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T Clewring One Design

A-Cats and multihull development

by A-Cat Nationals media on 8 Jan 2012
A-Class Australian Championship 2012 - Wangi Wangi (AUS) - 03/01/12 Glenn Ashby © Andrea Francolini Photography http://www.afrancolini.com/
Emirates Team New Zealand America’s Cup sailor Glenn Ashby is described on the Team website as a multihull specialist.

You could say that.

Since 1996 he has won 14 World championships across three multihull classes, including seven in the A Class. At the 2008 Olympic Games he won a Silver medal, sailing a Tornado with fellow Australian Darren Bundock. He has been sailing and coaching in the Extreme 40 class and was head coach with BMW Oracle’s 90ft trimaran for the 33rd America’s Cup win. Glenn is now the Emirates Team New Zealand 34th AC campaign wing trimmer and a member of the design team.

We talked to Glenn at the 2012 John Cootes Furniture Australian A Class Catamaran Championships, which he won with a race to spare.

‘I spent quite a bit of time sailing dinghies when I was growing up. A bit in the Laser Radial when I was a kid and the Mirror dinghy and the Flying Ant. The Paper Tiger was really the one I started my catamaran sailing in and I did a little bit of Tornado sailing, both steering and crewing, before I actually started sailing A Class. I was about 18 when I got my first A Class and I have been sailing them ever since. They are awesome boats.

‘It is absolutely fantastic that five Oracle Racing America’s Cup guys have come and sailed at the 2012 Australian A Class Catamaran Championships. It’s definitely the strongest A-Cat fleet I have ever sailed against and that includes my seven World Championship events.

‘The A Class is great for really honing your skills for sailing on the bigger multihulls. Everything happens at double speed on the A Class compared to what happens on an bigger boat, so learning the do’s and don’ts and what you can get away with and what you can’t is absolutely applicable to boats like the extreme 40’s, AC45’s and bigger multihulls going forward into the America’s Cup.

‘You roll one of these A-Cats over and you might break a mast and cost yourself a few thousand dollars rather than four or five hundred thousand dollars or more if you roll one of the bigger Cats over.

‘Capsizing - it happens pretty quickly on the A-Cat. When they go they don’t give you much warning and when you are gone you are gone. It’s a little bit similar to skiff sailing or sailing a Moth. When they foil and come out of the water and go down the gurgler you only have a split second to eject.

‘As boats go round the top mark and head for the clearing mark it can get exciting.

‘What happens is the boats are essentially set up to race windward /leeward courses and they are not set up to do reaching, so essentially your foil set up and your rig set up is to maximise your performance upwind and downwind and when you get round onto that clearing reach, which is essentially a 90 degree reach, you are sailing through the power zone, with a multihull.




‘Because you are twisting the sail a lot more than normally you would, both upwind and downwind you lower your centre of effort quite a lot, which loads up your foils a lot more and that means the boat wants to jump out of the water quite a lot more. Not only do you load the foils more but your boat speed is faster as well.

‘The foils start operating over and above what they are designed to do. So you end sailing in a compromised state to get to that clearing mark before you can bear away onto your downwind course.

‘On the practice day in around 22 knots, after rounding the top mark we saw Steve Brewin trying vainly to steer the boat from about two metres astern.

‘We have all gotten into that situation before, so I know exactly how it feels and it is not a fun experience.

‘It’s a transition period where you are going from upwind or you downwind. The main reason the clearing mark is there is so you don’t get right round the top mark and gybe straight back into the oncoming traffic, so it’s a safety aspect of the course. When it is top end windy conditions, the boats are very hard to sail down there accurately and fast.




‘The foil technology has definitely come a long way. Also hull shape technology has come a long way and the foils and the hull shape have essentially worked quite well together. You can have one without the other but having the hull shape to support the right foil is key. The curve foils are there to provide lift and obviously at higher speeds they can provide too much lift at times, if they see too much angle of attack. If you are going off a wave the boat can then jump out of the water.

‘A-Cats are very similar to the Moth in that they jump out of the water, they cavitate and then you come crashing back down.




‘In the A Class most of the boats now have the curved foils. Compared to a few years ago this has been a big step forward and I think in another three or four years the boats that we have now will probably seem quite prehistoric compared to what will be happening down the track.

‘I think that we will definitely roll forward and what we will see over the next two or three years with the America’s Cup technology coming through, will gradually filter down into most multihull classes.

‘Curved foils are nothing new. They have been around for years and years. People tried them back in the 60s and 70s and probably didn’t really know the ins and outs of why they may have shown some promise. I think structurally the materials we have now support a curve foil much better than they would have previously. Foils have come a long way and essentially they just reduce the wetted surface area of the hull going through the water, which means less drag at the high speeds.




‘The ORMA 60 Tri’s have been using curve foils for years and years. There have been many other development speed catamarans that have used curve foils. It’s the technology of how they are used that has come forward a long way. It is like anything - refining something that everyone probably knew worked to actually getting to a stage where you can use it around the tracks.

‘The beauty of the A Class is that all the boats have to conform to a length, width, height, weight box rule.

‘The fact the boards are so cheap and easy to produce and it’s so easy to two boat test new gears or changes, the A Class is really easy to make steps forward. Obviously if there is something faster the Class wants to take on board, everyone will get that improvement and then someone will make a new change and we will all go down that path.

‘The technology rolls along very quickly and you can actually test it very cheaply and easily compared to a lot of the other classes.

‘A Class is really one of the only true development classes, other than the C Class. We have 70 boats on Lake Macquarie for the Australian Championships and for the World Championships we have a limited fleet of 100.

‘There are hundreds and hundreds of A Class catamarans all around the world, all sailing with different guys developing exciting and new things. The wheel spins forward quite fast and many of the larger multihull designs have essentially come from a lot of the developments of the A Class.

'Long may it continue!’

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