Cutting edge

BMW Oracle Racing's Ian Burns discusses jumper less rigs and the latest innovations in Cup design

Thursday May 18th 2006, Author: James Boyd, Location: none selected
This article follows on from yesterday's feature

While there may be much theorising about what is taking place beneath the waterline on USA-87 a more obvious area of development being worked on is jumperless rigs. Jumpers, the diamond of rigging that braces the top mast, are a standard feature of Cup rigs but of course this being the America's Cup they have reached new levels of sophistication and most have ability to allow the jumper on each side of the mast to be pumped forwards by a small hydraulic ram. The reason for this is that when sailing upwind the leeward jumper can be 'relaxed' aft allowing for a tighter sheeting angle without impeding the roach of the headsail. This is not new technology - hydraulic jumpers have been used in the Cup since the days of the 12 metres.

Obviously hydraulic jumpers equals not only weight aloft but windage too, so Alinghi have been very evident in their experiments with simply removing the jumpers from the rig currently on SUI-64, hydraulics and all. Obviously in doing so they have had to increase the structure within the top mast with the end result that the weight saving may have been minimal. Of course as soon as Alinghi tried this, there was much curtain fluttering from the other Cup teams and within the space of around two weeks BMW Oracle Racing emerged with their own version.

"The gains are small, but measurable in windage to get rid of those rods," comments Ian Burns of this new development. "There is quite a lot of paraphernalia that is involved with having jumpers that you can adjust fore and aft with hydraulics and so there are obvious gains in getting rid of it. But on the downside you have to make the mast larger in section and there are all sorts of stiffness and strength requirements to get rid of that rigging, so it is a bit of a trade off and it is hard to get an answer exactly because the trade-offs are quite complex. So one of the ways to check it out is to try it."

Obviously neither team have been that impressed with the results as neither used the rig in Act 10, leaving many conspiracy theorists to wonder if this hadn't been an Alinghi techno-red herring.

This is one of the key games in the America's Cup - knowing where to spend your resource and this becomes a particularly hard call for smaller, less well funded teams. "You see a jumpless rig down at Alinghi and you think, it would be great to see one of those, but if you only have two rigs - your race rig and your spare - what do you do? Do you build two jumper-less rigs and turn up with something that might not be any good and Alinghi may not use anyway or do you do one of each and have a good one and a bad one. This is the real challenge that faces people as time and money runs out - your options become less and less."

For the 2007 America's Cup there is a new version of the America's Cup rule shaving off a tonne of displacement and increasing the spinnaker pole length and thus downwind sail area. Otherwise the design box has narrowed with the latest Version 5 of the rule. Burns doesn't think this has made much change to the design process. "I don’t think the narrowing of the rule has really impacted where the gains available are and the differences between the teams. If you look at the last Cup although the number of boats started in different places they all migrated to the same sail area, same length and same displacement."

With Version 5 of the rule, the box was effectively shrunk around the area where Cup teams ended up in 2003. Saying this there much still much variation possible. While Burns reckons there is now only around 50mm of tolerance when it comes to the 20m overall length of Cup boats, and 150 kg within a 24 tonnes maximum displacement, when it comes to waterline beam it is more like 5-10%.

"There are probably half a dozen parameters in the design of the boat from how the bow is treated, the stern is treated, the volume distribution, the sectional shape of the boat - you can see some relatively extreme shapes in a couple of the boats out there," continues Burns. "These all go hand in hand. The real game is to understand each one individually and then also combine them and do the research on the combined things and make sure 1+1 does equal 2. That is one of the hardest thing to step into from your initial studies into what each part of the boat is worth and how it is treated and combining them into a package that gets gains even more so."

When it comes to the process of creating an America's Cup boats Burns believes the most significant development since the last Cup has been in the trust they now place in their CFD tools. "We can now do pretty accurate complex models of the yacht hulls and do it in a production sense - ie we can turn them around fairly quickly which means you can do a lot of experiments. It still takes a long time. You can get big computers and you can run them full speed 24 hours a day but it still takes a number of days, sometimes even weeks to get a solution. But that is similar to a tank test and it is much less expensive once it is all established, per run and much quicker - from the design to an answer it might be two weeks, whereas a tank test session could be months once you have made the models and got time in the tank.



"So I think that now the differences are smaller, the CFD has started to work its way in as a more production-orientated design tool. Even last Cup doing a number of cycles with a complex, dense-gridded CFD tool was really quite a challenge, a big resource hole and the reliability and the confidence in the results really wasn’t there. Now we can turn over things much more quickly, you can do a lot more validation and develop confidence in the tools and then use them for design."

With the freeing up of national restrictions in the America's Cup so teams are able to look outside of the country from which they are challenging and as a result this cycle BMW Oracle Racing have joined Alinghi and Mascalzone Latino-Capitalia Team in using the giant tank test facility in Newfoundland. However while tank testing is still a primary means of gaining data on hulls and appendages Burns feels that at a time when their demand for accuracy has gone up, there is not much more tank testing can deliver in this respect.

Since their last campaign the BMW Oracle Racing design team has also been restructured. While for 2003 the principle R&D work was carried out by the Farr office there is now more of a team approach. At present the design team includes around 30 people from 10 countries, with more full time staff. This list includes Bruce Farr, Juan Kouyoumdjian, 14 designer Paul Bieker, sails designers JB Braun, Steve Calder and Mickey Ickert, Southern Spars rig specialist Steve Wilson along with a host of backroom scientists and specialists. Talented Frenchman Mick Kermerac is working for them on appendages.



"The stronger teams are not the strongest because they spend money - they hire some very clever design teams," says Burns. "You put those guys together and if you get them working well together you end up with a very nice package.

The association with German car manufacturer BMW is not simply one of sponsorship but also swapping technical know-how and is providing valuable input to their campaign. "They have come up with some great, innovative solutions which we might never have even got to because they came from a completely different view point. And generally they have some pretty good insight into things we’ve never known about. Conversely the composite side isn’t their strength - those guys design most things in steel and aluminium so we’ve been able to bolster that up with our own resources and with some new people we’ve got on board. In that area we have come a long way from our last effort and I’d be surprised if many teams had the resources and strength in that area courtesy of BMW and our work together we have got."

Managing such a large team particularly including both Farr and Juan K one would imagine could be a challenge, but Burns says they are working surprising well together. "They have proven what professionals they are, they have really worked surprisingly well together," he says of the two designers currently at loggerheads in the Volvo Ocean Race. "They come from different viewpoints, but both respect each other’s viewpoints and I’m sure both have learned a lot from working together. To date we haven’t had an issue, but the fact is that both those guys if they see something good they are happy to put it into their boats and they draw boats as fast as I can get them to draw boats."

Burns also feels that while for example Alinghi's sailing team effectively took a year off after the last Cup, they were spending this time testing on the water. "We have done a lot of on the water sailing testing. We started in December 03 and I think there have been too many times when teams have been sailing when we haven’t."

So what does Burns think about the new efforts from Luna Rossa and Emirates Team New Zealand? "The Team New Zealand boat looks like a really good job at a low drag package. They have a very efficient-looking hull, very efficient-looking sails - if they get it all together it will be a very good boat. Luna Rossa is a little more in the main stream, nothing so out to one side, but historically that is a pretty good way to win the America’s Cup. I think they have done a pretty nice job too."

As to a new boat for the America's Cup post-2007, Burns seems to be in two minds over whether the Cup boat should be something completely new and state of the art with canting keels and wing rigs or substantially larger, or sticking with a new iteration of the present ACC boat.

"We agonised over it last time when Alinghi was formulating the rule. The good thing was that we had pretty clear direction on the key ingredients that were desired from Ernesto [Bertarelli] and it happened to coincide with what Larry [Ellison] envisaged for the Cup boats as well. So we had a good working direction to go with which made the job easier. Personally I think these boats are pretty good for what they do. There is the question over whether the technology is the latest or not. But we have a fairly good turn out of boats here. We have boats that old but still competitive with some modification against boats that are new. It is unlikely we are going to have anyone out there who is not competitive on their day if they do everything right- if they get some good sails and rigs on the boats. So I think the rule is a pretty good shot for this time."

A lot of choice over a new Cup boat will come down to who wins it and where the next event will be held and in what time frame. If for example Alinghi win again and reduce the cycle to three years then this would be too short a period of time to introduce a new boat feels Burns. "I think it is fairly well proven this time around that changing everything dramatically has to be done very carefully." The argument also comes down to - if you dramatically change the boat to something state of the art, particularly a large boat as has been mooted, then you will certainly get less challengers.

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