>>To Wouter: The specs I have seen and a witness say that the M20 is about 9.5' beam. What is your statement that it is 8.5' beam based on? If 8.5' beam for the M20 is an error, wouldn't that substantially change your analysis of the boat?

I confirm that 9,5 feet is the right number and not 8,5 mtr. I have seen quotes from 2,6 = 8,5" to 3,0 mtr = 10" in the past but Texel just remeasured the M20 and it found 9,5". (I know it is not used in the system, but it is measured anyway)

Does this change the analysis. In relation to 8,5 mtr. boats "may do so, yes", I relation to the 10" wide Tornado, no.

This dependent on which reference we agree upon.

My argument was based on choosing a reference platform and modifying it. Than to make conclusions on what to expect as the result of the mods.

Take a tornado and lets make it lighter en less wide. This will lead to a boat likely to preform worse in trap condition. If the Tornado is made lighter but keeps the same width than it is has a good change of performing better.

However all is determined by the magnitude of the changes. 1 inch width reduction and 100 lbs weight reduction will have a different outcome than say 2 feet width reduction and 1 lbs weight reduction.

And here is where the main point of my argument is to be found. All of these aspects are linked ; the net effect of a certain reduction here is partly determined by a reduction (or increase) somewhere else. So when modifying important ratio than the ratio between the ratio itself is also important.

In this sense the statements made by Bill about width and weight are a subset of the more general case that I expressed. Bills way of improving speed is correct but it is not the only way of improving it. And there is the casue that started the debate between him and me.

In simplere analogue terms.

Bill argument is analgue to claiming that to go faster in a car you must use a bigger engine and preferable place it further back to put more weight in the driven wheel to avoid slipping.

My argument said that you could go faster with an even a smaller engine than before and also keep it in the same place as it was when you are succesful at sufficiently reducing forms of drag or resistance to acceleration. Examples of this are lighter wheels and a lighter flywheel in the driving system (not a lighter car ! mind you) or even reduced frontal area to reduce aerodynamic drag which reduces the amount of power available for accelerations/speed.


In the first example you increase the important factor that caused speed or accelleration. (Brute force methode)

In the latter example you analyse and try to optimize the ratio between important factor in such a way that the overall governing ratio is improv ed. Of course the first example implicitely does the same trick but without explicitely refering to it or even knowing about it.

On the starement of :

>>recently stated that the power (force, KW, hp) in the wind varied as the square of the velocity of the wind. My old DOE manual for home windmills gives a formula for wind power that has a cube on the wind speed. And that is the understanding most my landsailing buddies have. Did I misunderstand your statement?


The energy contained in a GIVEN (and constant) volume of fluidum is relative to the windspeed squared.

The energy contained in a volume of fluidum flowing through a given (and constant) stationary area is relative the windspeed to the 3rd order or cube.

Of course both windmills and sails are more closely described by the second case. When the wind blows harder than a bigger volume of fluidum is blow past the energy harvester which are sails and windmill wings. This volume increases lineairy with windspeed and it constant volume enery containment has increased with the sqaure. Together they from a 3rd power. as X time X squared is = X to the 3 rd power.

I hope this explains things

Wouter