Downwind trapezing on the A Class Cat - The Drum
by Sail-World.com on 11 Jan 2012
After watching seven times A Class Catamaran World Champion Glenn Ashby so often sail away from the 2012 A–Cat Australian Championship fleet downwind, many sailors are uncertain if Ashby’s downwind technique is something they need to add to their inventory or if it’s a psychological trick being played on them.
Ashby traps to the clearing mark then down the course when the breeze is up Sail-World now on Facebook https://www.facebook.com/pages/Sail-World/102413713136283
The way 49er World Champion Nathan Outteridge, a relative 'newbie' in the class, yes he was 11th at the 2009 Worlds, but having had just had a few days with this new downwind technique and then came second at the Australian titles ahead of the top five from the 2011 World Championship, should put paid to the trick theory.
Glenn, as always, was happy to share his experience and post-event he talked to Sail-World.com
‘Downwind trapezing... what it does is give you another mode of sailing and if you are sitting inboard, you have a certain mode, when you hike you can sail a little bit higher but when you get all your body weight out on the edge of the boat you can sail in that next mode. It’s basically another gear of being able to sail faster.
‘It’s getting out (on the trapeze) and making the boat go forward, just going faster through the water.
‘With the older boats with the straight boards you get out on the water and load the rig up and they go faster but they go a little bit higher.
‘The new boats don’t seem to pay a huge penalty if you trapeze. With the curve boards the faster you go the more they lift so the more the boat unweights. You are sailing faster but because the boat has got slightly less wetted surface area your apparent (wind angle) goes forward and you end up sailing in roughly the same depth as what you do when you are sitting in, or very close to it anyway.
‘In last week’s 2012 A-Cat Nationals, overall I think I would have been very solid downwind just sitting in anyway and I don’t think the result would have really changed, if I had been.
‘I have always been fast downwind, whether it’s the older boats or the newer boats, but I have always struggled to hang in there upwind.
‘Downwind trapezing is most valuable on those days with significant bands/spots of pressure. They are the days where it absolutely makes a huge difference.
‘What you can do, is you can sit in and soak low in a certain angle or pressure or if you want to get out on the wire it will often allow you to rip across the front on the face of a gust to get into another one, or even just go forwards into a gust so you actually stay in it.
‘If a gust is blowing down the course quickly, if you can get into the back end of it you can almost sail into the back of the pressure. It’s like just sailing a boat faster. If you can stay in extra pressure then the better you depth will be.
‘It is less valuable in an overall gradient pressure breeze.
‘It is more of a mode change. I think on the windy days it’s still quicker and I think it is a little quicker when it is in between 11-20 knots. I believe it is probably quicker to stretch out at times but it also depends on your body weight too.
‘If you are in the 90 kilo range, that’s the bigger taller guys, for them hiking off the back of the boat is probably the same as (shorter) me riding out on the trapeze.
‘On days where there are bullets all over the place, when it is gusty and shifty, the fact that you are riding and you are further out on the boat and when the boat loads up initially you go forwards in the pressure.
‘The boat is accelerating forwards. If you are sitting inboard the hull is flying and you are actually pulling in a sheet quite aggressively because of the apparent wind swing round behind you.
‘The boat is accelerating but I don’t think it accelerates quite as aggressively as when you are standing out on the hull.
‘When you are standing on your feet, a bit like the 49ers, you can actually move your body weight fore and aft and inboard and outboard quite accurately whilst still trimming and steering well, so on those shifty, puffy days you can really manipulate the fore and aft trim of the boat and also your inboard and outboard weight.
‘That actually makes quite a big difference, whereas when you are sitting down you have got to bum shuffle yourself around the boat to keep fore and aft trim.
‘You generally sail the hull a click higher downwind (than upwind) because you need a little more of a steering groove with the pressure lulls and puffs and the way you are steering the boat.
‘What you are trying to avoid is the wing hull touching down because as soon as it touches down the drag goes through the roof.
‘You can steer much more accurately with the hull very close to the water. But you want to be able to steer a slightly bigger groove downwind, without touching down.
‘You will actually want to be flying the hull a little higher as you are coming into the lull, sailing a little more heel because that unloads the rig a little bit.
‘As you sail into the lull, the hull would normally start coming down but you can already be steering up to keep it flying.
'Whereas if you are sailing into a really big band of pressure, you can start flattening the boat off and almost touching the hull down just as you are sailing into the pressure.
‘When the boat actually loads up you are at the maximum righting moment, essentially where the rig goes into the pressure and the boat will actually accelerate as the pressure comes on and the hull can then fly a little bit but you have already had the boat flat so you can make use of all the power before you have to start easing the sheet or bearing away.
‘Another downwind trapezing advantage is better visibility. I think that’s probably one of the biggest things with standing on the back, you can see so much more if you just sit up in your trapeze harness - you can really look around.
‘In the days when I was sailing as crew with Darren (Bundock) on the Tornado or on the F18, I would have much more vision than the helm when I was on the trapeze. You are just that half metre higher and it’s amazing what you can see.
‘Often when you are sailing along and just a little bit unsure of the best direction to go, you will fly the hull a half a metre higher for 20 or 30 metres while you have a good look around and it’s amazing what the elevation can do to see what pressure is coming down the course.
‘Its super helpful not just for the downwind but it is helpful for making a decision for which way to go for the next work.
‘Quite routinely two thirds of the way down the run, you can have a good look around to see which way upwind is going to be better and that’s definitely improved by being out on the wire.
‘The extra mode means you probably have an eight degree window sailing downwind whereas on a spinnaker boat, for example, you might have a one or two degree window of where you can point (the boat) downwind.
‘Tactically it gives you quite a big range to deal with, which is great.’