Sail-World.com : Gladwell's Line: Alinghi let their Cat out of the bag
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Gladwell's Line: Alinghi let their Cat out of the bag |
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'The Alinghi catamaran - starboard hull is against the far wall, in the foreground is the prodder which runs the length of the 90ft LWL boat, with an overall length of 120ft and beam of 90ft. the massive crossbeam can also be seen'
Vicarage Photography
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Alinghi hosted a group of media over their America's Cup defender, overnight (NZT). Sail-World was not one of those invited, again, and we are reliant on images and information from others. However we will gladly report any information that comes to hand provided we believe it to be reliable.
One of the conditions of the invitation is believed to be an embargo on reporting any detail of the new yacht, and stories from those present will be released tomorrow. We believe those stories have to be cleared by Alinghi to avoid leaking any details of the new yacht. Quite why they bother is a little beyond us, as the boat will be revealed to all, including spy cameras in a few days and with no espionage rules in place, pretty well anything goes.
One of the Golden Rules of media and PR, and particularly with the America's Cup, is to treat everyone as evenhandedly as possible. For some time now, Alinghi have failed to grasp this fundamental, and, like others of that same failing, are handed some very poor press as a result.
(PS: Around 24 hours after the unveiling, the release and photos of the 'Alinghi 5', arrived, and are posted along with official release. Several of the images supplied were not from the unveiling, but during the building process two or three weeks previous we would guess.)
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While it is not possible to invite everyone to such a function, it is possible to provide images, audio, video and a media release, as a starting point for stories and coverage, Again this basic was not done.
However leaving that train wreck behind, Stuart Alexander of the UK daily newspaper, The Independent, was one of those invited and provided a report, the salient points of which are as follows:
The twin hulls of the catamaran are nearly 90-foot apart when measured from outside edge to outside edge. But it has a huge, central carbon fibre impaler projecting forward which increases its sail carrying length to over 120 feet. There will be various masts, both a hard wing and soft sail versions, with leapfrog tests to decide which is the best way forward.
It will be so tall, perhaps 180 feet, with the area of a jumbo jet wing stood vertically. In addition there will be headsails which could be 1,000 square metres in area.
The crew of between 20 and 25 will have to dance from side to side as the boat zigzags up and down the course on a trampoline stretched between the hulls and the central structure with an area of about two tennis courts. When the wind heels the boat over, they will have to sit about four storeys high on edge of the flying hull. If it ever reached eight storeys then big trouble could be imminent.
Falling that far into a mass of deck hardware could lead to serious injury. Health and life insurance for the crews is a real problem, crash helmets, all fitted with intercom systems, are de rigeur. And the pressure exerted on a ball joint about the size of four crown green bowls will be well in excess of 100 tonnes.
Under that pivotal point is a cat's cradle of support and tension rigging. If one fails then the whole system could implode. No wonder that both teams have had to step gingerly when finding out just what these monsters of capable of delivering. And the Oracle boys are letting everyone believe that they have a newer boat, also a twin-hulled catamaran rather than their original three-hulled trimaran, nearly ready to launch.
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To read the full text of Stuart Alexander's story click here
What can we see from the solitary image and the facts contained in Stuart Alexander's fine prose?
First, the vessel is clearly a catamaran, with bows of a type which are state of the art in high performance inshore racing catamarans, notably Int A-class cats.
 | Underbelly of Le Black shows the dolphin strikers used for maintenance of hull rig tension - George Johns-Alinghi |
Secondly Alinghi is stated to be 90ft long with a 90ft beam, and she appears to be more of a development of the inshore catamaran type than say the D35 type popular in Switzerland for lake racing.
Present is a massive curved centre load bearing beam, which will take the loads from the single mast, which will rotate on this beam on a large ball joint.
Also present is the massive prodder, which may well extend the overall length to 120ft. Quite what will be set on this is not known - the determining factor being the amount of upward luff tension that the prodder can support. It remains to be seen whether the prodder is sufficient to take the massive Code Zero's so popular in the lake cats. The determining factor here will be the depth of the dolphin striker, and gauging from practice aboard Le Black we can guess that any foresail carried will come midway off this prodder with the full length being used for downwind sails, commonly known as a 'Screecher' .
Although not visible in initial photo, we would expect the Prodder to run the length of the yacht and for the cross beams and then hulls to be hung off this focal point (confirmed in later images received). We would then expect to see a trampoline run from either side of the prodder to the hulls - giving crews a 25 metre plus 'Moonwalk' between tacks.
Our pick is that Alinghi will try and get some form of a hard wing sail running on this platform, and will use the soft sail option if there are insurmountable technical issues with a wingsail of this size, or if wind conditions dictate. An option with the hard wingsail is to have a smaller version for strong winds.
If the wingsail is used then the jib may be quite small - its primary use being for tacking.
On Stars and Stripes, used in the 1987 Big Boat vs The Cat 'Match, both wing sail and soft sail options were developed, and eventually only the soft sail option was used.
Due to the fact that a wingsail is only sheeted laterally the winch loads are much reduced, and presumably crew numbers. On the image of 41ft Le Black pictured, there are six crew, yet Alexander talks of 20-25 crew for a yacht that is only 2.2 times the length. The larger figure is presumably for the soft sail rig, which will require more grinding and winch power.
Probably the telling comment on the options comes from Alinghi and renowned inshore multihull designer, Duncan MacLane (USA) who commented in the August issue of Seahorse on the issues of weight, displacement, drag and other options 'Build the boat as light as possible, subject to structural demands, and get the proper stability by matching beam to the sail plan.'
Elsewhere in the Seahorse article, MacLane explains:
'Matching lateral stability (maximum sail force) with fore and aft stabilityto handle the sail force without pitchpoling is a fine tradeoff, and needs to be carefully coupled to mast height and sail plan. Again, proper choice is tied closely to expected wind velocity.
'With Star & Stripes in 1988 we went for long hulls with relatively low ratio of beam to waterline length (30/55 = 0.55). The goal was to promote early hull flying in the predominantly light winds we were expecting. We developed a very large sail plan for downwind sailing (again promoting constant hull flying) and, to provide extra margin against pitch poling, we raked the bows to provide an increased waterline length when the boat was pressed. Rig height and sail area choices were optimised for the light-air San Diego venue.
 | Duncan MacLane at the helm of Cogito (USA) winner of the 1996 Little America’s Cup. Generating power to fly a hull in light winds, and reduce drag is essential - including having the crew weight to leeward. - Richard Gladwell |
The boats were highly refined for the venue, but were lacking in stability in winds over about 8kt. For stronger wind strengths an increased maximum beam would have yielded improved upwind performance.
'The trick, as with all boat design, is in getting the trade-offs right. Benefits to be had by modifying one parameter often have an adverse effect elsewhere. With the basic boat parameters established for a particular performance window, the sail plan and mast height need to be fine-tuned for the expected conditions. With the multihulls’ extreme efficiencies, where subtle changes can lead to performance differences measured in knots (not tenths), getting the sizing of the sail plan wrong can leave you hopelessly slow in light air, or out of control and prone to capsize in heavy weather.'
What lies ahead of the new Alinghi is a period of careful testing to see how the on the water results match the story told by the design computer.
No-one has really pushed the catamaran envelop as far as Alinghi would seem to have done an inshore racer. Initially it would seem that the lighter approach is the better approach - which means that the weight of the hard wing sail will be tested against the soft sail options, including the number of crew and their weight required for the rig options, and then looking at sails that can be flown with either rig.
All while trying to push the limits without a catastrophic failure or capsize.
With the platform unveiled yesterday, Alinghi look to have some good options, and certainly with someone of Duncan MacLane's experience they have a designer who should be able to get the formula right and trade-offs optimised.
Alinghi's progress will be watched with great interest. And their PR can only improve.
 | The Mi26 helicopter or 'Skyhook' which is believed to be used to hoist Alinghi to Lake Geneva - |
by Richard Gladwell
7:54 AM Sat 4 Jul 2009 GMT
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