Sailrocket 2 - Getting used to 50 knots
by Paul Larsen on 21 Oct 2011
The team behind the Vestas Sailrocket 2 program are in Walvis Bay in Namibia to continue their quest to set the outright world speed sailing record.
Sailrocket 2 - getting used to 50 knots Vestas Sailrocket - copyright http://www.sailrocket.com
Well yesterday turned into a pretty wild day. The way the morning was unfolding we knew the wind was going to outperform the forecast.
Sailrocket 2 had up to now done four runs within a knot of 50 knots. Two over and two under. We weren’t sure if we had hit some sort of flow phenomena relating to the radical new foil around this speed. The team here in Namibia had been hurriedly collating all the data from onboard the boat and the shore to send it to the ‘brains trust’ back in the UK. As no two runs are the same we wanted to get a solid understanding of where we should be performance wise and what our areas of weakness are. As it stands, we feel we should be hitting peak speeds around 60 knots. The ‘brains trust’ aren’t that emotional... they just want good data and the understanding it generates.
As is often the case, the weather comes before the understanding and you just have to ‘wing’ it and get out there. We decided we wouldn’t change anything major and that we should simply try and get more information that would better define developing trends. It would be my job to simply do more clean runs down the course to generate more points on the graph.
When we got over to ‘speed-spot’ we noted that the wind was still very West. This means we get a small swell rolling down the course along with the wind chop. It also gives us a TWA of around 120 degrees which is a bit too downwind for us. When the wind started gusting over 26 knots I decided to do a shakedown run anyway. As The support RIB lowered me out onto the course I noted that I was actually pointing backwards up the course due to the offset fuselage angle of the boat. Nonetheless, Sailrocket 2 took off and I bore away down the course. She went well but lacked the big accelerating lunges that we were looking for. At the end of the course I only had to bear away a little for the speed to drop off rapidly. Obviously the TWA was too deep and the wing had been on the edge of stall. The team asked how fast it had been but I didn’t even think it was worth mentioning. It turns out we had once again hit 50 knots! I’m getting used to it now.
We towed VSR2 back up to the timing hut and decided to wait for the wind to settle further South. The day was building but it was very unsettled. We were getting wind ranges from 21 to 31 knots and swinging through 20 degrees. This wasn’t good for generating steady data. Nick had arrived back from the UK. He had landed in Walvis, caught a taxi to the Yacht Club, climbed into a Musto drysuit and was RIB’d across the lagoon to speed-spot still spinning. We waited for the wind to settle for an hour. It was improving marginally.
I decided that it would be a good opportunity to try out the back seat in Vestas Sailrocket 2. Adam from Wired magazine USA had been put in contact with us and wanted to come and see us try and break through the cavitations barrier. He has been living with us for the past month and watched our steady, solid progress. The actual 'Barrier' was proving very hard to define. Adam was leaving the next day so I figured it was the perfect time to try out the back seat. He seemed pretty keen. As we had never tried to sail the boat two up, I made no promises as to how it would go.
It was obviously windy at the top of the course. I really liked having someone else on board to share the sensation. I could feel the extra weight on the front float and knew this was the problem area.
With all the drag on the front float of VSR2, it resisted sliding sideways to help me bear away onto the course. I struggled to get the nose to bear away and every time I sheeted out to get the flow attached to the wing, VSR2 just turned more into the wind. I was now sailing back into the shore and running out of room. I way over sheeted the wing to windward to stall it and perhaps force the nose of the boat to bear away. With all the drag it stubbornly refused.
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I got Adam to release a small control line in the back cockpit which allowed me to over sheet some more. I also told him that it doesn’t look like it’s going to work. He reluctantly acknowledged this and already said thanks for trying. Slowly the boat began to respond and bear away. I told him to hold his horses as we might be on to a winner. Sure enough we managed to bear away and slowly slide sideways away from the beach. When I was happy that we were in a good position I eased the wing out to about 20 degrees and began the start up trajectory that allows me to straighten out the small front mounted rudder. This gets rid of a lot of drag and the acceleration begins. There was a lot more spray as the nose began to lift but already I knew we were going to get a run in. This was great. Someone else was going to join me for a wild ride down what was left of the magical mile that is ‘speed-spot’. My big concern was that we had already used up 800 meters trying to get started. This meant we only had about 800 meters left before we were into the shallows at the end of the course. There wasn’t enough depth for me to sail through these shallows with the foil down.
Vestas Sailrocket 2 accelerated a little more slowly... but then she hooked in. I was heading straight at the Timing hut and bore away onto the course. It was fast.
I was stoked that Adam was going to get a good ride. The leeward pod was already flying quite high as we shot past the hut at around 48-50 knots.
Then we bisected another couple of punchy gusts and VSR2 shot forward. I forgot about the passenger and focused on the situation rapidly unfolding before me. I don't think Adam had expected me to go flat out with him onboard. He was probably expecting a somewhat watered down ride. So whilst I'm going faster than I've ever been before, he's in the back doing this...
The boat was smoking and I wanted to ride the gust to get the 500 meter average. Things were coming up quick. I eased the wing and bore away but VSR2 hardly slowed down. I was now out of runway and had to take evasive action so as not to hit the shallows at speed. At around 45 knots I swung into a hard right hand turn into the beach and wind. It was a long hard turn that the boat actually accelerated into as she smoked through her own ‘power window’. I knew I was in shallow water and started to try and release the main foil pin before we settled down to allow it to kick up but we slowed too quick. I felt the foil start to plough the thick mud and shell bottom. Not nice when the leading edge is a thin sharp edge as it is on this foil. We slowed quickly and stuck. I knew the situation wasn’t yet under control and could even escalate from here. VSR2 was floating and only the main foil tip was stuck. The grounding hadn’t been very hard so I doubted any serious damage. The RIB took ages to get to us as I tried to free the foil. I looked back at Adam and he was just wide eyed and looking at me for my response as to what had just happened. He had seen the GPS just in front of him. I was still concerned about the boat. As I tried to get things sorted I could sense Adam trying to draw my attention to the GPS. He wanted to know what the 53 number meant. I kept focusing on the boat but he persisted wanting to know what had just happened... how fast was that. 'What had I just witnessed'? Eventually I jumped in the back cockpit and checked it out. 53.92 knots and a 50.05 500 meter average (54.4 on the processing and 50 even for the 500). It quickly dawned on me what had just happened. I told Adam that I had spent a great part of my life trying to sail on the fastest boats in the world... and in one ride he had been as fast as I had ever been. He was stoked. He had seen speed sailing at its best. He really hadn’t expected me to go that hard with him in the back. Neither had I really... but when your gust comes along... what are you going to do?
That was our first ever 50 knot average run... and it was all pretty easy. I had a 75kg passenger sitting up in the back waving and none of the extra aero aids onboard. The wing wasn’t fully sheeted in as the pod was already flying high and that would just make it go higher. I could easily see where another 5-8 knots would come from. VSR2 had beaten VSR1’s best ever run and she is still getting warmed up. I know now that we have a real contender. The kitesurfers are no longer the undisputed kings. They are the hunted. I know we haven’t done it yet but with every run our confidence grows. We were all buzzing as the thrill of a big run and what it represented began to sink in. The foil damage was only cosmetic. It’s one tough boat. Adam came to the breakfast table still smiling and was still buzzing as he got on the plane later today. He couldn’t have hoped for a better experience... short of going 60 of course.
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So, what does this mean for where we are at now performance wise?
The wind was between 24 and 29 knots on that run as you will clearly see on a video Helena is putting together now. The extra speed probably came due to a strong gust around 29 knots. I think we are still underperforming but not by a huge margin. We can only improve on this with refinement. Like I said, there were some easy gains to be had there.
We built VSR 2 to be a tough and rugged boat up to the job of sailing in 30 knots of wind. She is doing this admirably. Refinement takes time and sometimes you don’t have it... but you do have lots of wind. If we can bludgeon a world record out of a top-end windy day just using brute force then so be it. The final speed is what counts. We are already demonstrating that we can sail hard on top end days. It’s the apparent wind speed that will ultimately count, not the true wind speed. So, from this point I believe we can beat the current world record. I know we will continue to progress and that 60 knots isn’t that far away. We believe that the new foil will keep delivering the goods at speeds where conventional foils will get marginal. We do still have the conventional foil and are looking forward to seeing just how far it can be pushed. We will do that soon.
The rate of progress has been staggering. We barely have time to collate and assess the data before we have moved on a substantial amount and generated a whole new pile of data. We believe that our performance is directly attributed to the unknown performance of the foil. We will continue to work on ways to make it perform better and it is entirely possible that we can make it perform a lot better. Simply put, in our crudest form sailing at our design maximum wind speed, we are already in the ball park. It’s an exciting prospect. I personally want to see at least a 65 at some stage of the game.
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Ratified World Record attempt coming
So we have begun discussion with the WSSRC and it looks like we will start our attempt on the 17th of next month... maybe sooner (The price has gone up by £500... probably for some ISAF party absolutely essential to speed sailing). This will be immediately after the kite surfers record attempt down in Luderitz. It seems like an odd event. Why aren’t Rob Douglas and the other guns invited? Oh well, hopefully we can bring the Outright record a few hundred kilometres further North. Either way it’s going to be a big couple of months for speed sailing in Namibia and one way or the other the record will stay here.
The next weather window looks to be around next Tuesday. The wing skins had split in places indicating that they were perishing from the UV. If you can give the skins a hard flick and they split/shatter… it’s time to change them. We have taken the wing off again and will give it a serious makeover. We will also work on all the seals between the sections to reduce any pressure leakage. Some of the aero fittings will start going on and more weight will be taken off as redundant systems are removed. Piece by piece we will build a record.
Cheers, Vestas Sailrocket 2 website
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