speed sailing issues... defining the apple!
Here's what we think on recent issues including Tilman's runs. I do have opinions on certain issues and hope that they are seen in the constructive context with which they are put forth.
The whole idea of the WSSRC from its inception was, to borrow a phrase, 'to compare apples with apples'.
The majority of these 500m claims using hand-held GPS systems is for 500m travelled on the water, not in a straight line i.e. if you run at 50 knots in a zig-zag course down a 500m course, you may be doing 50 knots but your average will be less. Rightly or wrongly, this is simply how it is done.
I personally feel that this is the correct way as I believe that the 500 metre course is there to demonstrate a controlled and sustainable average. To show that a relatively steady state has been achieved.
Another issue worth raising whilst on the subject of 'Apples with Apples' is the one regarding depth.
The rules currently don't state any minimum. It is only a matter of time until the rules, or lack thereof, regarding the 500m Outright record course come into question. Whilst the rules for open ocean records are pretty straightforward, the Outright record rules are not.
I would like to think that the pursuit of the outright record is a pure demonstration of the relationship between a craft, wind and water... nothing else. It is the essence of sailing. This breeds the amazing diversity of expression currently attempting the outright record.
Hydrodynamic 'Ground effect' in relation to the bottom is a phenomenon simply not available or practical for most other craft and the WSSRC's position on it should at least be stated.
Is there a limit?
As the WSSRC are the body governing these attempts, it is their responsibility to put the endeavour on a firm foundation by removing much of the vagueness and defining the 'apple'. Sounds easy... maybe not. It will probably mean that they will have to define a sail boat by setting parameters i.e. a balloon in a gale dragging a line in the water is one extreme not currently outlawed. Considering the current debate over a simple term like 'keel'. This represents a minefield!!!
For teams like ourselves, these rules will determine our future directions and we would like some form of certainty so as to remove any confusion or dispute which will inevitably arise.
Tilmans speeds are nonetheless very impressive, he probably did go faster than the current world record but probably didn't do 50 knots over the standard 500m course. I would shout about it too... and then I would quickly call the WSSRC to come and ratify it to remove all doubts. It is done like that for a reason.
No one likes the cost and hassle currently involved with ratifying this record but independant ratification is the only way to do justice to the title.
There is currently alot of activity surrounding the Outright record. There is also plenty of debate from all angles. It all seems healthy and constructive.
The Sailrocket project will resume its sailing program in Namibia this month. Whilst we aim to do 50 knots, our overall aim IS to be the outright fastest. If the kiters do 50 or 55 knots we will keep going.
Whilst the current Sailrocket is a Mk1 prototype, part of the reason we chose the concept underlying it is because we know it has the ability to be realistically developed for much higher speeds. If we can do 50... then we believe that we can do 60.
Cheers, Paul.
The whole idea of the WSSRC from its inception was, to borrow a phrase, 'to compare apples with apples'.
The majority of these 500m claims using hand-held GPS systems is for 500m travelled on the water, not in a straight line i.e. if you run at 50 knots in a zig-zag course down a 500m course, you may be doing 50 knots but your average will be less. Rightly or wrongly, this is simply how it is done.
I personally feel that this is the correct way as I believe that the 500 metre course is there to demonstrate a controlled and sustainable average. To show that a relatively steady state has been achieved.
Another issue worth raising whilst on the subject of 'Apples with Apples' is the one regarding depth.
The rules currently don't state any minimum. It is only a matter of time until the rules, or lack thereof, regarding the 500m Outright record course come into question. Whilst the rules for open ocean records are pretty straightforward, the Outright record rules are not.
I would like to think that the pursuit of the outright record is a pure demonstration of the relationship between a craft, wind and water... nothing else. It is the essence of sailing. This breeds the amazing diversity of expression currently attempting the outright record.
Hydrodynamic 'Ground effect' in relation to the bottom is a phenomenon simply not available or practical for most other craft and the WSSRC's position on it should at least be stated.
Is there a limit?
As the WSSRC are the body governing these attempts, it is their responsibility to put the endeavour on a firm foundation by removing much of the vagueness and defining the 'apple'. Sounds easy... maybe not. It will probably mean that they will have to define a sail boat by setting parameters i.e. a balloon in a gale dragging a line in the water is one extreme not currently outlawed. Considering the current debate over a simple term like 'keel'. This represents a minefield!!!
For teams like ourselves, these rules will determine our future directions and we would like some form of certainty so as to remove any confusion or dispute which will inevitably arise.
Tilmans speeds are nonetheless very impressive, he probably did go faster than the current world record but probably didn't do 50 knots over the standard 500m course. I would shout about it too... and then I would quickly call the WSSRC to come and ratify it to remove all doubts. It is done like that for a reason.
No one likes the cost and hassle currently involved with ratifying this record but independant ratification is the only way to do justice to the title.
There is currently alot of activity surrounding the Outright record. There is also plenty of debate from all angles. It all seems healthy and constructive.
The Sailrocket project will resume its sailing program in Namibia this month. Whilst we aim to do 50 knots, our overall aim IS to be the outright fastest. If the kiters do 50 or 55 knots we will keep going.
Whilst the current Sailrocket is a Mk1 prototype, part of the reason we chose the concept underlying it is because we know it has the ability to be realistically developed for much higher speeds. If we can do 50... then we believe that we can do 60.
Cheers, Paul.
posted by Paul at 4:44 pm
4 Comments:
Dutch people have a name to be blunt but fair, a bit too blunt for some people's taste, but it is always ment well:
Is there any scientific data about the hydrodynamic ground effect and is can it be put into numbers when the depth of the water of Tillman is measured and the wet surface of a kiteboard is estimated.
Personally I only feel the extra lift of shallow water when I'm kiting when the fin is almost touching the ground.
I really believe the flatness of the water is the cause for his speed not the shallowness of the water. Give him the same flat water of any depth and he will get to 50 as well. But that kind of watre is hard to find.
Second I think that of course the non heeling concept is faster than kiting. But what it comes down to I think is how you bring the concept into practice. And Sailrocket as I see it, is not the ultimate version. Monofoil is, as far as ideas go for now, but it still isn't finished. So you have a gap: Overtake the kiteboarders before you will be overtaken by monofoil.
But I sincerely hope you'll get the record even if it would be for a period, you have really deserved it. You have set the path for the concept and for a complete new dimention in speedsailing. Very bold and innovative. You are one of the hero's of speedailing no doubt !
Cheers,
Johan
I like the debate. In airplanes ground effect becomes significant within about a wingspan's height above the ground. My friend and coworker just bought a little RC helicopter which does a great job of demonstrating this phenomenon. It will settle into a hover about a rotor's span above the ground without any throttle adjustments necessary. But anyways, as it applies to hydrodynamics I'm guessing the appropriate reference height (or depth in this case) would be relative to the board length. If you have a 5ft long board, it should be in water that's about 5ft deep. Oddly enough though, ground effect matters less the faster you go because parasitic drag (friction) begins to dominate. In any case, based on what I've read so far, I think Tilman's run was in ankle deep water, which definitely has a significant impact.
I'd be more concerned about the accuracy and validity of the GPS measurements though. In no other sports is GPS used as a speed measurement device. Speed is always electronically timed (using video or RADAR). I found this link below which makes the point that other sports, such as track and field, follow curved paths, so why not sailboats? http://www.sbckiteboard.com/News?news_id=342&uniqid=1015
That's clearly an incorrect analogy because all the runners are still timed on a fixed distance, namely the length of the track. An equivalent analogy to a track on the water would be for a kiteboarder (or some other boat/boarder) to follow a curved path a around a set of buoys.
In any case glad to see Sailrocket is back on the blog. I wish you the best in Namibia. I can't wait to see some conceptual drawings of the Mk2 version.
And speaking of Monofoil, anyone have any updates? I've tried emailing them but it keeps getting returned. They haven't updated the site in about a year I think.
Also any links with more details about Tilman's kiteboard run would be much appreciated.
And as you guys say over there,
CHEERS!
When wingspan is a measure in planes it will problably be the width of the wet surface, or probably the wet surface in total of a kiteboard that is important. And at that kind of speeds it is not more than something like a square feet.
And the extra friction at high speeds sounds very plausible, ships are also towed down in shallow water.
Would like to here an expert on this.
You bring up a good point, namely that the width of the wetted surface area would be the counterpart of wingspan from the aerodynamics domain. That makes sense.
But most, if not all, boat hulls have longer waterline lengths than they do beam widths, and they tend to be much heavier than their airborne counterparts. This means that other factors, like length and loading, probably have more influence on the ground effect (or is it "bottom effect") than does the width of the wetted surface area.
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