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Mako wrote: Rob you have to be kicking the rudder left and right as you paddle. Your tail was flipping in time with your stroke all of the time I rode your wash. I also noticed the 'hard looks' you cast in the other ones direction as he maintained a healthy lead over you.
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What a terrible thought - I'm off to adjust my rudder pedals right NOW!Just realised you were TWERKING!
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Dale Lippstreu wrote:
The boats we are talking about have these figures:
Epic New V10 45 x 645
Fenn Swordy 45 x 610
CK Focus 46 x 642
Knysna Blu 46 x 620
Think Evo II 48 x 625
The width to length comparisons are interesting and worthwhile but I suspect they may be of limited value unless the measurements are done at the waterline.
The worthwhile bit comes in the form that the aspect ratio (length divided by width) of a hull determines how much energy has to be inputted to maintain a given speed. If we take for example a ski 6m long and 44cm wide travelling at 3 metres per second (10.8 km/h) a water molecule encountering the nose has be deflected outwards 22cm (half the width of the hull) in 1 second (the time the molecule takes to reach the middle of the hull (assuming the widest point is at the middle). Very roughly (and excluding a lot of details) the energy that has to be imparted to the water to part it as the ski moves through the water equals the energy required of the paddler to maintain the speed of the ski. In principle then if we ignore practicality and other effects such as skin drag etc the drag halves if we double the length of the ski.
The aspect ratio is therefore a very useful measure for predicting the speed of a ski and the numbers provided by owenfromwales produce the following ranking:
Ski Width Length Aspect Ratio
V10 45 645 14.333
CK Focus 46 646 14.043
Swordfish 45 610 13.556
Knysna Blu 46 620 13.478
Evo ll 48 625 13.021
The problem I have with the result is that the measurement are almost certainly taken on the deck and may be very different at the waterline. I strongly suspect that the Evo ll is much narrower than 48cm at the waterline and therefore a lot faster than shown on a relative basis.
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