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max-on 05-23-2008 11:42 AM

Pump Float and Three-Way Switch Install
My current setup is the bilge pump is turned on/off at the breaker at the nav station and I want to install an automatic sensor switch near the pump and a three-way manual/off/auto switch at the nav station (the boat does not get much water from the mast, but I have been concerned with not have an active bilge pump when I leave the boat), what type/size of wire should I use for the connections. Should I get the wire/connectors at west marine or can I get them at the hardware store? Is there a difference? As the pump is original to the boat 12 yr, when/should a pump be replaced, the pump get no use?

You know what, thinking about it now, I check that the pump goes 'on' but I have never tested its suction! :eek: Same for the manual pump!

TrueBlue 05-23-2008 11:56 AM

So, basically you do not have a float switch that activates the bilge pump and the only way to evacuate water is manually, via an on/off switch.

If the pump works and when testing, water is seen being ejected from the through hull, then there is no need to replace the pump. Take a trip to your favorite marine supply store and pick up a coil of marine grade wire - which should be stranded copper - tinned throughout, not just at the ends.

Also pick up a Rule float switch, either with Mercury or the newer mechanical type, along with a three-position switch. There is a wiring schematic provided with the Rule switch, which shows several ways of wiring the switches.

It's a very easy and quick project to do, if you have all the materials collected before doing the job. Make sure you use marine grade wire connectors and shrink-tubing.

sailingdog 05-23-2008 12:07 PM


You should probably setup one bilge pump that is hard-wired to the batteries with a float switch of some sort. Having a switch for this might not be a bad idea either. :) This way, you don't have to leave the master DC switch on when you leave the boat. If you don't do this... the chance that you'll accidentally leave the VHF radio or some thing else on that will drain the batteries is pretty high.

If you do install a bilge pump that is hard wired to the batteries (with a fuse in-line of course)—you should have a bilge pump counter attached to it. By noting the number on the bilge pump counter, you can see if the pump is cycling more often than usual or not.

Get the connectors and switches from West Marine, since you really want marine grade for this purpose. As for switches, I prefer manual bilge pumps with separate dedicated bilge switches... the electronic bilge switches can be more reliable than the mechanical ones.

BTW, you might want to put an oil trap on the output line for this bilge pump if it is your "maintenance" level pump and you have any oil in your bilge, so you aren't fined for oil discharge via your bilge pump.

If you want help with a wiring diagram for this, let me know. :)


TrueBlue 05-23-2008 12:21 PM

This is the float switch max - in case you are unfamiliar with them:

Most of the boats I have owned have had high-low switches installed in the bilges - purchase a pair if you'd like this arrangement. Again, very clear wiring schematics are provided with the switches - covering many different arrangement options.

max-on 05-23-2008 12:41 PM

I was thinking about this kind of electronic switch:

and this kind of three-way switch:

SD, I like your idea of a direct connection to the battery so I would not need to leave on the main.

sailingdog 05-23-2008 12:49 PM

Probably a good idea... I've seen two boats sink because they had an automatic bilge pump on the main DC panel, and they left the something on... and killed the batteries... In one case it was cabin lights, the other it was the VHF.

TrueBlue 05-23-2008 12:52 PM

I've always stored my boats at a marina slip with shore power. Keeping your boat full-time on a mooring, raises a higher level of concern for these power drain risks.

sailingdog 05-23-2008 01:06 PM


One of the two boats was at a dock with shore power... but the storm that caused the boat to have bilge water problems also knocked out the power to the marina. :) Better to be safe than sorry.

TrueBlue 05-23-2008 01:13 PM

Actually, my second to last boat's bilge pump was wired directly with no switch override. It's a smart thing for boat builders to do and thought it was a standard on all boats.

That is, until discovering that my Nauticat was wired with a three way toggle switch, not unlike the one max posted. Could not see any value in having an off position - especially in conjunction with a float or electronic sensor switch.

max-on 05-23-2008 01:18 PM

Keep in mind SD the size of my boat, the relatively flat shallow bilge, and that I have yet had a need to use the pump. The bilge area is so shallow that I think water would need to be at the floor before the pump went on, thus, why I have not 'tested' the pump.

The only seacock I leave open is the raw water on the engine from the saildrive, given I have to remove the stairs and cover to access that; an access port is another project.

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