[qume]

No I don't, my calculations at this stage are as follows:

Sail area - same as my 10 ton boat. Gets me to 7kts in a good strong wind.

Boat they intend to install it on: 110000 tons!

My point is that for this to have any impact at all, a massive amount of energy has to be extracted from the wind. An amount of energy that just doesn't exist in the volume of moving air they are talking about.

I'm still baffled by this.

[llukas]

This is more complicated - you ignore hull speed for one. Amount of force needed to move ship through waves is non linear: https://en.wikipedia.org/wiki/Hull_speed