Our OEM Rule-A-Matic bilge pump switch stopped working, and the failure was traced to a parted supply wire close to the switch. As this portion of wire is constantly submerged in bilge water, failure can be expected. The redesigned Rule-A-Matic bilge pump switch model 35A moves the wire exit to the top of the switch, out of bilge water. The new switch, however, is about ¾” longer than the original, and no longer fit in our 320 (hull #828).

This unfortunate situation allowed me to make a modification suggested by Chris Burti on the C320 list.  Rather than installing the mechanical Rule switch in the bilge, an electronic switch was installed.  These have no moving parts and are reported to be more reliable.  The West Marine Bilge Pro Water-Sensing Switch #7865637 fits neatly against the port side of the bilge.  It has four mounts; two on the base served as pilot holes for SS screws, the two on the outboard side were epoxied to the side of the bilge using Flex Set.  The Rule-A-Matic bilge pump switch was then mounted ABOVE the bilge by Flex Setting a small block of marine plywood to the hull, with the Rule switch screwed to it.  It was wired into the same circuit as the electronic switch.  This redundancy provides a backup should the electronic bilge pump switch fail and the water rises towards the floorboards.


Chris Burti describes the bilge as “the environmental equivalent of a urinal” so careful attention needs to be paid to wiring.  Heat-shrink Ancor connectors were used covered with heat shrink.

The last line of defense involves slipping a ¾” hose over the collection of wires, suspending it above the bilge water and pumping it full of silicone caulk.  Remember to have your hose and shrink wrap over your wires BEFORE you crimp your connectors!  If you don’t have a crimper, Practical Sailor suggests the Klein 1005.  It works very well.



Finally, Spiral Wrap (Calterm #73453 from Home Depot) was used to contain the wires and provide abrasion resistance.

Credit goes to Chris Burti for the idea of two switches.


Chris Willems

Chrysalis #828