On Sun, 25 Nov 2007 07:20:49 -0500, "Roger Long"
wrote:

It simply has to take more horsepower so push a twin screw boat with a
single engine than with both. One prop is dragging and whether it is fixed
or freewheeling, it is going to increase the overall resistance. The thrust

Snipped

money?

A mechanic I talked to recently told me that he sees a significant
difference in interior condition and time between overhauls on sailboats
that live on moorings or have engine driven refrigeration compressors
because owners of those boats tend to idle for long periods to charge and
cool.

You are confirming my own experiences regarding running on one engine
to save fuel is something I have never been able to achieve. Assuming
normally sized engines.

And, I'm sure that essentially running a diesel engine at idle
continuously is probably bad for it but I have never been able to
detect the, so called, glazing of the cylinder walls that is a
supposed result. Every diesel engine I have taken apart had cylinder
walls that looked exactly the same as any other engine, a slick
polished surface.

But anyway, Thank you for the comprehensive comments.

Bruce-in-Bangkok
(Note:remove underscores
from address for reply)