nimbusgb wrote in news:1181027399.917094.159070
@m36g2000hse.googlegroups.com:

Amps may be helpful when looking at an instantaneous situation. A
constant 5 amps into 13.8 volts would be enought to run the nav
instruments , radio and some of the load required for a fridge or
autopilot.

"Lionheart", an Amel Sharki 41 ketch, has a "shaft alternator" on her
freewheeling shaft. You must have a hydraulic transmission designed to
be free wheeled to use one, not just "leave it in neutral". The Perkins
transmission on the 4-108 is larger than most of them.

Her shaft turns, at 6 knots through the water, about 70-80 RPM. This
turns a big pulley made for a flat cogged belt. The pulley is about 12"
in diameter up near the back of the transmission. The belt drives a
special, slow-turning alternator, who, I'm guessing, is turning about 300
RPM at this speed. It's driving a 2KW Raymarine radar/color chart
plotter, Garmin 185 GPS/sonar, a string of B&G Network instruments,
including B&G Network Pilot electro-hydraulic autopilot, a Yeoman chart
table, a Dell Latitude w/HP Printer, a 12V fridge, bilge pump, water
pump, all the lights. Loaded down, the shaft speed drops, of course, but
she'll put out 15-18A at 14.2-14.4V to charge the 660AH golf cart beasts,
too.

As the Amel is already slower than dirt, a sturdy but leisurely cruiser,
I don't see any difference between on and off positions on the control
panel for the shaft alternator. Just pulling the 200 gallon water
tank....er, ah....6' fat keel...that's better...is draggin' her down to
make her comfortable. Noone is in a hurry on a Sharki...(c;

Larry
--
If electricity comes from electrons, does morality come from morons?