On Nov 24, 12:00*pm, Wayne.B wrote:
On Wed, 24 Nov 2010 07:20:17 -0800, Mark Borgerson





wrote:
That's a good point. *One reason for lock washers on high-grade bolts is
that they compress so you don't have to stretch the bolt.

Another reason for a lock washer is differences in thermal
expansion/contraction. * If you tighten a steel bolt against an aluminum
flange when both are hot, *the flange will contract at a different rate
than the bolt as it cools. * The aluminum will contract at almost
twice the linear rate of the steel bolt. *Conversely, tightening
the bolt when things are cool will increase the bolt tension when
both are hot as the aluminum expands more. * This is probably
a good thing----especially as it lets you work without burning
your hands! * ;-)

Balancing out all these factors is how mechanical engineers earn a
living. *The rest of us use LocTite! * (Note, LocTite may keep you
from losing the nut---it won't keep the belt tight in this application
if the thermal factors aren't accounted for.)

One thing that might help keep the belt tight is to use 60-grit
sandpaper across the adjustment arm on the side facing the aluminum
alternator flange. *WHen you tighten down the *bolt, the arm should
press some grooves into the aluminum to act as interlocking 'teeth'.

You should also be careful about overtorquing the bolt. *Depending
on the thread size, you could strip out the threads in the aluminum
flange.

Most of these issues are things you learn over the years as
you maintain your boat. *It sometimes helps to list the
issues just to make sure something isn't being overlooked.

Lots of good points there and thanks for the comments.

For now everything is about as good as it's going to get for a while.
We'll be putting some serious hours on the boat in January so I'll be
keeping an eye on everything (and carrying a spare alternator or two).

With three heavy duty belts in place I'm hoping that belt wear and
slip will not be an issue. *The old alternators were running fine on
two belts but they couldn't keep up with the electrical loads.- Hide quoted text -

- Show quoted text -

That will be a good test.

I am inclined to agree with some of the other posters about the amount
of electricity you seem to need. It would have been a lot simpler to
look for ways to reduce the power requirement rather than engineer a
solution to supply that much power. If you cook with propane then
what do you really need besides lights and power for the electronics?