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Old 4th June 2012, 03:26 PM   #25
Jean-Marc
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Join Date: Aug 2006
Posts: 1,341
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Here is the link to the report that "unregistered" was kindly talking about on another thread:

http://www.sailweb.co.uk/download/Ki...icalReport.pdf

ISAF Kiteboarding Format Trials Santander, Spain, March 21-25
Technical Report

Page 5 of 33:

"Performance:

Equipment can be launched in app. 3-4 knots of wind, depending on current, wind variety and surf.

Kiteboards can sail and be immediately on the plan from 4-5 knots.

GPS analysis showed the following speeds and angles in 6-9 knots:

Speed on the Beat: 15 knots or 8 1⁄2 minutes /nm
Speed on the Run: 23 knots or 4 minutes /nm
Speed on the Reach: 26 knots or 3 1⁄4 minutes /nm"

On the GPS recording shown as "proof", there is only 1 event with a Vmax peaking at 26 knots and maybe another one at Vmax 24 knots over a period of 2 hrs. Was the wind gusting at more than 9 knots during those 2 Vmax peaks? Where was the wind being measured : on the beach, on the course or at a nearby airport weather station ?

The "proofs" shown in the report are highly questionable to me simply because some of my kitesurf friends are unable to reproduce some of the miraculous claims made in this report on our home lake.

1) "Kiteboards can sail and be immediately on the plan from 4-5 knots". Yes, that is correct but only in true 5 knots winds with a Speed 3 Flysurf 21 m2 kite and a XXL Flydoor board (170cm x 50 cm) or a tube 22 m2 kite and a custom Kite Race board equipped with 2x 40 cm long race fins forward and 2x 36 cm long race fins on the back. Below 5 knots, it's swimming time and rescue boat help on our lake.
With a standard equipment (a basic twintip board), the wind limit is more like 7 knots with an 18 m2 kite or 10 knots with a 12-14 m2 kite. On par with a standard Formula Windsurfing equipment.

2) None of our group of 20+ kiters can reach a board speed that is equal to 3-4x that of the wind speed in winds below 9 knots. Only specifically designed large cats can do that on our lake, as explained below.

Furthermore, to claim that "The class polars show that kiteboarding is one of the most performant of all sailing classes, including the AC 45 and Extreme 40s" is overly measleading and represents a gross oversimplification of what the reality is on the water.

In 7 knots wind, a Decision 35 cat can reach a sustainable speed that is equal to 3x the wind speed on our home lake. In that same wind speed, the defunct Alinghi 5 mega cat was reaching a sustainable speed of 28-30 knots, i.e., 4x that of the wind speed. Sorry, I just don't buy that silly argument that "kiteboarding is one of the most performant of all sailing classes". Not true.

No wonders why windsurfing is out of the olympic games with such a blown-up-on-steroid report. Go figure...!

Cheers !

JM
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