Talk:AC72

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WikiProject Sailing (Rated Start-class, Mid-importance)
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Question[edit]

Something is clearly confused here. If the boat can sail at all reasonably close to the wind (and obviously it can), the apparent wind speed would have to be well in excess of 17 knots if the boat was making 40 knots.

No, foiling boats regularly exceed the wind speed up wind. The AC72 New Zealand was out pacing a 25ft deep V chase boat with 4 300hp motors. Dont ask me how! Its just physics. The data came from Peter Lester an Olympic class yachtsman with many years experience on all kinds of Americas cup boats.
I don't doubt that they regularly exceed the wind speed. But there is a world of difference between that and exceeding the _apparent_ wind speed - especially exceeding it by a factor of two when sailing close to the wind. That's not just impossible; it's absurd. I suspect one of two things; the wind speed was 17 knots and the word "apparent" is spurious - or the apparent wind speed was 70 knots. Pinkbeast (talk) 00:48, 20 October 2012 (UTC)

It seems the media may not have appreciated the difference between the 2 terms . On the day, looking at the weather forecast, it seems 17 knots was the wind speed. I dont think even the kiwis would be sailing in 70 knots! The media were probably confused because wind speed in normal weather forecasts in NZ is metric ie Km per hour and knots are only used by shippy folk. — Preceding unsigned comment added by 122.62.226.243 (talk) 02:02, 21 October 2012 (UTC)

Fast than apparent wind: draw a vector triangle with a boat speed of 20kn, a true wind of 12kn from 127 degree (broad reach) and an apparent wind of 16kn from 37 degree (slightly bream reach). That's it. An AC72 should be faster in this true wind from this true direction. The BOR90 made in about 8kn true wind on the first broad reaching leg of the second race in the last AC off Valencia over 30kn.--46.115.68.209 (talk) 18:28, 10 August 2013 (UTC)

This is explained in sailing faster than the wind.--Gautier lebon (talk) 13:45, 15 September 2013 (UTC)

weight[edit]

There have been some hints that the NZ cat foils so well as it is extremely light due to some new technology they have invented to do with modifications to the carbon and resin and the system they use to combine the two. Auckland University School of engineering works closely with Team Nz in testing new products. One of the giveaways is the ease with which the Nz boat gets up on its foils and stays there . — Preceding unsigned comment added by 122.62.226.243 (talk) 02:10, 21 October 2012 (UTC)

You have already suggested this, heavily added to the article, with redundancies and falsehoods, whilst providing unsufficient sourcing. You are welcome to contribute, but please use an encyclopedia style and give relevant URL sources for proof. Please cite *what* Auckland University had done for this campaign. signed:Donan Raven (talk) 21:11, 25 November 2012 (UTC)

Use of electronic sensors[edit]

It has been suggested by knowledgeable designers that one of the reasons that the New Zealand is so superior is that it is very stable on its foils when sailing. Helmsmen of high speed foiling cats have commented in the past that it is virtually impossible for a human helmsman to co-ordinate all the parameters that keep a foil boat stable. Martin Fischer identified that the most difficult is the "Z factor"-the rising and sinking of the hull on its foils. Experiments in smaller foiling cats have shown that it is quite possible to control the Z factor by the use of embedded electronic sensors attached to an on board computer. The computer is programmed to take over some of the decision making from the helmsman leaving him to concentrate on the more conventional steering. Team NZ has considerable past experience with the use of embedded sensors in hulls and spars to get real world feed back on the comparative virtues of different shapes. The team has not released any information about the use sensors to part control "flight". — Preceding unsigned comment added by 122.62.226.243 (talk) 21:41, 12 December 2012 (UTC)

Of course they haven't released any information about this. It is prohibited by the rules and they aren't doing it.--Paul (talk) 19:17, 15 March 2013 (UTC)

In the latter stages of the last Americas cup Team Oracle used a wing flap servo from a Boeing 747 controlled by a computer to control the "Z factor"-before this the boat never won a race, afterwards it never lost a race.The servo was included in a system fitted by a group of New Zealand boat builders who were flown up to San Diego by Larry Ellison. They worked 40 hours straight to fit the system.

Article misses Intended Purpose?[edit]

This article seems to have strayed from its intent - a description of the AC72 class of sailboat developed for the America's Cup competition.

Please look to the articles for earlier America's Cup technical classes (International America's Cup Class, 12-metre class, J-class yacht). These articles focus on providing tech info and history for previous classes.

While this article's present (March 15 2013) discussion of testing dates and team activity and rebuilding plans and blow-by-blow of USA Team Oracle's October 17 San Francisco mishap are interesting, these apply more to the specifics of the overall preparation for the 2013 America's Cup, and less to the tech info and history of the AC72 class.

Appreciate that the story of the AC72 class is still being written in real time - but a real time article of every new event does not serve the article. I'm confident that many of you sailing enthusiasts will have great insight and knowledge on the AC72 class, and trust that your expertise can bring this article into focus.

Jmg38 (talk) 03:42, 16 March 2013 (UTC)

User_talk:122.62.226.243 appends uninteresting, misleading, unsourced & unencyclopedic content far too often. It should be trimmed significantly and serve the purpose of describing the class in general, not serve as some anonymous punk's own research and blogroll.. signed:Donan Raven (talk) 18:19, 17 March 2013 (UTC)
I've gutted the article in line with this dicussion - have I gone to far? I tried to provide a framework for the article to be expanded. Happy to discuss, I just decided to do the bold part of WP:BRD. Mattlore (talk) 22:22, 19 March 2013 (UTC)
Way to go, Mattlore! This is a GREAT improvement. --Paul (talk) 23:59, 19 March 2013 (UTC)

You may as well have removed the whole article. The AC72 information was referenced/sourced from the mainstream media which in New Zealand at least is very interested in the AC72 development and is generally well informed about maritime matters. I would hazard a guess that it was the most accessible information available to the public at large world wide. As pointed out, this vessel's development is happening now- in real time. The edits reflect that. Team NZ has allowed close media inspection of their boat including taking media for rides. They have been more than helpful to the Italians. You have removed all of the information about various technical improvements and developments from a variety of sources. Your mind set is revealed by the term "anonymous punk". Anyone who has followed team NZ since the 90s knows they have close links to the University of Auckland.Even the American opposition has kiwis in key areas. This craft is different to the old Americas cup boats which were just rehashing old well tried technology. — Preceding unsigned comment added by 122.62.226.243 (talk) 22:15, 24 March 2013 (UTC)

My statement was raw I admit, but encyclopedia guidelines require accessible sources, and those developments with the University of Auckland are anybody's guess. The encyclopedia has to be succinct and extremely precise (beyond doubt, and while you may have contributed, please take this article trimming by Mattlore kindly, and please keep contributing - within said guidelines. You can start by quoting Mssrs. Melvin & Morelli, the authors of the class. Yours. . signed:Donan Raven (talk) 22:37, 24 March 2013 (UTC)
A lot of the information I removed was not relevent to the AC72. Instead it should be included on an article about the specific team or in the 2013 America's Cup or 2013 Louis Vuitton Cup pages. This article is about the class of yacht and needs to be kept on topic. Mattlore (talk) 23:07, 24 March 2013 (UTC)

Wrong hull weight[edit]

Caused by using the template "Infobox Sailboat Specifications" the weight is given incorrectly. The hull weight is not specified by the class rules, but the total "sailing weight" (AC72-rule 5.10 says: "The sailing weight shall be between 5720 kg and 5920 kg") under measurement conditions (AC72-rule 5.11: with wingmast, sails, security and ACRM equipment, without crew). Unfortunately the template suplies no item like "sailing weight", "total weight", "displacement" or "measurement weight". Due to the high weight of the obligatory media equipment (180kg) and the wingmast+sails (ca. 1500kg) we are talking about an error of about 30%. This should be corrected somehow, but the template does not cooperate...--46.115.68.209 (talk) 17:57, 10 August 2013 (UTC)

2. The length limitation of 22.000m doesn't concern the LWL but the length of the floaters/hulls, actually the length between "stern plane" and "stem plane" (Rule 5.3). On the VOR70s or Open60s and other modern racers this often corresponds to the LWL but not on the AC72s (look thoroughly the drawings and photographs). So this item also doesn't work with the template "Infobox Sailboat Specifications". It looks like that this template is not the best choice to display the specifications of a (very) modern catamaran.--46.115.38.19 (talk) 01:32, 9 September 2013 (UTC)

IRC calls this LH (length of hull).. signed:Donan Raven (talk) 22:54, 9 September 2013 (UTC)


invented?[edit]

When was the idea of having hydrofoils on a catamaran first thought up? Just curious. — Preceding unsigned comment added by Two Wrongs (talkcontribs) 20:11, 13 June 2015 (UTC)

Enrico Forlanini began working on hydrofoils in 1898. signed:Donan Raven (talk) 20:49, 14 June 2015 (UTC)

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