Roger Long wrote:
And:

If your boat is marginally powered, you could reduce the pitch so that
the engine will reach maximum RPM slightly before hull speed. This
will optimize it for lower speed you make in a headwind but you may
have to be careful about over speed depending on your governor set up.

You will only gain from this if blade area is sufficient. In most
sailboats, it is not. This also means that the engine will be running
at a slightly higher RPM for all boat speeds which means more noise
and wear.

If you have the engine power you need in headwinds, and the prop area
for maximum efficiency free running, optimizing the prop as I
described will still leave you with the bucking power you need in all
but the worst conditions. Very few people would want to lug the prop
necessary to deal with those forces around all the time unless it is
feathering. Very few sailboats will have been built with sufficient
prop clearance to install such a prop even if it is feathering. You
would have to plan for this at the design stage.

G'day, folks
I've just bought an H28 with an MD2B auxiliary. I haven't had a chance
to experiment yet but I'm looking for a starting point. I know there's
a bunch of people here with MD2B's in similar size boats, what do you
cruise at and what sort of consumption do you get at cruise?
Preliminary indication seems to be that 1600RPM in smooth water is
getting close to hull speed, so there seems to be a heap in reserve.
Interested in comments.
Thanks
JM