Here's the final bilge wiring schematic with thanks to Ian, Brian, and
Larry:

http://home.maine.rr.com/rlma/BilgeCircuit.jpg

I'm going to try it without the snubbers. The relay sockets have
diodes designed for the relay coil suppression. Most bilge circuits
seem to get along fine without motor snubbers. The relay is listed
for either lights or horns up to 300 watts. Horns presumably would
have a big coil somewhere in the circuit for either a motor or an air
solenoid so the relay contacts ought to handle the flashback from the
bilge pump motors. The whole bilge circuit is connected to the
batteries instead of the bus so the batteries ought to soak up any
inductive surge. I'd appreciate being convinced otherwise though
because I always like to learn something.

The circuit also includes a manual override on just one pump. I
already have a bilge switch on my panel and this will give me a use
for it. Nothing will happen if it is activated while the waterlevel
is below the lower switch. If the waterleve is in between, a bump of
the bilge switch will pump it to the bottom just as if the top switch
had activated. Normal position for this switch will be off and I'll
have to leave a note to this effect for charterers or borrowers.
Leaving it on possibly could put the system into endless cycle mode
but, with just one pump line draining back, it is less likely. My
calculations make that prediction too close to call.

A side benefit of this whole rig is elimination of pump chirping with
water sloshing around in a sea way. Nothing will happen if the lower
switches are going up and down. If the water level gets high enough
for the upper switch to be sloshed on, the relay will trip and the
pump will run until the lower switch opens. As soon as the lower
switch opens, even momentarily, the pump will shut down. This will be
important with a bilge the shape of ours.

--

Roger Long




--

Roger Long

The link above now shows the system as installed. I had to give up on
the manual overide as it was more work than to tackle to break the
bilge switch out of the bus bar and reroute the bus around it. It was
lily gilding anyway because you can just pick up the high float
switches if you want to pump down before the system reaches normal
start level.

I also did install the snubbers after accidentally blowing out the
little diodes in the relay sockets by hooking up the test battery
backwards.

The system works great.

--

Roger Long