Tackling the Bilge Pump

Tackling the Bilge Pump

Date: Tuesday, March 13, 2018. 1128Z
Location: 53.1631° N, 9.0760° W — Aughinish

Boats leak. Above the waterline, and sometimes below. An above-the-waterline leak isn’t a bad thing when the boat’s in the water, in that it won’t sink. But it does mean that stuff gets damp.

I’ve read countless online articles about how to keep a boat dry, and it’s not a trivial exercise. For the most part, with the boat on the hard, I’ve stored everything I possibly could in the warm and dry attic. But the bilge does fill with water, and it’s annoying. We have no shortage of rainwater in the west of Ireland, and it’s collecting in the boat, which makes painting the bilge and re-installing the engine that bit harder.

So, the first task was to install a bilge pump and an automatic switch. Drilling holes into the hull of a boat is a bad idea for a variety of reasons. Even if you don’t go through the hull, you can expose the wooden core to water and it will rot. Even allowing water to seep into the glass fibre underneath the gelcoat is bad. I’d looked at a number of possibilities from alu plates to stainless steel plates, but eventually 3D-printed a base which I then epoxied to the floor of the bilge. On this, I mounted both the pump and the switch. From the pump, the hose goes through a “non-return valve” which prevents the water from coming back into the bilge, either from a wave hitting the stern and flooding down the skin fitting, or just because the hose from the pump to the skin fitting is quite long. I’ve seen this issue on Nikea (which doesn’t yet have a non-return valve) where you turn on the pump and it completely drains the bilge. But when you turn off the pump, all the water that was still in the length of hose drain back into the bilge again.

The wires for both the pump and the switch will be wired to a junction block above the bilge in the engine compartment, but for now, they’re loosely tied together.

I have a 220 volt “shore power” cable from the house to the boat, which I use for light and heat. So, for the time being, I moved the starter battery (a bog-standard lead acid) from the garage where it has been on float-charge, to the boat. I also brought the float charger. I jury-rigged the bilge wiring directly to the battery, and tested that water in the bilge does indeed operate the switch and the pump. For now, the boat should be draining of rainwater. It’s been too cold to do any work on the boat for the last couple of weekends, so I haven’t actually checked my handiwork. It’s possible the bilge is a foot deep in rain water!

The next tasks are to paint the rest of the bilge under the engine mounts now that it’s no longer flooded in rainwater, and to try and identify some of the rainwater leaks. I need to find the remnants of that tin of bilge paint I put in the garage, so I can order some more, too.

A side project (and one which has little or nothing to do with getting the boat back into the water) involves adding an Arduino board in an IP65 case, to monitor boat humidity, temperature, and to log every time the bilge pump switches on. I’d like to use this data to track how much water is getting in there, and what the temperature/humidity looks like, over time. I should also probably add a note to the stern of the boat to warn people that the pump operates automatically, and it’s possible they could be sprayed by cold and wet bilge water!

Dermot Tynan's Picture

About Dermot Tynan

Part-time sailor, full-time procrastinator. Software Engineer, Writer, Film-maker. Interested in all things cloud, sailing, autonomous systems and robotic sailboats.

Galway, Ireland http://intothemystic.eu