On Tue, 20 Nov 2007 07:56:28 -0500, Martin Baxter
wrote:

Wayne.B wrote:

The other issue with single engine is wear and tear on the
freewheeling transmission.

Why let it freewheel, a freewheeling prop generates more drag than a
stationary one?

Cheers
Marty

That's true but it's not that easy to safely stop a 30 inch prop on a
2 1/2 inch shaft from free wheeling. This topic gets a fair amount of
discussion in the trawler groups. People have tried various jerry
rigged schemes like pipe wrenches and wrapped lines on the shaft tied
off to engine mounts but neither of those schemes holds much appeal
for me, and it is very advantageous to have the idle engine quickly
available for maneuvering. Everything's a trade off. There is no
disputing the fuel save however even though it may not be fully
optimal. We arrived in Florida at 5:00AM this morning after 2 1/2
days off shore. The fuel saved by running slow speed, single engine
was in the neighborhood of 150 gallons.

The other thing we've done that has saved significant amounts of fuel
is to install high output alternators on both engines, and couple them
to the house bank with battery combiners. The saving comes from
reduced generator run time since we can now use the inverter for
routine AC needs when underway without discharging the house bank. The
reduced generator time also lowers maintenance and replacement costs.