[C320-list] Strange "thunk" electrical noise

[Bill Culbertson]

Dave - that's a great suggestion.  I do keep thru-hulls closed all winter after winterizing (I know there are proponents of leaving open).  All breakers are off so in theory no current should get to that pump on a battery switch state change.  But I like your idea just the same.  I suppose I can toggle the thru-hull next time to see if symptoms change at all.

 -bill


----- Original Message ----
From: Dave Moores <dmoores at cogeco.ca>
To: C320-List <c320-list at catalina320.com>
Sent: Friday, December 28, 2007 2:38:26 PM
Subject: Re: [C320-list] Strange "thunk" electrical noise

Bruce - here's another guess that sounds like it might be correct.  I have
relevant experience, maybe...

If you forget to open the thru-hull that the pump that drains the shower
sump uses, the pump stalls under back pressure.  Could it be that when you
turn it back on all the pump can manage is a single stroke before it stalls
again.  That would be your thunk.  It does sound like that. Or maybe the
pump is just defective in some other way causing it to just do one stroke.
Just another possibility.  Let us know if you ever find out!

Dave Moores

California Girl #342

-----Original Message-----
From: c320-list-bounces at catalina320.com
[mailto:c320-list-bounces at catalina320.com] On Behalf Of Bruce Heyman
Sent: December 28, 2007 1:05 PM
To: 'C320-List'
Subject: Re: [C320-list] Strange "thunk" electrical noise


Bill,
Strange indeed!  Did the "thunk" sound like a solenoid?  That said the only
solenoids I'm aware of are for the starter, propane and I'm not sure but I
wonder if there is one for the windlass. 
Bruce
Somerset #671 SoCal

-----Original Message-----
From: c320-list-bounces at catalina320.com
[mailto:c320-list-bounces at catalina320.com] On Behalf Of Bill Culbertson
Sent: Thursday, December 27, 2007 4:53 PM
To: C320-List
Subject: [C320-list] Strange "thunk" electrical noise

I finally made the drive down to the marina yesterday to check on Harmony.
We'd had a big rain a week back which melted all of the snow and yesterday
was about 40dF and sunny so it was quite pleasant.  All was well aboard and
it was comfy under her winter cover.  The batteries didn't need as much
charging as they usually do.

Then as I was closing up shop I shut off the main battery switch and
remembered something so turned it back on.  There was a distinct "thunk"
sound.  Strange.  I repeated off, on and each time there was a thunk.
Location was ambigous but seemed starboard about deck height.  I have a
Link20 monitor so after I turned off all cabin lights and everything else
electrical, I could confirm that there was nothing drawing any current.   In
that state, I could switch it off and on without the thunk.  But turn on one
cabin light and repeat and "thunk".  Again via Link20 I confirmed that only
one cabin light's worth of curren was flowing when I turned the switch on
and heard the thunk.  To be certain, I toggled the windless breaker by the
battery switch (Harmony is #859 and has the switch on the starboard panel)
to be certain it was disengaged.  

I also pulled the starboard cushions and boards to better localize the sound
and to inspect everything in that area.  The sound is not from the settee
area and I saw nothing unusual down there.

This baffles me and worries me.  I didn't smell anything.  I stuck around
for quite a while after disengaging everything to see if there was any
electrical smell or anything to raise more fire worry.  

Anyone have ideas?

-bill



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