"Roger Long" wrote in
:

But, that doesn't explain why it works exactly as intended when
manipulated by hand.

What you've hooked up is a "latching relay". Once the high switch is just
momentarily activated, even for a few milliseconds, the power it provides
closes the relay contacts, which THEN provide the power to keep the power
flowing in the absense of contact in the high switch. It "latches" to ON
and will stay on as long as the low switch is closed. If the low switch
opens just momentarily (the boat rolls?), the relay drops out and now there
is no power to the low switch because the high switch is open so the relay
cannot be re-energized until the high switch turns on. This circuit would
be great if you only wanted the bilge pump to run after the water got "so
high" (where the high switch activates), but kept the bilge pump running to
dry the bilge to the point the low switch opened...(c;

Just move the wire powering the low switch from the side the schematic
shows on the high switch to the other side of the high switch and your
problem is solved....no more latching and lockout.

Beautiful drawing, by the way. What I'd expect from such a fine marine
architect.

--
Larry

You know you've had a rough night when you wake up and your outlined in
chalk.