[C320-list] Bilge Pump Makers? Comments? Experiences?

[Stephen Cox]

My MkII came with it's bilge pump fitted in the bilge itself.  It ultimately
failed with a small wood chip from the build process jamming the impellor.
I subsequently installed a much larger Johnston pump.  

However, there was enough water collected in the bilge at one stage to
trigger the pumping process but not enough to really pump the bilge right
out. So with the back flow of what's left in the delivery tube the setup got
into a start stop repeat cycle.  Inevitably before I could fine tune the
shaft packing gland correctly, this repeat cycle happened while I was away
for some weeks.  The nett result was that the bearings in that Johnston pump
suffered somewhat from being continually run in a partially dry environment
and are now very noisy.  

I don't believe putting a check valve in is the answer as the ones supplied
with most pumps I have seen are just rubber flaps that will not seal
effectively over the longer term. At best they would just slow the cycling
process down, not eliminate it.  Any more substantial "proper" check valve
will impede the flow of water obtainable because of the pressure needed to
overcome the valve mechanism, hardly a desirable outcome if taking on
serious water.

I have now fitted a pump to the front bilge compartment of the same size as
that originally fitted but with automatic sensing involving the pump
spinning up briefly every little while and sensing the load.  If there is a
load it continues spinning until all the water has gone and the load
decreases.  Yes there is still a back flow but it is smaller.  It is still
possible to get just the right amount of water in the bilge to cause a cycle
pattern to occur but because of the sensing process this is at least
periodic rather than continuous.

I have also replaced the larger Johnston pump with a new one, fitted in the
rear bilge compartment, with a separate larger disposal hose to the rear of
the boat. This new one is set up with two float sensors and some latching
relays to cause a significant water level differential between pump on and
pump off.  So no cycling occurs unless there is a real need. i.e. continuous
ingress of water.  The sensors are set to only fire when the water level is
well above the trigger point for the smaller pump, so it is an emergency
rather than a day to day bilge pump.  An alarm also sounds when this pump
runs.  Both pumps are independently fused.  I have the disposal hose outlet
to the side of the rear step, spraying out over the ladder lid, to easily
see if it is pumping and how solidly.

Further refinements have been:

1. Purchase a second identical automatic sensing pump as a spare and I have
also kept the noisy larger pump as a spare..
2. Fit waterproof plugs and sockets to both pumps' electrical leads and
screw connections on the hoses.  This means if I have a pump problem at sea
I can quickly replace the pump.  Trying to make jury rig electrical
connections or get hose clips and hoses apart in a heavy sea is not a
realistic proposition in my opinion.
3. I have fitted a completely separate water level sensor at a fairly high
level to catch the situation when both pumps for whatever reason don't
appear to have worked.  This sensor drives another bilge alarm and two
independently fused relays connected to the two bilge pumps.  This covers
the situation where the normal sensors have failed and serious water is
coming in and will ensure that if one pump has also failed at least the
other one will be kicked off.

This all sounds a bit belts and braces but does bring peace of mind,
particularly if sailing single handed or with inexperienced passengers
rather than crew.

I don't think we will ever solve the cycling problem without being OK about
having some water in the bilges.  I try to keep mine dry as an easy way of
checking for water ingress.



Stephen Cox   
Tegwen #1141