Re: Why does he have to pedal???

--"Wilbur Hubbard" <wilburhubbard@[EMAIL PROTECTED]
> wrote in message 
news:47e1495e$0$47196$892e0abb@[EMAIL PROTECTED]
> If it were 95% efficient it would go backwards at 5% of the wind speed.
If 
> it were 50% efficient (which is probably realistic) it would go
backwards 
> at 50% of the wind speed.
>
> You can't get something for nothing.
>
> Wilbur Hubbard

Surely that ignores the relative resistance (viscosity/density) of air and

water. Otherwise what you say would imply that the windage arising from a 
5kts breeze on a boat at anchor would be equal to a 5kt tide, which
clearly 
it is not.
Taking your 50% example, are you saying that in a 10kt breeze the craft in

question would go backwards at 5kts?
I don't think so Wilma.