ETNZ's flip...

That sucking sound

I pre-empt this article by stating this is just a theory based on watching the video along with knowing about some of the challenges other high speed sailing boats have had in the past.

It all started in the pre-start when BAR had ETNZ on toast, directly between them and the line with nowhere to go except straight ahead increasing the challenge of getting down for the starboard hand starting mark.

When BAR pulled the trigger ETNZ followed.

Now some have stated that the turn tripped the boat up but closer analysis of the video from the water and on board shows that Peter Burling had completed the turn and the helm was central when it all started to go pear shaped. As the boat accelerated it popped up on its foils as you would expect it to do with the increased lift due to the acceleration. Trouble was, it popped up too far, the foils got close enough to the surface and sucked air into the system. Perhaps a case of poorly adjusted foil angle/rake.

The well known problem of cavitation (ventilation – ed) (* SEE BELOW POST*) occurred and with air being a lot less dense than water, lift dramatically fell before the combination of 4 cyclists and a button pusher were just not enough to adjust quickly enough, the bows touched down and with a combination of a rig wanting to do 35 knots and hulls only doing 15-50 knots there was only one thing that was going to happen.

This is not of course a new problem, cavitation that is.

It was indeed the brick wall that Sailrocket 2 hit when attempting to set a new sailing speed record. Designer Malcolm Barnsley solved it by putting fences on their foils which effectively stopped the air being sucked down and destroying the hydrodynamics of the foils. And of course as we all know she, in the hands of her ‘pilot’ went on to set a record in excess of 65 knots.

A lot of damage to the boat, as you would expect from a relatively fragile covering hitting water at high speed but while the flappy mylar (or whatever they are using) may look dramatic it didn’t appear to have caused any structural damage.

Perhapos though the team coaches should spend as much time before the next race patching up any shaken confidence in the sailors as the shore crew will have to spend putting the boat back together.

Some people have said it is not a good way to win a yacht race but in reality it was an unforced error while sailing close to the limits for these boat. As they say – that’s yacht racing!

Shanghai Sailor

From Sailing Anarchy