[Public-List] Automatic bilge pumps

[Stephen Gwyn via Public-List]

Having an automatic bilge pump means there is a window, possibly
quite a long window, between the first indications of a problem
and when the floor boards float. The only time I've ever had
anything close to a real problem was when I didn't have the
automatic bilge pump switched on.

I have two electric bilge pumps, plus the manual.  I have a small
electric Johnson 450gph (or smaller) pump connected to a float
switch with a debris cover, something like the Rule-A-matic.
It's connected to quite a narrow hose, so that the back flow when
it turns off is minimized. I tried the field-effect type of automatic
switch but if they don't always turn off when the water level
drops.

I have a second pump, a Johnson 2200 (or maybe bigger) gph pump
connected to a much larger hose. Its switch is the "stay-on" kind
not the usual kind of bilge pump switch that is only on if you
are holding it.  If the water is up to the floor boards, it will
drain the bilge in less than a minute.

On my boat at least, a dry bilge is quixotic. There is a very
slow drip from the rudder stuffing box. When the engine is
running there are drips from the prop stuffing box. I'm not sure
where, but rain gets in when it rains. There's condensation. The
ice box drains into the bilge.  In summer, when it's dry the
bilge pump goes off once a week.  In winter, when it's very wet
it goes off 2-3 times a week.  When I'm cruising, the ice box
sets off the bilge pump every 6 hours or so.

What happens if there's a problem? If you're on the boat and
sailing, the noise of the bilge pump going off will alert you to
the problem before the floor boards start to float (which is
after the water is over the batteries).  So you won't flatten
your batteries, because you'll notice in minutes that there is a
problem. If you're motoring, you may or may not notice the noise
and the indicator light, but you won't flatten your batteries,
because you're draining them at 2.5A and charging them at 15A.

If the boat is sitting at the dock and you visit it only
occasionally, there is theoretically a size of leak that is slow
enough that it doesn't set the bilge pump while you are visiting,
but is fast enough to flatten the battery between
visits. However, more likely it will keep the water down until to
visit, hear the bilge pump and solve the problem.

I had one case where (ironically) the bilge pump outlet hose
disconnected itself from the not-really-a-thru-hull on the
starboard stern quarter. No water came in at the dock or on
starboard tack, but it did on port tack, setting off the bilge
pump. I heard it and sorted out the problem. Otherwise I wouldn't
have been aware of the problem until I got back to the dock when
the floor boards would have been floating.

But the worst case was the automatic bilge pump was switched off
for some reason and the head wasn't set to dry bowl.  I woke up
in the middle of the night and stepped down into wet. The floor
boards were just starting to float. The batteries were under
water and the terminals were busy disassociating the water into
hydrogen and oxygen. Half-awake, I threw the switch on the big
pump, which rapidly emptied the bilge. If I had had the small
pump set to automatic, the noise would have woken me up.  Even if
it hadn't woken me, I would have noticed it at breakfast and it
would have kept the water from getting over the batteries.

In the past, I've made bilge pump counters out of cheap
step-counters and relays, but they don't last. The commercially
available pump counters either glow in the dark, keeping you
awake at night and sucking electricity, or can't be reset to zero.

SG