Vestas Sail Rocket : End game...
Thursday, 15 November 2012
So here we are. VESTAS Sailrocket 2 has finally begun the big reveal of the beast within. From our perspective, the speed wasn't any accident and certainly wasn't unexpected. We have been working in this direction for a long time now. We always said that we were aiming for speeds over 60 knots and that in the current speed sailing context it simply wouldn't be worth building a boat unless you were. I don't think anyone is really sure of what the potential of the kiters really is. Even the windsurfers are now showing that they had what it takes to get well over 50 knots. Everything about VSR2 was focused on 60+. We just hadn't found the right combinations to unlock the boats real potential. Being stuck in the low 50's was frustrating on one hand but very educational on the other. To be fair, the new foil didn't get stuck there for very long. We just needed to get enough runs in to work through a few theories. The change in performance once the fences were added was pretty remarkable. The way that the low wind performance changed was a big indicator that something fundamental had changed and we were itching to see how it would effect us in stronger winds.
The last two runs were brilliant. That last run was truly great. It represented a real and undeniable breakthrough for sailing where the previous limiting factors were overcome. The good thing was that we did it in a pretty civilised manner on an open water course in winds that only averaged 24.5 knots on the shore station. I'm sure that we hit our peak speed in the high part of that average i.e. 28 knots but I'm also sure that that is about all we need to go even faster. The wind was ranging between 21 and 28 knots for those who are interested with a True wind angle of 99 degrees.
The target performance for VSR2 with these foils is 65 knots in 26 knots of wind. We figured that this should give us sufficient margin to get a 60 knot average and that we could make up for any unplanned inefficiencies by sailing in more wind if need by. You have to appreciate that you never get a solid 26 knot wind. Even on only a 500 meter run you might see 23 and 30 knots. At the true wind angles we are sailing we are bi-secting the gusts at a pretty rapid rate... not running along with them as you would on a deeper downwind course.
Now that we have looked at all the data we have seen that very little needs to be changed. The little 'yaw-string' wind indicator in front of the cockpit showed me that the fuselage was lining up with the apparent wind nicely. That's a good sign of the boats efficiency. The rudder loads and foil base pressures were all pretty good and the leeward pod was looking after itself nicely even at 60+ knots.
HE 500 Meter AVERAGE.
This was pretty interesting and gives a great indication for what is to come. The speed graph is more of a spike than a solid average. We were accelerating all the way from 47 knots to nearly 62 throughout the average. VSR2 was still accelerating hard when I finally pulled the pin and eased the wing. In fact she kept accelerating even as the wing was going out. I have no doubt she was on her way to a much bigger number if more runway was available... and quickly. When I saw the gust I knew I wanted it. I had to see what it would do. We were already going quick and accelerating. That last bit was like a turbo kicking in. I hung on for a couple of long seconds whilst my mind raced through the rapidly developing issues. I was happy we had broken into new territory but was also determined not to do anything gung-ho-stupid and destroy the foil. It was nearing low tide and flamingoes were standing in the shallows at the far end of speed spot. If I ran up there I could easily destroy the foil and end this record session. Fortunately the whole show was brought to a stop in the usual manner albeit with a little more distance involved. I knew it was 60. It had to be. It's what I imagined 60 would be like. Hard and fast. The ride firms right up and the chop turns into a rapid chatter. VSR2 just locks into a course and begins to feel lighter as the loads she is torn between get bigger and bigger.
So the peak was 61.92 knots (71.3 mph or 114.75 kph). The average was 54.08 knots over 500 meters and the best 5 second average was 59.08 knots. As mentioned, the low speed on the 500 meter average was 47 knots. Even if we don't go faster, it shouldn't be hard to bring that 47 up into the mid 50's. That should do the trick.
The thing is that I don't trust the kiters. They make me feel uneasy. They're hungry for this game and they are not going to give this speed mantle away without a fight. I'm not sure what their real limits are yet. For all this time we have been trying to bag this outright world record but even now... before we have even achieved that... I am wondering if that will make me happy. I guess this challenge has turned into something bigger than the actual record. With this boat we want to push the limits of the sport itself. The performance of the kiters has forced us to build this wonderful machine and to aim high. With that last run we entered a whole new world of performance. It's a fascinating world full of possibilities. In one way it is akin to when sailing boats realised they could follow their powered brothers from displacement mode to planing mode. Our new foils have many similarities to that analogy. They no longer have long thin transoms but are actually at their thickest there with the aim of getting the water to seperate cleanly. It's no longer just water down there but now it is air and vapour mixing in weird and wonderful ways. These can be played with using all sorts of 'bolt-on' devices. It really is fascinating. I've been lost in this world for the last year and am still only just realising how little I know about it.
So I expect the kiters to oneday reach an average of 60 knots. I don't know how or when... but that's what I expect. I'm not entirely sure of what their physical limits are but I know they are hungry. We want to get to a 60 knot average now. I don't know if mother nature is going to help us out here but we will be on standby for any and every opportunity.
As we sprayed the Pol Roger champagne over the main foil the other night I joked that I hoped that this was the only type of cavitation that this foil would ever see.
Only yesterday when we hosed it all off did I really see/feel a certain 'chalkiness' to the normally super-smooth surface near the tip of the foil and along the suction surface near the TE. I'm pretty sure that this is pitting caused by cavitation. The interesting thing is why we haven't seen this before i.e. when hitting the 'glass-ceiling' at 52 knots? It makes me wonder yet again about what we are looking at.
I'm now sure that we can smash the existing record. VSR2 has showed her hand and it's holding some aces. I will also be the first to acknowledge that we haven't done it yet. there's a heap of ways not to get the record out there. I still have that slightly edgy feeling that comes when you have it all to lose.
Despite our expectations, this is all new to us. Lying awake in the middle of the night and not having to wonder if the boat will ever really do it is a wonderful new sensation. I live and breathe this boat. It's great to be where we are at right now... with the expectation AND the knowledge. Yeah, we are aiming high... and yes I will be real happy when we grab that title for the first time.
One of these days this ride home is going to be that little bit more special.
p.s. thanks for all the messages of support and encouragement. I read them all and reply to as many as I can. Many of you have been backing us for a long time. You're all part of this snowballs momentum.
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Last Updated ( Thursday, 15 November 2012 )