On Tue, 24 Aug 2004 21:39:53 -0400, "Doug Dotson"
wrote:


"Glen "Wiley" Wilson" wrote in
message ...
On Mon, 23 Aug 2004 18:27:58 +0200, "Jan"
wrote:
Generally, alternators over 100 amps need double
belts to tranfer adequate horsepower. The Balmar regulator is a first
class piece of kit. I'm happy with my setup. That said, I don't
think that there is a huge difference between the top vendors. Ample
Power, for instance, is also highly regarded.

I've been running a 160A Ample Power alternator for several years
on a single belt with no problem. You do need to be careful about
belt tension though. I wish I had the clearance for a large frame unit
(2 belts), but can't do.

Doug
s/v Callista

Doug -

Interesting. If it works for you, it works for you. But to be clear
for the original poster, that is counter to Balmar's recommendation.
Ample Power prefers 2 belts as well for the 160 amp #4059 model,
though as you say, they tolerate a single belt config with frequent
maintenance. In any event, I stand by my recommendation to the
original poster. From your post, I suspect you agree on the principle,
even though circumstances forced you to go another way. Everything on
a boat is a compromise, isn't it?

For the original poster: Taking 160 amps as an example, you're looking
at a load of about 3 HP + friction losses, which is a *lot* of power
to transfer for a single belt. I imagine that heat dissipation is
also an issue. I'd also note that in practical terms, you don't
always need to allow for rated output, but rather for actual output.
Even 50% discharged, my tiny battery bank won't accept more than
about 65 amps, regardless of the alternator rating. But I still
change my belts often.

Cautionary tale, for whatever it's worth: A friend of mine went with
a single belt rig when he knew he really needed two. That may not
have had anything to do with what happened; no knowing after the fact.
In any event, the belt (a Gates Super HC with only a few engine hours)
seems to have delaminated under load like a retread tire. The outer
portion of the belt was still being driven round and round, but pieces
separated enough to flay the raw water input hose, cutting it almost
in two. Of course, the engine immediately overheated at a most
inopportune time. Not to mention the salt water spraying all over the
engine compartment. And the flooding. And the towing charge, which
could easily have become a salvage claim. By the time they got him
close to home, a gale was blowing and the towboat refused to try to
put him in a slip. So he anchored outside the marina, but didn't have
an engine to set the hook properly. He started dragging about
midnight and wound up about 10 feet from the rocks. He stayed up all
night watching, but there really wasn't much he could do. He still
uses a single belt, but he buys the best industrial belts he can find,
inspects them before every engine start, and changes them at the
first hint of wear or whenever he gets nervous.

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