Larry wrote:
Saw a 380A 24V, gear-driven alternator for a big bus at the electric
shop while buying my Chevy stepvan a new
starter..........DROOL....(c;

It had oil passages the big diesel pumped engine oil through the core
of it to cool it!

That'll recharge that big Heart Inverter battery.....quick!

To answer your question, alternators are very efficient. The only
problem I'd see with a huge alternator is the weight of the unit
making the engine lean to one side and mis-aligning the shaft, which
would be BAD.....and the flywheel effect of a larger armature
starting and stopping and changing engine speeds. I'd be afraid of
the weight/alignment issue in a small sailboat engine bending the
mountings over to one side. I suppose you COULD mount the alternator
off the motor but then the pull on the belt a big alternator would
pull would pull the engine to that side all the time, probably
ruining the engine mounts. My friend Geoff had that trouble with his
Yanmar 3GM and a huge car air conditioner compressor that used R-12
to run the fridge's big cold plate. You could SEE the engine pull
towards the externally-mounted compressor.....That's got to hurt
shaft bearings.

I am avoiding side load all together. Welded up a frame in heavy 6x2
channel that bolts tothe stringers in front of the engine with a short
1.5" diameter shaft on double 1.5" pillow blocks. The Niehoff and Cat
watermaker pump mount on the bracket with all the V-belts and pulleys on
the shaft. It is connected to the damper plate with an Aquadrive.
(Basicaly a very short CV joint) The engine can wobble all it wants
without any side load.

I am still a little worried about the total horsepower coming off the
front though. I am figuring I will need about 9HP with the alternator
and the pump running flat out. The Yanmar installation manual does not
give limits for this kind of mount. It is more concerned with side load
on directly attatched drive pulleys.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com