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      Abbreviated rules   07/28/2017

      Underdawg did an excellent job of explaining the rules.  Here's the simplified version: Don't insinuate Pedo.  Warning and or timeout for a first offense.  PermaFlick for any subsequent offenses Don't out members.  See above for penalties.  Caveat:  if you have ever used your own real name or personal information here on the forums since, like, ever - it doesn't count and you are fair game. If you see spam posts, report it to the mods.  We do not hang out in every thread 24/7 If you see any of the above, report it to the mods by hitting the Report button in the offending post.   We do not take action for foul language, off-subject content, or abusive behavior unless it escalates to persistent stalking.  There may be times that we might warn someone or flick someone for something particularly egregious.  There is no standard, we will know it when we see it.  If you continually report things that do not fall into rules #1 or 2 above, you may very well get a timeout yourself for annoying the Mods with repeated whining.  Use your best judgement. Warnings, timeouts, suspensions and flicks are arbitrary and capricious.  Deal with it.  Welcome to anarchy.   If you are a newbie, there are unwritten rules to adhere to.  They will be explained to you soon enough.  

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^ Thanks Rudder.

 

'Qualifiers' though? Semi finals, 'playoffs'....... if you must

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Yes, thanks Rudder.  NBC Sports apparently aren't showing this series here, now that USA isn't racing.  I can watch the official Am Cup online, but I have to use Hola and "watch it from Antarctica", or somewhere where the TV rights aren't locked up.  That works, but I really prefer to download your files  and watch it whenever I like.

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3 hours ago, Rudder_NZ said:

Qualifiers Day 1

NZ vs UK (Incomplete. See second NZ UK race for full replay)
https://drive.google.com/open?id=0BxIm00ZuX5lXd2p3UnlrVnVJMDA
 

Thx Rudder_NZ - really appreciate this.

Is the race 1 NZ/BAR the first part or second part of the 2nd race file?

Would like to see them in order if possible!

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2 minutes ago, Inshallah said:

Thx Rudder_NZ - really appreciate this.

Is the race 1 NZ/BAR the first part or second part of the 2nd race file?

Would like to see them in order if possible!

It's a few minutes in to the 2nd NZ vs UK race (The bottom of the video will say it is a replay in a grey bar at the bottom). I'm at work so cannot tell you the exact time stamp sorry. In this case watching them out of order might actually be more interesting. 

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2 hours ago, nav said:

^ Thanks Rudder.

 

'Qualifiers' though? Semi finals, 'playoffs'....... if you must

Your right. Next upload will be ChallengerSemis or something. 

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I bought the AC qualifier and playoff package ... now i cant watch replays anymore.

 

am I the only one with this problem?

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Hey Rudder,  Thanks from the fans who have to watch your downloaded files.  They are great, rewind check details, relive the exciting bits, Great.

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1 hour ago, VladTheImpaler said:

Rudder, this is fucking fantastic.

I can't imagine that the jackwagons at americascup.com would be thrilled to learn you're doing it.

The AC folks, if anyone there even pays attention, probably ~want~ people to be able to get the coverage, live or not.

The ONLY parties concerned about pirating would be the broadcasters (not ACEA) and the broadcasters have far bigger fish to fry than a relatively few people figuring out anarchistic workarounds. ACEA already got the money at some point, they simply wouldn't care what the broadcasters' various problems are now, torrents or otherwise.

 

 

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Great stuff ... but maybe we should all stop saying thank you Rudder.... that way we will not all get mega emails everyday and will just be able to enjoy some great sailing ... go Team NZ 

 

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8 hours ago, TimBits said:

Great stuff ... but maybe we should all stop saying thank you Rudder.... that way we will not all get mega emails everyday and will just be able to enjoy some great sailing ... go Team NZ

Or you could change your settings to stop the emails.

Thanks again Rudder!

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Rudder_NZ: Thank you very much for these replays! Struck as German in Italy and Servus TV kicks me out here from the livestream from Bermuda so I am very happy to watch the replays provided by you! Cheers from South Tyrol

 

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Challenger Playoffs day 2

Race1 - Sweden vs Japan
https://drive.google.com/open?id=0BxIm00ZuX5lXaGdBa0RzSHpXLVk

Race2 - NZ vs UK (Sorry I missed the first few legs. Was so nervous I didn't notice I wasn't recording.)
https://drive.google.com/open?id=0BxIm00ZuX5lXb284TE9jZlVHLTA

Race3 - SWEDEN vs JAPAN
https://drive.google.com/open?id=0BxIm00ZuX5lXeFp4akZTcExwbDQ

Race4 - NZ vs UK
https://drive.google.com/open?id=0BxIm00ZuX5lXNnQ5WTYyd1Vzbms

Looks like SailingAnarchy is under too much load so I cannot attach the torrent. Here is a link to the torrent instead.
https://drive.google.com/open?id=0BxIm00ZuX5lXUmV2cWV0MDA0Tlk

ChallengerPlayoffDay2.torrent

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I can't thank you enough for these, Rudder!  Appreciate it so much!  

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@Rudder_NZ

Once again thank you.

Watched it live but had to turn the sound off due to commentary.  But I have to watch that all again tonight.

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8 minutes ago, Hitchhiker said:

Thanks Rudder.  I had not realized that NBCSN had dropped coverage.  Cheers mate!

Challenger finals will be on broadcast NBCSN starting 6/10, and the AC Finals on NBC/NBCSN starting 6/17. And if you have a legit NBCSN subscription, you can watch the Challenger semis live or replay on the NBC Sports app now.

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Again, my most profound thanks to Rudder_NZ for these Google Drive links.  Without them, I would have no way at all to watch the races, and they are a lot of fun to watch!

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On 31/5/2017 at 9:48 AM, Inshallah said:

BTW - the BAR/TF crash did make some free to air news!!!!!!! Crashes and scandal - that's what is considered news worthy here!!!!!!

The ABC just proved you right this morning. The very first and only mention I've seen of the America's Cup happening on FTA Oz TV happened this monring. They actually showed 10secs of footage of... you guessed it... NZ capsizing. They didn't piggyback any other information on the back of that however. Nothing. No results or anything like that. They didn't even mention who NZ were racing when they crashed, or how it happened or anything to explain the vision at all. In fact it was so embarrassingly bad, it took the presenters throwing to the weather presenter who gave them the proper "capsize" terminology to describe what the VT was showing.

Up until then, the best they could come up with was to describe NZ as having "gone vertical" with the expert observation that it isn't fast sailing a boat like that. This is a little window into the staggering depth & quality of Australian sports media broadcasting.

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yes amazing if it Ain't Footy they don't care 

 well done guys ... hopefully they will get it all done and get back out there tomorrow for anther crack at BAR ... looks like you may have run into BAR's foil turbulence under water and just lost your lift ... that is a danger in these conditions ... just like planes coming in to land behind another jet get "wingtip turbulence" and fall out of the sky ... foiling yachts can do the same thing under the water ... you just don't see it and nor did PB https://en.wikipedia.org/wiki/Wake_turbulence

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Am I right in supposing that the wings on the tips of the rudders are actually pulling the stern of the boat down to counteract the moment of the main wing driving the top forwards? There is virtually no technical analysis of how the boats actually work provided in the coverage. Even very basic info like this seems to be a state secret.

If that's the case, then once you nose dive past the point of the rudder wings being deep enough in the water to not be cavitating, then you're pretty much gone for all money no matter what you do. At that point you're relying totally on the minimal buoyancy in the extremely slimline bows.

If that's correct, then ETNZ had two problems. No speed going forwards to produce the required downforce at the rudders to stop them coming out of the water + no wing effect at all once they had left the water. No way back from there. I hate to say it, but Ben Ainslie successfully put them into that position.

 

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1 minute ago, ryanmoreton said:

Which race did ETNZ put it in the tide? a bit irrelevant but keen to give it a look

The last one of the day I think. Race 4

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this best shows how they work 

the main foils rotate for and aft to give different degrees of lift ... they also can rotate side to side ... to give different sailing modes ( how they hell they do the mechanics of this I don't know and take mega tons of load)

the foiling rudders also can rotate for and aft to give down force or uplift ... so the windward rudder is creating more down force than the lea .... to keep the boat down and take the forward force from the sail ...the lea rudder is balancing the boat on the foil so at a different angle .... the trick is to keep the boat at the right height out of the water .... in light airs and going down wind you need lest of the foil in the water as the side force that is taken by the straight dagger board section of the foil is what stops the side force from the wind through the wing....but in lighter air you need to be very careful as if the foil gets to close to the surface if with suck air down from the surface and lose all the lift .... in heavy air , like today, you will have noticed that the boats are sailing closer to the water ... so harder to keep the hulls out all the time... also got to be careful not to "stall" the foil and also fall off it .... today it looks like they sailed right into BAR's disturbed water flow which would have had both sideways vortices in it plus it could have also have had air bubbles  and Team NZ's foil just lost it's lift .... dived and the rudders  both came out of the water , nose in and the rotation of the wing  doing 20 kn , way up above them, would just pull the boat over into a pitch pole ......not sure why they sail "nose down" all the time but I guess that is to change the angle of the wing ( sail ) to the wind .... and I have never understood the "inverted" shape of the bow ... just seems wrong for a sail boat as it would give very little lift out of the water in a nose dive ... but it may be more about it's aerodynamics in air when foiling than when in the water ..... anyway that is my engineering take on it all ... I stand corrected if anyone can add to this .... but it is amazing stuff ... lets hope tomorrow is a better day or the race day see sense and postpone when it is so on the edge 

 

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Frack.  Its saying there have been too many google downloads and I can't watch the race #4 (UK/NZ).  WTF???  Why does god hate me so!!!!

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Rudder_NZ, racing is abandoned today, so get some well deserved sleep.  But, if you do get a chance, can you record race 2 in full.  That's if they are replaying the races from yesterday.

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The Americas Cup (and the fan base) owes a huge debt of gratitude to Rudder.

It is astonishing to me that we depend on a skilled fan circulating these high quality replays, which are unavailable from professional or commercial sources.

.

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I cannot agree with Mambo Kings strongly enough.  I would have happily paid to watch the races, but that option was simply not made available to me.  I don't understand the commercial thinking behind that decision.  I also watch indoor rock climbing competitions, which are simply streamed on a pay site, which works perfectly.   The organizers of such events know that there are not going to get a cable or over-the-air channel to carry the event, so they just do the logical thing (stream it on a pay site) and everyone is happy.

And so, I too, cannot thank Rudder_NZ enough for his GoogleDrive links.

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15 hours ago, TimBits said:

 I have never understood the "inverted" shape of the bow ... just seems wrong for a sail boat as it would give very little lift out of the water in a nose dive ... but it may be more about it's aerodynamics in air when foiling than when in the water ..... anyway that is my engineering take on it all ... I stand corrected if anyone can add to this 

The "inverted" bow shapes are a fairly recent innovation in modern catamarans. Known as "wave piercing" the concept is to better shed water off the forward bow sections when burying in waves and to reduce hobby-horsing the boat in even smaller waves. And on these super high speed foilers, you get added benefits of lower windage from the bows. 

The classic design of the Tornado hull (from 1968) has an almost flat forward deck....with a pretty big "V" wedge cross sectional shape to maximize forward volume....the concept being to keep the deck above the water line as much as possible. Basically the opposite compared to wave-piercing hulls.

Obviously, inverted bows are no guarantee for preventing pitch poles.

 

 

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Just wondering, Ian Murray believes ETNZ's 2nd damaged Wing  was their preferred appendage. I thought the Wing & Hull are the 2 'one design' components that are identical on each boat, and can't be changed.

Will someone please clarify this for me.   

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10 minutes ago, gnelson said:

Just wondering, Ian Murray believes ETNZ's 2nd damaged Wing  was their preferred appendage. I thought the Wing & Hull are the 2 'one design' components that are identical on each boat, and can't be changed.

Will someone please clarify this for me.   

The only part of the wing that is one design is the structural part.  Otherwise all system that control wing trim and how it function is prototype.

 

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I think they are allowed 2 wings .... 4 sets of foils ... I think the shape and size of the wing is the same but how it's constructed and how it is flexed and reshaped during sailing is each boats design..

Hulls as i understand it are all the same size shape and weight 

thanks Tornado for the bow shape explanation .. makes sense but still to a mono hull sailer looks wrong ....and sure does not help in a pitch pole ... you would think that as these boats are above the water 99% of the time you would not need a wave piercing hull shape and the classic V under would be better to keep the nose when they drop off the foils which seems to happen a lot

 nothing would really other that some form of air bag up front that goes off it the boat goes over 40o or so forward but the G forces of it stopping would most likely tear the boat apart and the mast off ...

Great to see they have filled the top of the sail with foam but does not do the skin much good -:)

this should be good to counter act global warming as they are using up all this carbon -:) 

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17 minutes ago, Coconuts.is said:

The only part of the wing that is one design is the structural part.  Otherwise all system that control wing trim and how it function is prototype.

 

 

The only part of the wing that is one design is the shape (or surface if you prefer)

 

15 minutes ago, TimBits said:

I think they are allowed 2 wings .... 4 sets of foils ... I think the shape and size of the wing is the same but how it's constructed and how it is flexed and reshaped during sailing is each boats design..

Hulls as i understand it are all the same size shape and weight 

thanks Tornado for the bow shape explanation .. makes sense but still to a mono hull sailer looks wrong ....and sure does not help in a pitch pole ... you would think that as these boats are above the water 99% of the time you would not need a wave piercing hull shape and the classic V under would be better to keep the nose when they drop off the foils which seems to happen a lot

 nothing would really other that some form of air bag up front that goes off it the boat goes over 40o or so forward but the G forces of it stopping would most likely tear the boat apart and the mast off ...

Great to see they have filled the top of the sail with foam but does not do the skin much good -:)

this should be good to counter act global warming as they are using up all this carbon -:) 

2 wing spars, unlimited flaps, seals etc

4 foils, not 4 'sets'

wing floatation is mandated in the Rule

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well by 4 foils I mean 4 shapes ... so a set is a pair  so 4 pairs ... well thats how the Japan vid above explained it 

this is a great video 

 

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18 minutes ago, TimBits said:

 

thanks Tornado for the bow shape explanation .. makes sense but still to a mono hull sailer looks wrong ....and sure does not help in a pitch pole ... you would think that as these boats are above the water 99% of the time you would not need a wave piercing hull shape and the classic V under would be better to keep the nose when they drop off the foils which seems to happen a lot

 nothing would really other that some form of air bag up front that goes off it the boat goes over 40o or so forward but the G forces of it stopping would most likely tear the boat apart and the mast off ...

Great to see they have filled the top of the sail with foam but does not do the skin much good -:)

this should be good to counter act global warming as they are using up all this carbon -:) 

Yes the faster you go, the less you can do to prevent "lawn darting" the bows...regardless of fancy shaping. 

In "traditional" catamaran displacement sailing wave piercing can help to resist pitching moment up to a point, but then the angles/drag forces take over and you are done. The Tornado suffers the same fate...but may do better in certain sea states then pierces and vis versa. It's all a compromise.

 

 

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In displacement cat sailing, wave piercers seem better suited in lighter to moderate air where smaller waves may tend to cause minor fore/aft pitching in "V" bows....less pitching means more efficient forward motion. better air flow over the sail plan...that is where they are better off.

 

 

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17 minutes ago, TimBits said:

well by 4 foils I mean 4 shapes ... so a set is a pair  so 4 pairs ... well thats how the Japan vid above explained it 

this is a great video 

 

Thanks for the video.

Still only allowed 4, four, 1,2,3,4, '1 more than three', ACC foils though...

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Ok I was quoting from 3.55 in this japan vid  which says they make 6 different boards but are only allowed to keep 4 for the AC ... but as they are all different that must mean pairs as no one is going to run two different board shapes at once ?

 

 

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5 minutes ago, TimBits said:

Ok I was quoting from 3.55 in this japan vid  which says they make 6 different boards but are only allowed to keep 4 for the AC ... but as they are all different that must mean pairs as no one is going to run two different board shapes at once ?

 

 

:o I'm done, someone else can sort you out.....

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Ok I see where the misunderstand comes from they are allowed 6 ie 3 pairs but the 3rd pair are spares that they can use if they damage one of the 1st or 2nd  ...

So the video from Team Japan is incorrect ... sorry about that... I would have thought they would have know what they were talking about 

"Teams are only permitted to build four daggerboards for their new America’s Cup Class boats – in other words just two sets.

Most teams have elected to build one pair that is geared towards heavier winds – smaller boards, less lift, less drag, higher potential top speed; and one set that will perform better in lighter conditions – bigger boards, more lift, but more drag and more limited top speed.

Rationale: 
Boards can be damaged by (for example) hitting a large piece of marine debris, or they can break through poor execution of a maneuver faulty design and engineering and/or a flaw in the construction process.

Some of the teams training in Bermuda for the 35th America’s Cup have damaged their boards when they unintentionally hit objects in the water. As a result, those teams were in favor of allowing replacement boards. It seemed to most, with the foils being such a critical component of the boats, that it would be ridiculous to have the result of the 35th America’s Cup influenced by such an unfortunate and largely uncontrollable situation.

Notwithstanding the limit on building four new America’s Cup Class daggerboards, the teams discussed making a Protocol amendment beginning in June 2016 and agreed on November 17th to allow up to two identical (spare) boards to be built, although these spare boards may only be used if the race boards were damaged unintentionally."

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5 hours ago, TimBits said:

to a mono hull sailer looks wrong ....and sure does not help in a pitch pole ... you would think that as these boats are above the water 99% of the time you would not need a wave piercing hull shape and the classic V under would be better to keep the nose when they drop off the foils which seems to happen a lot

When viewed through the prism of a monohull, yes, the inverted wave-piercing hulls do seem very wrong. The difference is though they're on catamarans. A monohull needs a V-shaped hull for stability to dig into the water resulting in the widest point of the hull where it breaks the surface. Just as a tree with a tap root does the same thing. If a monohull had an A-shaped hull, then the widest point would still be where the surface is, but there would be nothing below the surface and nothing overhanging above the surface to provide any resistance to toppling moment. The hull would float right on the surface and topple over very easily. There would also be very little passenger/cargo area to carry stuff in.

A catamaran doesn't need V-shaped hulls for stability. It has that already in spades by virtue of having another hull exactly the same connected to it a fair distance away. Hence a catamaran can benefit from having A-shaped hulls with the widest point and therefore maximum buoyancy where the hulls touch the water surface, thereby preventing it from 'digging in' as much as possible and reducing the 'wet area' frictional losses.

The term wave-piercing, is not really the primary area where the gains come from, but it sounds cool and is the quickest way to explain the concept to novices who ask the question. Monohulls need the traditional flared bow on their V-shaped hulls because they need that ledge as a battering ram forcing the waves out + back down to stop the hull from nose-diving under the waves. It's the only thing that does stop them from nosediving because there is very little displacement and buoyancy down at the pointy, sharp end of the V under the water. For passenger comfort reasons (deflecting wave splash), there is no reason at all why a catamaran with wave-piercing bows couldn't also have the traditional flared bow ledge as a monohull above the water, but as you've already stated, this would have negative aerodynamic consequences reducing speed and increasing fuel consumption for no additional buoyancy benefit. Some large passenger & vehicle catamaran ferries do have just such an X-bow shape if you take a look, for reasons of increasing cargo area as well as for passenger comfort. But the thing is that an A-shaped hull doesn't need the flared gunwhale to provide the resistance against nose-dive because it already has the widest hull X-sectional area of maximum buoyancy right there at the water surface anyway.

Monohulls' V-hulls + flared bows resist nose-dive by pushing against the wave and forcing it back in the opposite direction. This is extremely inefficient as it just burns forward momentum, speed, energy and effort to do so. Water isn't moved in great lumps very easily. Catamarans' wave-piercing A-hulls let the wave continue in the direction it is going and simply cut through it instead, dividing the water so the widest point of the bow at the base with the most displacement and the most buoyancy can keep the bow from submarining by straight forward use of Archimedes principal on the flat water in the trough underneath the whipped-up lumpy wave on top. It wastes far less energy & momentum doing this than it does the V-hull way.

Having said all that, as a passenger, you would much rather be on a V-shaped hull if you like to stay dry. Cutting waves and letting them continue in their direction over the top of your topsides is not what you would call a nice relaxing day out on the water. But these are racing boats and racing boats make compromises for speed, #1 of which is passenger comfort.

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very cool explanation  thanks - OK next question .... why the strange "down at the front" angle of attack of these boats ? the 72's did not have this ... they seemed to foil almost horizontal ... whereas the 50's look as though they are about to become a sub at any moment .... is about getting a better "angle of attack" into the wine for the wing ?  

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35 minutes ago, TimBits said:

very cool explanation  thanks - OK next question .... why the strange "down at the front" angle of attack of these boats ? the 72's did not have this ... they seemed to foil almost horizontal ... whereas the 50's look as though they are about to become a sub at any moment .... is about getting a better "angle of attack" into the wine for the wing ?  

I don't know the answer to this, but like you I'd be interested to know. I think it looks very odd indeed and not at all an attractive stance. I have thought like you and speculated that it might be something to do with the most efficient angle of attack for the wing, but I really don't know. If it is that, then why didn't they just change the angle of the 'mast' or the wing as a whole on the front X-beam and be done with it since they seem to be wanting the same forward stance whether going upwind or 'downwind' (which is of course still actually upwind anyway to the apparent wind when you're travelling at up to 4x the actual wind speed)?

Another question: Why didn't they just make the entire wing out of solar panels and install a 4kW Parker-Hannifin hydraulic pump in one hull and a bank of Li-po batteries in the other hull and then dispose of the 3 crew members who make absolutely no actual sailing contribution whatsoever and lose all the grinders and bicycles? I mean if the competition really wants to be high-tech with flying boats etc. then surely the concept of having human powered pumps to supply a completely hydraulic control system is more than a little ridiculous.

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I am not completely certain of my old and failing memory, but I think I saw something about the nose down stance being needed to avoid wind getting underneath the boat beams/tramp area and lifting it, which would probably mess up stability. Nose down means wind over the boat is tending to press the boat slightly downwards rather than upwards which might cause loss of foil/rudder control.

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1 hour ago, TeamLeader said:

I don't know the answer to this, but like you I'd be interested to know. I think it looks very odd indeed and not at all an attractive stance. I have thought like you and speculated that it might be something to do with the most efficient angle of attack for the wing, but I really don't know. If it is that, then why didn't they just change the angle of the 'mast' or the wing as a whole on the front X-beam and be done with it since they seem to be wanting the same forward stance whether going upwind or 'downwind' (which is of course still actually upwind anyway to the apparent wind when you're travelling at up to 4x the actual wind speed)?

Another question: Why didn't they just make the entire wing out of solar panels and install a 4kW Parker-Hannifin hydraulic pump in one hull and a bank of Li-po batteries in the other hull and then dispose of the 3 crew members who make absolutely no actual sailing contribution whatsoever and lose all the grinders and bicycles? I mean if the competition really wants to be high-tech with flying boats etc. then surely the concept of having human powered pumps to supply a completely hydraulic control system is more than a little ridiculous.

Have you noticed that when they sail 'nose down' the wing leading edge is almost plumb vertical?

 

Edit  Ooops wrong thread, Apologies and many many thanks Rudder NZL

Edited by cosmicsedso
incorrect

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22 minutes ago, kiwispirits said:

I am not completely certain of my old and failing memory, but I think I saw something about the nose down stance being needed to avoid wind getting underneath the boat beams/tramp area and lifting it, which would probably mess up stability. Nose down means wind over the boat is tending to press the boat slightly downwards rather than upwards which might cause loss of foil/rudder control.

I'd believe this if the tramps weren't made of a very open mesh weave that allows water & air to pass straight through with no resistance. Maybe it's something as simple as wanting a tilt forward bias to the tramp so that if the helmsman trips or stumbles while running from one side to the other, they will be less likely to end up in the drink over the rear crossbar?

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Hmmmm all good answers ...  maybe keeping some down force from the cross beams is good but if it was better to sail with them down they could have made them angled down ... might it be that the helmsman and tactician have a much better view ahead ?  especially Team NZ who with the bikes have a much lower profile ... you see that Peter b can sit through most races where as the others all stand or perch .... I will post a quest on Team NZ's FB page and see if we get an answer Looking forward to so more racing tomorrow AM now that my ticker is running at closer to normal speed ...

 

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Ok here is the answer .... sorry it had to come from Oracle 

Video source: Oracle Team USA. -- As I don´t get much from Slingby aussie accent for some words in video above , and Tom also speaking as a 'trade off' to level platform upwind, I went directly with Guru Martin Fischer to get a second thought on the matter.
We covered the bow down attitude here since first pic/video was shown that I remember, also we explained how is possible to achieve a more controlled and faster flight in beachcats with a similar trim.

But AC45T and AC50s are another league so I wanted to confirm again what Groupama Team France lead designer (and flying A-Cat/FP/GC32 pioneer) had to say on how they apply the bow down 'attitude' / trim, he confirms Slingby gral concept but more clear to read/understand:
---------
Martin Fischer: " It's not just a trade off. With the bow down trim you reduce the wetted surface of the rudder. This reduces frictional drag and therefore increases speed.

As of the trade-off Oracle is talking about: we want to sail with maximum elevator differential, which means that the net angle of attack of the elevators with respect to the boat cannot be changed.

Therefore the trim of the boat changes as a function of boat speed (more bow down if the speed goes up). As the result the boats sail downwind with more bow down than upwind. Ideally we would like to have the same bow down trim downwind and upwind, but due to rule constraints we cannot achieve that - if we want to keep the full rudder differential."

https://www.youtube.com/watch?v=fFB3_do8EG0

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15 hours ago, Rudder_NZ said:
16 hours ago, Sportboat Jeff said:

s saying there have been too many google downloads and I can't watch the race #4 (UK/NZ).  WTF???  Why does god hate me so!!!!

Try this or the torrent:
https://www.ampercent.com/bypass-google-drive-download-limit/13333/

That worked really well, thank you!

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yes I think that means oo many people watching it ... download and use VLS 

Rudder any chance of race 3 ?

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Yeah, I got that; but it didn't matter for me.  I am adding the vids to my google drive and then downloading it from my drive, as per Rudder's suggestion.  This has worked no problem for me.

Thanks again Rudder.

 

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Challenger Playoffs day 3

 

Race1 - NZ vs UK (Sorry,For some reason the recording stopped and I didn't notice)
https://drive.google.com/open?id=0BxIm00ZuX5lXa3o4VEpwOHMxVkk

Race2 - Sweden vs Japan
https://drive.google.com/open?id=0BxIm00ZuX5lXTjVxWFlua0R4Znc

Race3 - NZ vs UK
https://drive.google.com/open?id=0BxIm00ZuX5lXLWkyVFNURjVwMVk

Race4 - Sweden vs Japan
https://drive.google.com/open?id=0BxIm00ZuX5lXMS1kbldydkhLcTg

Race5 - NZ vs UK
https://drive.google.com/open?id=0BxIm00ZuX5lXMUVmczZoTUx5WW8

Race6 - Sweden vs Japan
https://drive.google.com/open?id=0BxIm00ZuX5lXTjVxWFlua0R4Znc

Torrent attached.

I am away on holiday for the next 2 days. No promises I can record the races. I will do my best. I will also try get a friend to record them and upload but that might also be hard.

ChallengerPlayoffDay3.torrent

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55 minutes ago, kiwinznz said:

Hi.. Thanks.
Any chance of grabbing a Race1 - NZ vs UK replay?
That certainly left us hanging <grin!>
 

I'm off to work sorry so wont get the chance.

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6 minutes ago, Rudder_NZ said:

Challenger Playoffs day 3

I am away on holiday for the next 2 days. No promises I can record the races. I will do my best. I will also try get a friend to record them and upload but that might also be hard.

Thanks for the mammoth effort, enjoy your holiday :)

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20 hours ago, TimBits said:

very cool explanation  thanks - OK next question .... why the strange "down at the front" angle of attack of these boats ? the 72's did not have this ... they seemed to foil almost horizontal ... whereas the 50's look as though they are about to become a sub at any moment .... is about getting a better "angle of attack" into the wine for the wing ?  

This one has been answered many times but I'll do it again.

The rudders are limited in how far they can rotate about the transverse horizontal axis, can't remember how many degrees, can't be bothered checking the rules, maybe 5 one way and three the other?.  

The leeward rudder stock adjusts around the horizontal transverse axis to adjust the angle of the boat in flight, the foil angle of attack adjusts the flying height (more or less, simplistically put). 

The sailors have discovered that by angling the windward rudder stock forward to its maximum extent they can create significant downforce with the windward rudder, increasing stability and useable power, at the expense of a bit more drag.  Sailing the boat nose down further increases the angle of attack of the windward rudder and hence increases the downforce it generates. 

The AC 72 rule prohibited rotating the rudder on a transverse horizontal axis on the water though IIRC the crews were allowed to adjust it between races or on the dock.

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Thanks again Rudder_NZ!

Race 2 and Race 6 are the same links (Sweden vs Japan - do you mind posting the missing link?

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Yeah, the race 6 link (Sweden v Japan) was deja vu all over again.  Anyone have a reply of the final race today?   Maybe it is in the *.torrent; but I don't know how to view those.? 

 

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All races for the day were in the torrent, except race #1 which failed to record shortly after the race start. Review earlier messages in the this thread for tips on how to download a freeware Torrent application like MicroTorrent etc. Install it, then download the linked torrent file...open it with your freshly installed Torrent app, it will proceed to download all the race files for the day as *.ts format video files and places them in your default downloads folder. The torrent app will also automatically start providing uploads of your newly downloaded files to other global Torrent users looking for the files. You can turn that off if you don't want to share out b/c of internet bandwidth limits on your account or you just like to be called a leech ;-)

 

2 hours ago, ddwjr said:

Yeah, the race 6 link (Sweden v Japan) was deja vu all over again.  Anyone have a reply of the final race today?   Maybe it is in the *.torrent; but I don't know how to view those.? 

 

 

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1 hour ago, jshear said:

Somebody is posting the semifinal races on YouTube.  Complete? races that Rudder_NZ missed are there.  Quality not as good though,

https://www.youtube.com/channel/UCg0qodCqCHAkmu8FkxXixrw

Thank you.  Hopefully You tube doesn't take them down.

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Hi folks,

it's a pitty that link to race 6 is missing. I found a replay for the complete 3rd semi-final day here: http://www.servustv.com/de/Medien/Louis-Vuitton-America-s-Cup6

(linked from here; http://www.servustv.com/de/Sendungen/America-s-Cup-2017 where you can find replay of all days. The ones from the Qualifier even with original world stream commentary)

however I fear that this might be geo blocked (someone please confirm if so).

Worse than that is that the commentary isn't the world stream one, but the one from ServusTV reporters. Fortunately it is in German - so most of the folks outside Germany & Austria will perhaps be spared to understand the crap.

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13 hours ago, Tornado807 said:

All races for the day were in the torrent, except race #1 which failed to record shortly after the race start. Review earlier messages in the this thread for tips on how to download a freeware Torrent application like MicroTorrent etc. Install it, then download the linked torrent file...open it with your freshly installed Torrent app, it will proceed to download all the race files for the day as *.ts format video files and places them in your default downloads folder. The torrent app will also automatically start providing uploads of your newly downloaded files to other global Torrent users looking for the files. You can turn that off if you don't want to share out b/c of internet bandwidth limits on your account or you just like to be called a leech ;-)

 

 

Thanks.  I got it.

Anyone able to fill in while Rudder is on holiday?

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I have the replay of today's race. Unfortunately the upload speed here isn't great. Looks like 2 hours at least. I'll try fix the link for yesterday too.

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Thanks Rudder!!! I had/have access to all the LV & AC racing live on our TV - except for the LV semis. So without your efforts, I wouldn't have seen the semis at all. Can't thank you enough, much appreciated. Cheers...

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