|OCTOBER WAS A BAD WEEK FOR KITEBOARDING.
Wasn't it ever! The Vestas Sailrocket
In May 2012, the International Sailing Federation (ISF) decided that kiteboard racing would replace sailboarding (windsurfing) for the 2016 Rio Olympics.
This was a big deal; within weeks, a preference for course racing rather than wave riding/jumping swept the world of kitesurfing; or at least it did at the popular kitesurfing spots like Scheveningen beach in the Netherlands and Poeto beach in Sardinia where I've been recently.
On November 9th 2012, at the ISF's annual meeting, a proposal to re-open this decision failed to get the 75% council support required for it to go before the delegates and kiteboarding was confirmed for Rio.
But, the very next day, (10th November), the ISF reversed it's May decision, removing kiteboarding and reinstating sailboarding. There must have been some intensive lobbying during the evening of the 9th!
The proposal put by the International Raceboard Association (sailboarders) was that kiteboarding; "---has not proven to be ready for inclusion in the Olympic Sailing Regatta" and passed narrowly -just 51.3% support.
It's a serious setback for kiteboarding, but there are very good reasons why we can expect this to be temporary in the longer term.
Not least of these is that kiteboard racing places a premium on skill and athleticism- which positions it centrally in the Olympic ideal.
And that kiteboards are now arguably the fastest way to get around an Olympic sailing course doesn't hurt our cause either- and being such a new idea, in the next years they are for sure going to be even faster and more spectacular relative to traditional sailing classes (including sailboarding).
Hopefully a case of "whatever doesn't kill you makes you stronger"!
But then, on 20 November, at Walvis Bay in Namibia, "Sailrocket", a purpose built asymmetrical (starboard tack only, gets towed back for the next run) speed sailing yacht set a new outright world sailing speed record over 500m of 59.23knots. The previous record of 55.65knots had been established in 2010 by kiteboarder Rob Douglas, also in Namibia. Namibia is favoured for it's relatively reliable and smooth offshore winds (no waves). Larsen and the Vestas Sailrocket at high speed - 2012
Sailrocket sailed a 'natural' course at Walvis Bay- though close up against the beach to take advantage of flat water.
Rob's 2010 record was set at Luderitz, 600km north of Walvis Bay, on an artificial course; a trench excavated through a flat beach area (an idea pioneered at Saintes Maries de la Mer in the '80's for speed sailing).
And then, for kiteboarders, it became much worse, and for hydrofoilers and sailboarders, terminally so I reckon.
On the 24th of November 2012, Paul Larsen in Sailrocket raised the record to 65.37 knots (not yet ratified, but expected to be). This is a 17.5% step. The previous largest incremental change in this record was back in 1973 when Tim Coleman in Crossbow raised his 1972 record by 11.4% to 29.3 knots. More usually, increases have been tiny (Rob Douglas improved on the previous record by just 0.003% in 2010).
Here's a table of sailing speed records from 1972 until now:
Please visit the full story: [click here]
You'll notice that it took 20 years (1988 to 2008) to get from 40knots to 50 knots, and there's a reason for this.
At around 45 knots or so, conventional fins 'ventilate'- that is, the water flow on their low pressure side can no longer be persuaded to follow an airfoil shaped curve. That this happens is pretty much an immutable law of the universe. Very careful shaping, highly polished surfaces, and delaying onset by sailing in the smoothest of smooth water can keep flow attached up to the mid forties, maybe even 50 for deep fins (ventilation resisting pressure increases with depth).
But above 50knots; fins ventilate. This is a fact of life- you just have to live with it.
Unless you use wedge shaped fins (like a sushi knife, sharp edge forward). Wedges don't ventilate, but they have much more drag, same difference.
Ventilation or wedge, take your pick, but the drag basically doubles at 45 knots or so.
This is an especially terminal condition for hydrofoilers (like l'Hydroptère to the left here), because they use foils not only to resist the lateral force of their sail, but also to hold themselves up. l'Hydroptère DCNS
And for sailboarders who require an extra margin from fin efficiency to offset their inability to rest sail heel.
With either a ventilating foil or a wedge, the driving force supplied by the sail (or kite) must approximately double to maintain the same speed. This is why the sailing speed record has hung around in the 40's for so long.
But once this barrier has been surmounted (by improving aerodynamic efficiency, but mainly by innovations in layout and structure), incremental improvements in sail/kite effectiveness will once again lead to commensurate increases in speed. 100mph anyone?
And this is what worries me for kiteboarding; Zero Heel Board November 2012Gavin with a big grin
There are plenty of ways that specialist speed sailing craft like Sailrocket can increase their sail driving force; by going wider, bigger, more streamlined and etc.
But kiteboarders have intrinsic limitations imposed by their basic layout.
Specifically, kite pull is significantly out of alignment with the board's edge (where sideways pull is resisted).
To go faster, kiteboards will need to become kite boats, with the rider sitting down (in an aerodynamically faired cockpit) and with the kite pull applying through a linkage system that aligns its pull with hydrodynamic lateral resistance (ventilating fins, wedge fins or angled planning surfaces).
As per the images to the right, which, quite coincidentally we tested for the first time last weekend.
Sailboarders?- nah, they're history- also for the Olympics I reckon.
Peter Lynn, Ashburton, New Zealand, November 30, 2012.
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