More canting keel controversy – We get the views of RORC Rating Office Chief Measurer James Dadd on Volvo 70s and the Cowes Week issue

More canting keel controversy – We get the views of RORC Rating Office Chief Measurer James Dadd on Volvo 70s and the Cowes Week issue

While Open 60s went through a spate of them falling off, canting keels are now causing controversy in other classes. In our recent article looking at the new Ericsson 3 VO70, designer Juan Kouyoumdjian was outspoken on his views on the part of version 2 of the Volvo Open 70 rule governing the canting keel, where the combined weight of bulb and foil is now limited to a maximum of 7.4 tonnes.
Surely, our Argentinian friend queries, combining bulb and foil weight will result in teams putting all the weight in the bulb and reducing the size of foil as much as possible, which cannot be a good thing?

Keen to set the record straight, James Dadd, Chief Measurer at the RORC Rating Office who administer the VO70 rule, gave his view on this.

"When we were writing the second version of the rule, they were saying ‘put in a bulb weight and leave it at that'. But our thought was that if you did that it was going to encourage keel fins with a very low centre of gravity. So if you set the maximum bulb weight to 5.5 tonnes, you'd end up with a fin that is immensely heavy at the bottom and with a huge fin to bulb attachment plate – it would be like a club-footed fin. So we thought that wasn't the best thing to do. What we needed to do was to go for complete keel weight."

According to Dadd they also looked at specifying minimum weights individually for bulb and foil but the result would have been the same. "People would still get the centre of gravity of the fin down lower, so you end up with the club-footed fin again. And that isn't a natural development. It isn't going to give designers and engineers information that they can take into main stream yachting. A the end of the day, the keel fins have always been pushed hard. – I don't think they are being pushed any harder now than they have previously." In short pretty much any rule you specify to try and prevent teams dropping the CoG down will result in foils that look like ‘Frankenstein's monster' as Dadd describes it.

However the keel package is not only limited by weight. There are also minimum sailing load and grounding load requirements and they are specified in the rule in terms of using 390 MPA modulus steel.

"Generally they use higher modulus steels than that," continues Dadd. "But from the Volvo 60s through to the Volvo 70s and the Whitbread 60s before, we found that by putting in grounding loads and sailing loads and the calculations based on 390 MPA steel, as far as the sizing is concerned, you really limit how far people can push the keel fins. So we felt that the most natural way to deal with it was to stick with what we know best and know works and say ‘here's your whole keel weight, you won't get away with a keel fin less than 1750-1800kg' – so that dictates how much you can put into the bulb. At the end of the day we have to think about what is the most productive route for people to be going down."

The new V2 rule prohibits the ‘bomb door' sliding panel covering the keel pin aperture in the underside of the hull, instead clearly permitting a hollow in the hull to accept the keel pin, the set-up seen on the ABN AMRO boats in the last race.

V2 also limits the permissible material of the hydraulic rams used to cant the keel, to steel only (ie no carbon or titanium). While all the teams are using either Cariboni or Greg Waters for their hydraulics, Dadd says that following the new limitation some teams have been investigating getting rams made from very high strength steels. "They are trying to get to the same sort of properties as titanium, so they are using these military grade steels that the engineers have never worked with before and the steel is just as expensive as titanium. It is one of those things – you are damned if you do, damned if you don't."

Given that all the boats are at maximum beam, maximum sail area and maximum weight for the keel package, presumably the boats will have similar righting moment, so one wonders why not avoid this ridiculous cost, not to mention the potential for dubious reliability and simply specify the rams all the teams can use.

Dadd says he thinks it was a mistake to ban titanium rams. His concern was carbon ones, which movistar trialled in the last race. "I was down in Sansenxo the day they installed them and I think it was half an hour before they came in!"

Obviously at present the Rating Office is gearing up to do the rounds of the new generation Volvo boats. The Confidential Interpretations are to be made public this Saturday, but Dadd says there is nothing radical in them and not surprisingly, this being the second time around with the rule, there are less of them.

This may also be due to the V2 box getting tighter? "What I think is going to be interesting is the sails, which we've tried to open up quite a lot, but we are not going to see much of that until we get nearer to the start of the race. As far as the boat design is concerned, everyone is aiming for maximum keel weight and maximum beam and everyone is heading in a similar direction. I think everyone has a starting point from last time being ABN AMRO One, whereas last time no one knew where to start. Juan K and Mike Sanderson started more with the Open 60 attitude whereas a lot of the others started from the Volvo 60s which ended up not being the right place to start. This time they have realised that with these boats you want the righting moment, you want that extra form stability, so you go out wide."

Skandia Cowes Week and canting keelers

This debate has come to the fore mainly due to ABN AMRO One's demolition of Class Zero at Skandia Cowes Week in 2006.

Dadd has his views on this: "To be honest the reason ABN romped around was that it was a really breezy start to Cowes Week and they were ideal conditions for the boat. It had just finished the Volvo race, so it was fully worked up and optimised and it had the full race crew on board. If those guys hadn't won their class in those conditions, something would have been wrong. And later on in the week when the breeze died they were down the pan and couldn't keep up. That is a limitation of the single point rating system: every dog has its day."

It could be argued that had ABN AMRO One been a fixed keel boat fresh from a Volvo Ocean Race win, her fully professional, world class crew with 30,000 miles on the clock, then she still would have dominated Class Zero at Cowes Week. Perhaps the argument is less over canting keelers, as full-on grand prix race boats, sailed by top international pro sailors, daring to turn up at what is essentially an amateur regatta and giving the local competition a sound kicking?

Dadd reckons IRC is getting better at equalising canting keelers, but says he sympathises with the position of Stuart Quarrie and the Cowes Week committee: "If you look down in Australia where there are the most canting keel boats racing within the general fleet – they are not winning every race or regatta. I think in general racing terms, we are dealing with the canting keels fairly well in IRC at the moment, but I do understand Stuart's concerns. With the style of racing that you have during Cowes Week, with lots of reaching and fetching, I can see their reasoning that canting keel boats might have an advantage because those are the conditions they do well. But it is difficult because you it is still new technology so you are only seeing canting keels on boats that are well campaigned. If you look at the crew lists on the boats and who is running the boats and how much time and effort is put into them, whether they are canting keel or fixed keels they should be up there winning, because they are such well run campaigns."

Dadd reckons that if their numbers are small, rather than requiring boats to fix their keels on the centreline, which they are not designed to do, they
should be prohibited from competing instead… "which would be a shame, particularly when they have decided to make an exhibition event of the Open 60s going around the island. It is like composite standing rigging – canting keels are here, it is going to appear and I think we have to accept it. If you look at the polar diagrams from a Cookson 50 [canting keeler], a TP52 and an IOR 50 you'll find that the Cookson 50 and the TP52 polars look more similar than the TP 52 and the IOR 50. But no one complains about an IOR 50 and a TP 52 taking part in the same regatta…"

Dadd also adds that effectively prohibiting the canting keelers will detract from the media side of the events. "It is great for ABN AMRO to have had their boat there and take people out. And it is also great for your average sailor to be sailing along and all of a sudden they have ABN AMRO coming up behind them and overtaking them. That is one of the great things about Cowes Week – to see the really sexy toys out there and the rock stars out playing on them. I think it is a shame to discourage them."

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