by Paul Larsen
The team behind the Vestas Sailrocket 2 program are returning to Walvis Bay in Namibia to continue their quest to set the outright world speed sailing record.
Here we are, direct from the first day of our first world record attempt with Vestas Sailrocket 2.
Mike Ellison from the WSSRC is now on-site to watch over our upcoming attempts.
We had to commit to this attempt around a month ago due to the rules of the WSSRC. We were hoping to be hitting world record speeds before booking a record attempt but we aren't quite there yet. We are close in some ways but still yet to convert. Nonetheless, I am entirely comfortable with commencing the record period now and believe that we have every chance of success.
On our last run we ventured out in over-the-top conditions and did it with ease. Of course we were hoping for higher top speeds but in hindsight what we demonstrated was the capability of the boat and team to operate in all conditions. from here on in the rest is down to refinement.
Whilst most casual viewers will just look at the final speeds, so much of the big problem is making a boat that can be handled safely in every other situation that will allow it to get into its ideal operating environment. Putting a wing up in waste deep water on a windsweapt beach with winds over 30 knots can very quickly go wrong if you are not in control. It is often the fear of this that stops you from doing it. We no longer fear this which means we can now pour on the free power of stronger winds if we have to. One problem here is that with stronger winds comes bigger chop. Vestas Sailrocket 2 copped a real pounding on that last run. Every part of the boat got jerked, flexed and wrenched and yet she was stable and in control throughout. She's a tough boat as she is made for much higher speeds.
So, refinement eh? It would appear that what we did on that last run was simply throw a heap more power into the equation... but not go any faster. This would suggest that we have hit a wall. The speeds of around the low-50's would suggest that there is some sort of cavitation happening that is not ideal. I say 'ideal' as the new wedge foil is designed to utilise either cavitation or ventilation. I believe that there is a whole world to explore between the attached flow of water we are used to on conventional foils and the other extreme of fully 'super-cavitating' sections where a bubble of air in one form or another breaks off the low pressure side and extends way past the the back/Trailing-edge of the foil. From a hydrodynamic point of view it's pretty fascinating.
In a way we are trying to make the new foil lose 'grip' with the water on one side... but we don't think it is. We have now added a little ridge on the back of the foil to help trip the flow of water off it. In some ways it's like driving sideways in a car. In order to get into the best sideways cornering mode you need to trip the car to make it lose grip and slip sideways initially. You need to jerk it out of balance.
In our case we don't want to make the flow so messy that it destroys our low speed performance so much that we can't get going. We need to play with the size, shape and position of this little 1mm high ridge so that it trips the water at just the right time. Well, we are very well placed now to play with this. VESTAS Sailrocket 2 has put us squarely in the laboratory and all the ingredients are in place. The boat is right and the foil we have is a great starting point.
We must also keep our eyes open for what we may be missing. Sometimes there are silly, basic things that you look back at and can't believe you missed. This is where all the video and data collection becomes so vital. Every time you watch a video you see something different. It might be where the spray is hitting or the angle of the wake. There is just so much info there.
Anyway, here we are... and it feels good. I am always nervous about the little gremlins that can creep in and undo all your hardwork in an instant. We have extended the tail of the boat by 1 meter to increase the shroud base and make it more stable whilst rigging and launching. This process has enabled us to change all the rigging (thanks Marlow), remove any unnecessary items and add dormant safety features throughout. We will continue to go over the boat every day.
The kitesurfers in Luderitz have finished their attempt. We have a complex boat, they have a complex course. The record we are chasing remains that set by Rob Douglas at 55.65 knots.
Are you getting the impression I want it? Good:)
Latest update: Flat calm today, we might get an easy shakedown sail tomorrow. Monday still looks best!
Vestas Sailrocket 2 website