Friday, 8 July 2011

Vestas SailRocket 2 and the Hydroptere

by Paul Larsen

Firstly we came back to digest what we had learnt about VESTAS Sailrocket 2 on her first trial session in Namibia. We had a team meeting in East Cowes where we went over the data and videos and discussed the real issues. The basic conclusion is that we simply need to spend more time experimenting with what we already have before we go and blow a lot of time and money on other options.

Getting the new foils to work is going to be paramount to the ultimate success of the project. We are all pretty confident that they will work at high speed but the real trick will be in getting them up there. The first time we trialled the new foil in full strength conditions, the boat accelerated up to the low twenties but when I pointed her down the course she just bogged down. We never got another shot in those conditions i.e. 25-29 knots average wind speed. I think that one of the issues may well have been that I simply sailed the same starting procedure I normally sail with the normal 'less draggy' foils. This involves running away from the beach to give me some room to turn up into the wind and accelerate before bearing away down along the beach in the nice flat water.

The fact is that the new foils are a lot more draggy at low speed and therefore the acceleration is a lot slower. I obviously wasn't going fast enough to be able to drag the wind forward with me when I turned down the beach. The acceleration stopped, the apparent wind (which increases and moves forward as the boat itself speeds up) stopped increasing and the wing stalled. I bogged down. The thing is that I don't get the full efficiency of the wing until I fully sheet the upper section in to 10 degrees at which point all the wing sections line up and no pressure is lost. I can't do this until the apparent wind (the actual wind that the boat feels which is a combination of 'true' wind and boat speed) is well forward. This can be done in two manners, by turning the boat into the true wind or/and going very fast. Right now I figure I should be doing much longer run ins towards the beach which will allow the wing to be fully sheeted in and the speed to increase enough so that by the time I get to the beach I should have enough speed and efficiency to bear away and keep accelerating.

Playing around with these start up profiles is the first thing we need to do

The next thing we need to do if this alone doesn't yield results is start adding 'bolt-ons' to the existing foil to try and increase its efficiency. We have a number of ideas at the moment which we are confident will reduce low speed drag. We started with a simple plain 'wedge' shaped foil and we will continue to use that as a foundation for our ideas. The fact is that it is made of some nice high modulus carbon fibre and we believe that by spending a hell of a lot more we would only make small gains in thickness and strength.

If this 'dog just won't hunt' then we will have to look at some completely different foils... maybe even an inclined 'T' foil. We aren't there yet.

We have had some interesting and constructive input from some of our other friends such as Richard Jenkins (sailing land speed record holder) and Chris and Richard from the 'Daddy long legs' foiling catamaran project. They all have significantly more experience than us with these types of foils albeit on different crafts with different problems. It's fascinating for us to listen to people who have real world experience dabbling in new frontiers. The fact that they are offering advice and lending their experience to us makes me happy. It means that we have a project that people feel good about and want to help. It really is appreciated and as always we will openly acknowledge all constructive input we get. These projects thrive on the help and input of outsiders so you really should make yourself as open as possible to it.


Hydroptere at speed. Image copyright Guilain Grenier/Hydroptere

So, in the mean time Helena and I have been spending some time on the Isle of Wight where we bumped into our old friends and one time adversaries from Hydroptere. They were over here chasing the elusive weather window for the Round-the-Island record. I was invited aboard for their last attempt which they tried in a strong Southerly wind. I was there to do Navigation and so got to spend a lot of time below in the flying room. It really is a mad boat. They tight reached up the Solent towards the needles in some gusty winds. We reached the Needles from Cowes in half an hour and then hit a nasty wind-over-tide situation which just slammed us in our tracks. My last entry in the log was "11:08 stopped"! I figured they would not push on due to the big messy conditions. Winds were already gusting to 30 knots.

To my surprise they pushed on with the beat up to St Catherine's. This took a long time and was a wet and messy affair. I gave them an easy angle to make it in to St Catherines to allow them a few options to avoid the lumpy tidal race that would be waiting there. Their only chance to hold onto the record would be if they could start banging out the big numbers from St Catherines on. I can't say they didn't try! We were all surprised at how hard they pushed that big, ungainly boat in conditions (now gusting to 35 knots from the South) through seas that would be rough for any boat. The foils were lunging through waves and dragging great pale aqua swathes of air through with them. She would get it all together and take off at 25 + knots only to go crashing into the back of another wave, slow down, take off again and then plant to a complete stand still further down the track.

Hydroptere had two reefs and a trinquette (stay sail) up so she wouldn't pitch too hard when she planted her nose into a wave. She would come to a standstill before popping up, shaking off all the water and taking off onto her foils once more. She actually felt pretty stable.

Hydroptere arriving in the Solent, by the Needles. Image copyright Christophe Launay/

By the time we got through the race we knew that the record was out of reach so Alain backed off the pedal. The rest of us looked at each other with raised eyebrows. That was some pretty wild and interesting sailing. Trying to go down below and look at a screen whilst all that was going on was a bit much for my stomach to bear. I had two snickers bars but I only ate one!

We enjoyed the rest of the sail home. Alain and I laughed about how hard we had pushed our respective craft in pursuit of the outright world record. Now that that particular battle is over I guess the glorious madness of it all has become apparent.

Once back in Cowes the sails were dropped, the engine started and we motored onto the mooring. Hydroptere had taken it all in her stride. I was very impressed by what I had just witnessed. That is one tough boat.


We also got the "black beauty" or VESTAS Sailrocket 1 out of her container and shipped her up to her new home at the new VESTAS R+D facilities up the Itchen River. The new sheds where the blade technology will be trialled is truly impressive. An open day was scheduled for the 2nd of July and we were to put the Mk1 on display. It's always good to bring her out and see how she is. Initially I decided to leave her as she was when she returned from Namibia to give people an idea of what a hard life she had had... but now that she is set for display, it was time to spruce her up a bit. The fact is that she was probably getting a bit tattier from storage than she was actually meant to be... so we sanded her down and gave her a nice fresh, thick coat of varnish. I tell you what, she didn't half come up alright either. I think she's a lovely looking boat with some real pretty lines but with the recent performance of VSR2 so fresh in my mind I couldn't help but recall what a hard time she had given us even to do moderate speeds. Either way, I love this boat and what we achieved with her. I can't bear to think she won't be sailed again.

So we put her on display and happily showed everyone who was interested everything there was to see. We had one vistor a few days earlier who is a fan of the project and high speed sailing in general. Jose is from Brazil and visiting the UK. He called up out of the blue and asked to come and visit. His timing couldn't have been better as we were setting VSR1 up. It was a real pleasure to show a real enthusiast around something he had been passionately following from afar. I made sure he got in the cockpit to get a real feel for her. You have to take these opportunities when they come. Great to meet you Jose and I hope one day I can show you around the outright world record holder.

Jose in the hot seat. Image copyright Vestas Sailrocket.

So both boats are in good shape as we wait for the winds to return to Namibia. the plan is still to head back in early september and keep looking for the right combination to unlock a whole new level of performance.

I'm off to do some more multihull sailing in Phuket next week before taking on a bit of a cycling mission across the French Alps when I return. I should be in good shape come September and champing at the bit for some big runs.

Vestas SailRocket 2