I think someone needs to talk to the Shark Bay salt mines to get a channel cut in for this purpose.
Definitely a consistent wind up there during summer
Select to expand quoteStuthepirate said..
I think someone needs to talk to the Shark Bay salt mines to get a channel cut in for this purpose.
Definitely a consistent wind up there during summer
I think the kitesurfers already have :)
Even the perfect ditch won't help much because windsurfing speeds have
already reached the point of diminishing returns. The only record likely to
be broken from this point in time is the number of sailors injured or maimed
each year.
The following reference is a forum discussion of how close water speeds are
to ice speeds (note that the surface drag on ice is much less than on
water): www.gps-speedsurfing.com/default.aspx?mnu=forum&forum=1&val=36081
FWIW the following article in Catalyst, entitled 'Hyperwind Sailing', offers an
explanation: www.ayrs.org/Catalyst_N06_Oct_2001.pdf
Icespeeds are close to waterspeeds but you have to put into perspective in what kind of conditions both are sailed. Albeau's record has been sailed in 40 to 50 knots windspeed in a special trench.
If you take a look at the rankings on www.gps-icesailing.com/default.aspx?mnu=rankings you will see a lot of Dutchies reach 80+ and some even 90+ avg's. I have to point out that when we've got ice overhere we are generally in calm weather and have either northerly or easterly winds. These winds generally never exceed 20 knots and in gusts might reach 30 knots.
If you lookup Pieter Hamstra, Gerlof Hansma or Peter Vernet on GPS Speedsurfing you will see hugh difference in speed between ice and wind. Having a bit of knowledge about the places these guys icesail I can tell you that there is no way as much space as in the Youtube clip posted by Mathew.
Also if you look at the sailsizes used you will see the icesailors use anywhere from 4.5 to 6.5 sails in moderate winds. When windsurfing in the same windspeeds you generally use sails up to 2 m2 bigger.
I rekon if there's enough space, constant windspeeds over 30 knots and some top GPS speedsailors the ice record will be much higher!
Select to expand quotebarney831 said..
The suffix hyper means over, above or beyond. Hyperwind is just a discriptive term that I used for the contents of the article. Unlike many dimensionless ratios in science and engineering, there is no commonly accepted name for the ratio of board/boat speed to the wind speed. I like the term Foehn Number for this ratio because Foehn is the name of a type of wind. There is no precedent but you're welcome to use it if you like.
In a steady wind, there is an optimum angle off the wind where maximum board speed is reached. The rule of thumb 'deeper is faster' only applies up to the optimum angle; beyond that deeper is slower. The optimum angle is mathematically tractable and can be found with a good performance predication model. Overpowered iceboats commonly turn downwind to slow down.
Foehn Number sounds like a reasonable description... usually in sailing it may be called Downwind-VMG ( Velocity Made Good ), but that doesn't convey the same meaning as the Foehn number. As we have seen with SailRocket, it is possible to achieve FN > 2 while travelling at high speeds (the website says just on 30kn windspeed).
Regarding the iceboats turning downwind - is that more an artifact that most of them are built like a yacht (ie: with a boom that cannot pivot around the front)... if they were to round-up, they would topple over?
Select to expand quotemathew said..barney831 said..
The suffix hyper means over, above or beyond. Hyperwind is just a discriptive term that I used for the contents of the article. Unlike many dimensionless ratios in science and engineering, there is no commonly accepted name for the ratio of board/boat speed to the wind speed. I like the term Foehn Number for this ratio because Foehn is the name of a type of wind. There is no precedent but you're welcome to use it if you like.
In a steady wind, there is an optimum angle off the wind where maximum board speed is reached. The rule of thumb 'deeper is faster' only applies up to the optimum angle; beyond that deeper is slower. The optimum angle is mathematically tractable and can be found with a good performance predication model. Overpowered iceboats commonly turn downwind to slow down.
Foehn Number sounds like a reasonable description... usually in sailing it may be called Downwind-VMG ( Velocity Made Good ), but that doesn't convey the same meaning as the Foehn number. As we have seen with SailRocket, it is possible to achieve FN > 2 while travelling at high speeds (the website says just on 30kn windspeed).
Regarding the iceboats turning downwind - is that more an artifact that most of them are built like a yacht (ie: with a boom that cannot pivot around the front)... if they were to round-up, they would topple over?
Hi Mathew,
At high Foehn Numbers the apparent wind is alway coming from a few degrees off the nose of the iceboat. Unlike softwater sailboats the range of sheeting angles required is quite small. The point that I was trying to make is that headings upwind or downwind of the optimum heading for maximum speed are slower.
