kts higher VMG upwind. - That is 20 % better performance than the foiler.

3 kts VMG could be achieved by going 3 knots faster and 3 degrees higher, which also gives an AWA of 17.2 degrees....

 

No kidding Dalts knew this when he expressed non-foilers are in trouble.

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I think the situation is pretty easy for the foiler. there is no need to get to focused on the pre start because the foiler is fine starting behind the foil assister. Worst case scenario, the foiler is still trailing the foil assister at mark #1, and then what happens?

 

Lets use to shortnames to make it easier, LR=foiler, AR = foil assister.

 

There is two possible outcomes:

1 - AR continues on starboard tack, LR foils through the gybe and we have a split. There is no chance that AR can follow and gybe underneath. If LR sails to the boundary and gybes back in they will either cross clear ahead or use their starboard right of way.

AR - GAME OVER.

 

1 - AR gybes around mark # 1 and LR continues straight. Due to the double gybes that AR have to make before they meet and LR´s significantly faster full-speed foiling gybe, LR will cross clear ahead when the get back in to the middle of the course from the boundaries.

AR - GAME OVER.

 

Anyone thinking that you can match race away 6 knots better VMG is nuts and I am sure JK also understand this.

 

Excuse me!!! Where did you get the 6 knots better VMG figure from. Your delusional if you think it will be anything like that.

 

What do you think is going to happen up wind then Nostradamus??? Im pretty sure foiling upwind is out of the question.

I have done some geometry on the race course for LV Cup, and it looks like it will be a minimum of three gybes with a down wind angle of 150 degrees, and two gybes with a down wind angle of 160 degrees.

 

I will now continue the polar speculation with a few more assumptions:

 

Foiling:

Bear away at top mark is 20 kts VMG average during 20 seconds

the VMG through the gybe is averaging 20 kts, and the gybe duration is 20 seconds.

 

Non foiling:

Bear away at top mark is 20 kts VMG average during 20 seconds

the VMG through the gybe is averaging 15 kts, and the gybe duration is 25 seconds.

 

Results on the race course: (TWS 20 kts)

 

Foiling:

Boat speed 40 kts @ 160 deg

Downwind course = 3 nm = 5556 m

Bear away at top mark, 20 sec with 20 kts VMG = 206 m

Two gybes, 20 sec each with 20 kts VMG = 412 m

4938 m @37.5 kts VMG = 256 seconds

Net distance = 5556 m

Net time = 316 s 44(5 min 16 s)

Net VMG = 17.6 m/s = 34.2 kts

 

Non foiling:

Boat speed 36 kts @ 150 deg

Downwind course = 3 nm = 5556 m

Bear away at top mark, 20 sec with 20 kts VMG = 206 m

Three gybes, 25 sec each with 15 kts VMG = 580 m

4770 m @31.2 kts VMG = 298 seconds

Net distance = 5556 m

Net time = 393 s (6 min 33 s)

Net VMG = 17.6 m/s = 27.5 kts

 

So the net VMG gain is 6.7 knots down wind for the foiler, and it will lead by 1 min 17 s at the bottom gate. (ignoring the reaching start leg).

 

Second leg, beat nr 1:

The foiling boat will have a boat speed of 20 kts in the 20 kts breeze and a TWA of 40 deg which gives a AWA of 20 deg and a VMG of 15.3 kts.

I will not considder tacks this time around.

 

Foling: 3 nm/15.3 kts = 705 s (11 min 45 s)

To catch up, the non foiler needs to do the leg in 705-77 s = 628 s

5556/628 = 17.2 kts VMG.

 

 

1.9 kts better upwind VMG could be achieved by sailing 2 kts faster & 2 degrees higher, which also give an AWA of only 18 deg.

This is, in my opinion, to large of an upwind edge achievable in real life.

 

post-68342-0-80967300-1355097523_thumb.jpg

 

Some fairly Big assumptions made there dont you think? Eg Downwind angles. Please explain how a boat moving faster through the water downwind, as you assume, is going to run 10 degrees deeper.

 

In my world the wind goes forward as you speed, up meaning running 10 degrees deeper is highly unlikely.

 

All im trying to point out is that your figures are pure speculation. Plucking a figure of 6 knots Better VMG out of the air by making baseless asumptions is ridiculous.

 

Scince you like maths so much how bout you swap the downwind angle around and see what you get. A more likely scenario IMO.

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These numbers are of course speculations and should be taken for what they are. Nothing more, nothing less. What I would like to do is raise som speculation on what angles and speeds the boats are likely to do - hence their polars. I brought up this issue in the AC72 Polar bear-thread.

 

The big assumptions are based on the interview given by Franck Cammas the other day.

From my own experience racing windsurfers and 49ers, I would say that it is a fair assumption that you have a deeper downwind angle the faster you go. How much remains to be seen. I also think that we have been seeing from photos that the shape of the downwind head sails are too full near the front stay when foiling (you can see them backwinding a bit). Maybe an early indication that the AWA under foil is actually smaller than what they designed the sails for, which again indicates that the foilers go pretty deep down wind.

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^ It's a great subject for sure.

 

Fwiw OR's Burns said at Oracle World the downwind gains from foiling were 5 to 7 knots but unfortunately didn't say anything about the down-angle difference, which must surely be deeper the faster it can go as you surmise.

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Looking at how they are putting the wing up it is readily apparent they have never done it in strong let alone moderate winds.

 

Ask the LR boys how much these kick and buck in the wind, braking a shin bone with ease.

 

I saw the ETNZ wing bucking and rearing violently in the wind.

 

These guys need to get their systems sorted out before some one gets hurt. Not enough restraining lines and too many guys close to the wing foot.

 

Maybe so, but they are using the Paul Bieker counterweight (aluminum tank ahead of wing bottom, larger version of what's being used on AC45s) which is supposed to stabilize the thing

5cj382.jpg

 

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And it just gets worse for the foil assister considering the course format, just look at the numbers:

 

Lets do the calcs for a 2 lap course. 3 downwinds & 2 upwinds, still neglecting the start and finish stretches.

 

3 downwinds will give an advantage of 77*3 = 231 s. This has to be made up for on the 2 upwinds by the non-foiler, which means 116 s per upwind

 

Foling: 3 nm/15.3 kts = 705 s (11 min 45 s)

To catch up, the non foiler needs to do the leg in 705-116 s = 589 s

5556/589 = 18.3 kts VMG.

 

So now, the non-foiler needs 3 kts higher VMG upwind. - That is 20 % better performance than the foiler.

3 kts VMG could be achieved by going 3 knots faster and 3 degrees higher, which also gives an AWA of 17.2 degrees....

 

No kidding Dalts knew this when he expressed non-foilers are in trouble.

 

OK, for a start there are the same number of upwinds as downwinds, not 2 up 3 down.

 

Second, while I dont believe a complete non-foiler has a chance due to the downwind disadvantage, in the case of Oracle, you wouldn't be comparing ETNZ's downwind performance to a non-foiler, but to a foiler that may not be quite as efficient on the downwind legs. So maybe the VMG advantage for ETNZ would be 1-2 knots better downwind, in which case Oracle would need to be about half that VMG advantage (say 0.5 to 1knt) better upwind to match around the course. So I dont think ETNZ has as big an advantage as is commonly imagined.

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^ It's a great subject for sure.

 

Fwiw OR's Burns said at Oracle World the downwind gains from foiling were 5 to 7 knots but unfortunately didn't say anything about the down-angle difference, which must surely be deeper the faster it can go as you surmise.

 

If you reduce drag by foiling than you'll go deeper. There is no trade-off. If you're increasing drag as you go faster (which is what happens if you're not foiling) then you'll have to maintain your angle to generate enough power to keep your speed up. Because foiling reduces drag at high speeds, the foiling boat will have the potential to go deeper and faster. That doesn't mean it will win, as there are many other factors involved, but it is a huge advantage.

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And it just gets worse for the foil assister considering the course format, just look at the numbers:

 

Lets do the calcs for a 2 lap course. 3 downwinds & 2 upwinds, still neglecting the start and finish stretches.

 

3 downwinds will give an advantage of 77*3 = 231 s. This has to be made up for on the 2 upwinds by the non-foiler, which means 116 s per upwind

 

Foling: 3 nm/15.3 kts = 705 s (11 min 45 s)

To catch up, the non foiler needs to do the leg in 705-116 s = 589 s

5556/589 = 18.3 kts VMG.

 

So now, the non-foiler needs 3 kts higher VMG upwind. - That is 20 % better performance than the foiler.

3 kts VMG could be achieved by going 3 knots faster and 3 degrees higher, which also gives an AWA of 17.2 degrees....

 

No kidding Dalts knew this when he expressed non-foilers are in trouble.

 

OK, for a start there are the same number of upwinds as downwinds, not 2 up 3 down.

 

Second, while I dont believe a complete non-foiler has a chance due to the downwind disadvantage, in the case of Oracle, you wouldn't be comparing ETNZ's downwind performance to a non-foiler, but to a foiler that may not be quite as efficient on the downwind legs. So maybe the VMG advantage for ETNZ would be 1-2 knots better downwind, in which case Oracle would need to be about half that VMG advantage (say 0.5 to 1knt) better upwind to match around the course. So I dont think ETNZ has as big an advantage as is commonly imagined.

 

You are incorrect on your first point. Excluding the start and and finish reaches, the Leg1 is a downwind leg and the final Leg is a downwind leg therefore there has to be one less upwind leg then downwind legs.

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A poster on another site claims to have seen them foil today, not for long but definately a foil.

I saw the same action from another vantage point (approx 3/4 mile away with binocs) and didn't think they got up on 1 foil. We both agree they crashed immediately. ymmv

If they did expect some cool video in the next couple of days.

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Just as one boat stops entertaining us.......

 

The other takes over.

 

Who would have thought it was Big Red!

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She looks like the leeward hull is sinking when they fly a hull. Juan K got the hull volume distribution wrong. All that weight on a single hull..... not enough bouyancy. Oh yeah, it's foil assist.

 

 

 

 

11385162981115371964.jpg

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^^

Agree, it didn't happen. The above (and other) photos show them using the same boards as before agreed by all to be nonfoiling boards.

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They look pretty much stuffed without foiling and all their trials are looking this way. Not sure how Messieurs Cayard, Esquier and JK are going to explain this to the boss? Ah, yes, I have it. Give us some more money!

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yeee-haaaaa - ride that bucking bull!

Someone needs to tell them that they need to hang on for more than 8 seconds.

 

Just add chop...

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I get some pretty different figures. To check my distances, I have drawn it up in cad. First, for simplicity, I am assuming both boats sail the same angles. That then allows people to make easy comparisons and to then change the figures as they believe is fit.

 

I have taken both boats sail upwind with an 80 degree tacking angle, while downwind they gybe through 30 degrees.

 

On 2 upwinds, the total distance sailed would be 9.334 nm

On 3 downwinds, the total distance sailed would be 9.317

 

Working it through, aboat doing the downwind legs at 40 knots boatspeed takes 13.98 minutes, a boat doing 5 knots takes 15.97 minutes, a difference of 2 minutes.

 

Upwind doing 20 knots, it would take 28 minutes to do the total distance. The boatspeed to do it 2 minutes slower is 18.66 knots.

 

OK, we then have to factor in the reaches which the RI says can be of different lengths. This means that, give or take, if a boat is 5 knots slower in a straight line downwind, it needs to be 2 knots quicker upwind.

 

Where this gets interesting is when each boat sails different angles. We have seen an unsupported claim by Franck Cammas that the foiler is faster and lower, yet there seems to be a suggestion that yesterday, ETNZ was lower than LR when not foiling. In addition, Steve Clark has suggested (as did I previously but at that time everybody said i know shit ;) ) that AR is set up to go lower and slower.

 

If ETNZ are 6 knots faster and 10 dgrees lower when foiling, it is probably a big ask to see that back upwind. If AR is, say, 5 knots slower but lower, it becomes more believable. A few degrees better angle upwind as well and it becomes a very interesting debate. I think about 2.5 degrees extra height (5 degrees tacking angle) and they can even go the same speed upwind and they are pretty well equal round the course.

 

I readily admit 2 things. 1, It is possible that i have screwed up my calcs (but not the distances sailed) and 2. I have made some base assumptions that some or even many won't agree with. The fact remains that nobody yet knows what the best foilers and non foilers can do.

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I get some pretty different figures. To check my distances, I have drawn it up in cad. First, for simplicity, I am assuming both boats sail the same angles. That then allows people to make easy comparisons and to then change the figures as they believe is fit.

 

I have taken both boats sail upwind with an 80 degree tacking angle, while downwind they gybe through 30 degrees.

 

On 2 upwinds, the total distance sailed would be 9.334 nm

On 3 downwinds, the total distance sailed would be 9.317

 

Working it through, aboat doing the downwind legs at 40 knots boatspeed takes 13.98 minutes, a boat doing 5 knots takes 15.97 minutes, a difference of 2 minutes.

 

Upwind doing 20 knots, it would take 28 minutes to do the total distance. The boatspeed to do it 2 minutes slower is 18.66 knots.

 

OK, we then have to factor in the reaches which the RI says can be of different lengths. This means that, give or take, if a boat is 5 knots slower in a straight line downwind, it needs to be 2 knots quicker upwind.

 

Where this gets interesting is when each boat sails different angles. We have seen an unsupported claim by Franck Cammas that the foiler is faster and lower, yet there seems to be a suggestion that yesterday, ETNZ was lower than LR when not foiling. In addition, Steve Clark has suggested (as did I previously but at that time everybody said i know shit ;) ) that AR is set up to go lower and slower.

 

If ETNZ are 6 knots faster and 10 dgrees lower when foiling, it is probably a big ask to see that back upwind. If AR is, say, 5 knots slower but lower, it becomes more believable. A few degrees better angle upwind as well and it becomes a very interesting debate. I think about 2.5 degrees extra height (5 degrees tacking angle) and they can even go the same speed upwind and they are pretty well equal round the course.

 

I readily admit 2 things. 1, It is possible that i have screwed up my calcs (but not the distances sailed) and 2. I have made some base assumptions that some or even many won't agree with. The fact remains that nobody yet knows what the best foilers and non foilers can do.

 

What is your true wind speed in all of this?

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Shall I explain the thought process?

Is (feature X) likely to produce a fast boat compared to the other (2 so far) designs? If not, does (feature X) offer some other race/development advantage?

If 'no' - to both questions :o:unsure:

 

But maybe ½ sunk, with wing flaps designed by a toddler is the way to go?

Time will tell.....

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Shall I explain the thought process?

Is (feature X) likely to produce a fast boat compared to the other (2 so far) designs? If not, does (feature X) offer some other race/development advantage?

If 'no' - to both questions :o:unsure:

 

The question is not what thought process you went through to arrive at these questions, but rather what factors lead you to conclude that the answer to both would be 'no'?

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Actually your question was: How do you (all) know what's fast? (and a still photo is fine to see the ugly gaps :lol:)

 

Do you think that arrangement of flaps (spoilers ;)) appears to be fast?

 

Leaving that aside for now, the factors used were based on - discussion, experience and wild guessing - the usual methods.

 

But actually I didn't reach a no/no conclusion, more like no/?

 

I'm still hoping someone will present the evidence for a race/development advantage - because that would give more hope of a competitive series next northern summer.

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These guys need to get their systems sorted out before some one gets hurt. Not enough restraining lines and too many guys close to the wing foot.

Maybe so, but they are using the Paul Bieker counterweight (aluminum tank ahead of wing bottom, larger version of what's being used on AC45s) which is supposed to stabilize the thing

 

The counterweight is an interesting solution.

 

I didn't realise the problem was our wing is too light and hoisting needs more time and people.

 

Heavier fluttering things are easier to manhandle than lighter fluttering things, right?

 

whats wrong with this picture

yeah, noticed that too

 

Uh oh, seems vaguely familiar. The kingpost- and arse-dragging looks new.

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I didn't realise the problem was our wing is too light and hoisting needs more time and people

 

<cough, cough>

 

It's counterweight: Basiliscus explained it a couple of times already, but the idea is to make the wing aerodynamically stable while suspended from the crane by bringing the CoG/axis of rotation ahead of the Center of Lift

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It's counterweight, and I would imagine all wings weigh the same 1,300 kg

 

Agreed. Strapping on a ton of water meets my critieria for counter. Speaking of weight, has Artemis' wing passed measurement yet?

 

Basiliscus explained it a couple of times, but the idea is to make the wing aerodynamically stable while suspended from the crane by bringing the CoG/axis of rotation ahead of the Center of Lift

 

Interesting. I didn't realise the wing remains perfectly vertical and feathered during hoisting. Alameda must have a very special type of wind vector that remains constant from zero to 40m above ground. Could this local phenomenon be caused by the mysterious brown haze seen in Artemis photos? ETNZ & LR photos lack this feature despite extensive HDR post-processing.

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Speaking of weight, has Artemis' wing passed measurement yet

 

There's only a minimum wing weight (plus CoG height), so no problem there - if anything, it's meeting maximum sailing weight for the boat.

 

Anyway, I imagine PB looking at these pictures and grumbling: "I'm spending €45M and all I get is to beat that?"

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The mid span flaps are not spoilers.

SHC

 

Thus the ;)

 

They are messy though don't you think

 

95802921613065543905.jpg

 

TAFV15P13_18.jpg

 

Which aspects of this design look promising?

Do any aspects of this design 'advance the art'?

Do any of the design choices look especially detrimental to performance to you?

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^^

The weather board looks quite similar to ARs also. Looks like they were testing more than the wing.back then.

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The mid span flaps are not spoilers.

 

How about these?

 

post-19376-0-26874300-1355422335_thumb.jpg

Those are poorly trimmed flaps,..................... that are likely spoiling someone's day.

 

B

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Big is sometimes smoking, sometimes arse dragging, sometimes nose diving...

 

see www.pressure-drop.us

 

Artemis Racing December 12 2012 - Erik Simonson- pressure-drop.us ©

Med_919792757166028477761.jpg

Artemis Racing December 12 2012 - Erik Simonson- pressure-drop.us ©

 

Artemis Racing December 12 2012 - Erik Simonson- pressure-drop.us ©

 

Artemis Racing December 12 2012 - Erik Simonson- pressure-drop.us ©

Med_206406919804657151231.jpg

Artemis Racing December 12 2012 - Erik Simonson- pressure-drop.us ©

 

67527261125047278159 - Erik Simonson- pressure-drop.us ©

 

Artemis Racing December 12 2012 - Erik Simonson- pressure-drop.us ©

Med_artemis%20racing%20Dec%20129.jpg

Artemis Racing December 12 2012 - Erik Simonson- pressure-drop.us ©

Med_artemis%20racing%20Dec%201210.jpg

Artemis Racing December 12 2012 - Erik Simonson- pressure-drop.us ©

 

Artemis Racing December 12 2012 - Erik Simonson- pressure-drop.us ©

Med_artemis%20racing%20Dec%20123.jpg

Artemis Racing December 12 2012 - Erik Simonson- pressure-drop.us ©

 

Artemis Racing December 12 2012 - Erik Simonson- pressure-drop.us ©

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I get some pretty different figures. To check my distances, I have drawn it up in cad. First, for simplicity, I am assuming both boats sail the same angles. That then allows people to make easy comparisons and to then change the figures as they believe is fit.

 

I have taken both boats sail upwind with an 80 degree tacking angle, while downwind they gybe through 30 degrees.

 

On 2 upwinds, the total distance sailed would be 9.334 nm

On 3 downwinds, the total distance sailed would be 9.317

 

Working it through, aboat doing the downwind legs at 40 knots boatspeed takes 13.98 minutes, a boat doing 5 knots takes 15.97 minutes, a difference of 2 minutes.

 

Upwind doing 20 knots, it would take 28 minutes to do the total distance. The boatspeed to do it 2 minutes slower is 18.66 knots.

 

OK, we then have to factor in the reaches which the RI says can be of different lengths. This means that, give or take, if a boat is 5 knots slower in a straight line downwind, it needs to be 2 knots quicker upwind.

 

Where this gets interesting is when each boat sails different angles. We have seen an unsupported claim by Franck Cammas that the foiler is faster and lower, yet there seems to be a suggestion that yesterday, ETNZ was lower than LR when not foiling. In addition, Steve Clark has suggested (as did I previously but at that time everybody said i know shit ;) ) that AR is set up to go lower and slower.

 

If ETNZ are 6 knots faster and 10 dgrees lower when foiling, it is probably a big ask to see that back upwind. If AR is, say, 5 knots slower but lower, it becomes more believable. A few degrees better angle upwind as well and it becomes a very interesting debate. I think about 2.5 degrees extra height (5 degrees tacking angle) and they can even go the same speed upwind and they are pretty well equal round the course.

 

I readily admit 2 things. 1, It is possible that i have screwed up my calcs (but not the distances sailed) and 2. I have made some base assumptions that some or even many won't agree with. The fact remains that nobody yet knows what the best foilers and non foilers can do.

 

Just home from Gothenburg (BTW, cold and dark this time of year. Brrr!)

 

Simon, when you use 40kts for downwind leg are you assuming 40kts all the time? Before, during and after gybes? Maybe a foiler is not at top speed all the time? Your calculations work out to 14 min for the downwind leg. Any assumptions about the time for the crew to furl/unfurl during gybes and time to furl / drop at the leeward mark?

 

Lots of interesting ideas here. But we won't really know until they line up in July...

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Jack

 

I have simply thrown in some figures to start the debate Depending on people's, beliefs, prejudices and/or fantacies, they can play with them as much as they like! What I hope this does is show that it isn't anywhere near as clear cut as others are trying tio make it, or put another way, it is meant to justify my extreem fence sitting position!! :D

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^

would that boat have survived or17's bear-away?

 

i don't think so...

 

they had better be bloody careful then

 

as unlike oracle

 

artemis DO have to race in the rougher weather window that the LVcup is in

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^^

 

That's what I meant, and it's torsion/racking rather than flex. I think it's worrisome because AR's connecting structure is designed to be very stiff until it suddenly collapses, unlike OR's that has the possibility of deformation built in. We already discussed this prior to AC33 for Alinghi 5

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^^

 

That's what I meant, and it's torsion/racking rather than flex. I think it's worrisome because AR's connecting structure is designed to be very stiff until it suddenly collapses, unlike OR's that has the possibility of deformation built in. We already discussed this prior to AC33 for Alinghi 5

You are right .. the twist in Artemis's platform is deliberate .. the mast supporting structure has ties supporting the king post and these can be adjusted to allow anything from zero twist to the maximum that the cross beams can stand ..

 

Why they are allowing the twist is one is another matter ..

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^^

 

That's what I meant, and it's torsion/racking rather than flex. I think it's worrisome because AR's connecting structure is designed to be very stiff until it suddenly collapses, unlike OR's that has the possibility of deformation built in. We already discussed this prior to AC33 for Alinghi 5

You are right .. the twist in Artemis's platform is deliberate .. the mast supporting structure has ties supporting the king post and these can be adjusted to allow anything from zero twist to the maximum that the cross beams can stand ..

 

Why they are allowing the twist is one is another matter ..

I will be interested to see the consequences of the windward bow digging in,...... when they bear away in 28 knots wind. :D

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