fill your mind
As the world waits for our video exposé on the Little AC defender’s new ride “Fill Your Hands”, her crew and wing trimmer checks in with a definitive answer to the foiling question. Note too that the C-Class finally has their website rolling along; it’s all coming together for the world’s coolest sailing event…now let’s hear from Magnus:
So basically if you ain’t foiling you’re screwed is what everyone’s saying? Well that was basically what happened at the big AC and it seems to be the case here. It could be that the foiling boats suffer greatly upwind with the rest of the junk they have to carry around, perhaps not. Either way, once you turn the corner, the benefits of foiling to some extent or another are rather obvious.
Even last year with FYH we were doing foil assist and the difference was massive in simply how much easier it was to sail the boat. That and it didn’t slow down in wave troughs, etc. There is a photo of us just cruising along earlier in this thread, Fred and I are just sitting to windward with a relatively high degree of righting moment, sailing decent angles downhill. Canaan in the same conditions, about 13 kn TWS was having a wee bit of trouble for the boys. They had not sailed it in that condition before and she was being a little nosey on them, e.g. risking going down the mine. So they were not exactly at 100% performance. but in those conditions, on Canaan, you would have been limited by pitching moment, not heeling moment. In other words, the boat would go over the handlebars long before it would fall over sideways for lack of righting moment. So really two years ago, our team was basically limited by how far back you could stand in the bus and still sheet on without stuffing it. so FYH was going about 25% faster on a VMG basis, even in those conditions.
Fast forward to even partial foiling. The bow simply doesn’t go down…..all that often. So when you get into waves the boat is basically just sailing straight through the water, through the back of a wave and out the other side with no heave, or change in altitude. The faster you go, them more stable it is because more and more of the weight of the boat is taken on the foils and if they are properly immersed all the time, the lift they provide is not changing all the time with each passing wave, so the boat is not pitching, it’s not heaving it’s just sailing. Now all of a sudden, you can start piling on some wing load. In retrospect that day I was being a pussy, I could have easily gone out on the wire and just hammered it on the sheet and we simply would have gone faster and probably lower.
Once you go to fully foiling, things change a lot, everything starts to go backwards as anyone who has sailed a moth will tell you. The puff hits, sheet in and step forward, don’t ease and stand back or you will go into orbit right away. So foiling means a bunch more complication on the boat. I think that’s one reason the C-cat crowd has followed the AC guys in not having “active” controls on the boat. If you can set up the geometry to create dynamic stability in flight, you save a whole lot of complexity on the yacht. Off Yer Rocker was a great execution of a stable foiling platform, but it came at the cost of a lot of bells and whistles. If you can fly with minimal controls and settings to sort out, it’s an elegant solution.
Back in 2011 at an ETNZ meeting, about the third big design meeting, some of the guys put up two intersecting curves showing drag in displacement and drag in foil mode and where they crossed over. Above a certain speed, downhill in particular it was obvious that the next cup was going to be won not with wings but with foils. At the time I was not sure if that would be the case for C-cats because by comparison they have a lot less horsepower. But seeing where we are now and the breeze the venue will hold its obvious that there will be ample power to foil for those that wish to.
The challenges however for foiling are many. One, you go really fast, which simply means you have the opportunity to land really hard, which with a wing can be really bad. kind of hurts the body too.
Stable flight, well it’s not all that easy without active controls like wands. Keep in mind the big boys have no less that one crew member dedicated to adjusting ride height with rake control etc on their main foils. We can adjust pitch and sheet far faster, but main foil angle is a big very important input for good flight. so a boat this size, needs an exceptional base line set up to foil happily.
Loads go way up. Upwind used to be our maximum load condition on foils, now it’s downwind. The foils are longer, way more loaded and so strength is an issue even with fantastic amounts of carbon and very careful build procedures, breakages happen. We have had some failures in shall we say, in very short time frames. It seems sailors are bred to destroy shit quickly. Then the loads on the platform go up too. When you fly a boat on a foil it has a ton of twisting force on the platform, this gets translated into the main beams which also now need to be stronger. everything is more loaded up now all the way around the course.
It’s very difficult to totally strip the system down to something as simple as our bench mark which is Canaan. You need to be able to adjust a bunch of stuff, much of it under load, to get a slippery, strong and controllable yacht. This all adds weight, complexity and cost.
Finally there is only two pairs of hands on the boat. The number of strings has gone way up, and new skill sets are required to operate the gear in a sensible fashion. It gets a bit taxing on the crew at times.
Flip side to all this, SCARY PERFORMANCE!!!! when the boat lights up OMG!!! hang on for dear life.
To answer your second question, how you trim the boat out, wait and watch, when you figure it out let us know too, we’re still learning a fair bit about it…
Meredith Block photos.
August 8th, 2013