"Dave" skrev i en meddelelse
...
On Mon, 06 Jun 2005 19:31:31 GMT, "Roger Long"
said:

When
the prop is freewheeling, it is producing energy

A fairly basic principle: energy can be neither created
nor destroyed.

Isn't it right, that when the boat is sailing (just for sail
that is) you need some energy to keep the propeller from
turning - i.e. to keep it fixed - and that gives a certain
drag on the boat ....

My intuition tells me that when you ' loosen the grip' on
the propeller shaft and let the propeller turn freely, it
reduces the drag on the boat. Right or wrong?

--
Flemming Torp