Bilge pump wiring




Do you recon this is Ok for this type of boat and usage?

I've got a 22ft centre console that I'm doing a tidy up on.

It mainly sits under cover on the trailer but sometimes on a mooring or at anchor at Rottnest.

The only times I've had water in the bilge is when there has been a lot of water on the deck from thunderstorms

or the bung has been left out , fortunately it can also be screwed up from the inside as well.

The pump has its own inbuilt float switch and is pretty quiet so it's not immediatlely 

obvious that it's going.

I thought if I wire the pump in parallel with a truck reversing beeper I can't miss that it's going.

Because it sits under cover on the trailer I don't want the pump wired to the hot side of the battery

all the time and I don't want it on a switch because they can be left off or on inadvertently.

I thought if connected to the battery switch It can't be left on of off inadvertently.

The boat has one battery one motor and one house circuit so I bought a

4 position battery switch and connected

The hot positive to 2

motor and house loads to 1

bilge pump to common

this way when the switch is on

Off - nothing is powered

1 - nothing is powered

2 - only the bilge pump is powered

1+2 - everything is powered

My logic is if the boat is running the pump can only be on,

but can be left on when the boat is on anchor by putting the battery switch on 2.

I put a circuit breaker to protect the wireing and a bullet connector in the positive to the bilge pump so it can be disconnected if needed,

and a momentary switch on the manual wire so I can turn it on manually to mop up

a small amount of water  that isn't enough to trigger the float switch.

The beeper goes whether the pump is going on auto or manual.

So far no flames or water.


Image Upload: 

scotto's picture

Posts: 2248

Date Joined: 21/04/08

I think

Wed, 2019-10-09 17:21

You've over complicated it.  too much shit to go wrong there IMO.  

generally, the tried and tested way is:

1). Run both batteries to a selector switch or VSR

2). run power from selector's common +ve to switching panel

3). wire bilge pump to switch panel. 

Float switched bilge pump. Leave batteries off and bungs out at home, leave batteries on when moored. If your boat takes on more water than a bulge pump can discharge, you've got bigger problems.

ensure boat is insured.  

Posts: 20

Date Joined: 06/10/13

 Thanks ScottoThere is only

Wed, 2019-10-09 17:42

 Thanks Scotto

There is only one battery and it is a float switched pump.

Didn't want to leave power on when moored as I've had kids fiddle 

with the tilt/trim and could cause injuries and other issues with live

electrics and an unattended boat

There is no wire to any switch panel,

its all in the rear locker and automatically on if the boats going or

off if the battery is turned off but I agree that it did seem more comlicated than

I thought it would be mainly because I didn't want a switch anywhere that

could be left the wrong way

scotto's picture

Posts: 2248

Date Joined: 21/04/08

My switching panel

Wed, 2019-10-09 18:16

my switching panel Has red lights when something is left on, so it's very easy to see.


you said you had both starting and house batteries? That's 2 batteries! You could just hard wired the bilge pump straight to one of the batteries, with an isolator switch  


I suppose it's just a matter of being vigilant with kids and passengers. NO ONE is allowed to tamper with my boat! Plus I triple check everything when I leave the boat moored, and I'm last to leave the boat.  

I'm not having a go mate. The work you've done is an awesome job btw. 


Posts: 20

Date Joined: 06/10/13

 I often anchor on the beach

Wed, 2019-10-09 18:28

 I often anchor on the beach at Rotto and several times

have found wine glasses and beer cans left behind.

Interestingly often with coins that have fallen out of their pockets

as they've climbed over the side

Posts: 451

Date Joined: 19/06/14

Hard wire direct to one battery

Wed, 2019-10-09 20:36

Chuck in a fuse . If it needs to work it will work if it doesn't need to work it won't .
Like Scotto said if it drains a battery it's the least of your problems ! 
Nice clean work by the way .


 My wife understands why I clean my rods n reels in the shower....


Posts: 20

Date Joined: 06/10/13

A four position battery

Wed, 2019-10-09 21:54

A four position battery switch is mostly used with 2 batteries but

In the first post The boat has one battery one motor and one house circuit

then in the 3rd post There is only one battery

I am using a 4 position battery switch but not two batteries

The logic was  not possible to have the pump accidenly turned off when the boat running

                     not possible to have the pump on when the battery switch off

                     is possible to have only the pump and nothing else on in one position 

                     able to manually activate it if needed with the momentary switch but not leave it on

                     able to manually disconect with the bullet connector if needed

                     unlikely to be unaware of it pumping because of the fecking beeping

Its a bit wierd connecting the pump to the terminal marked common and the engine and house loads to the terminal marked 1, but it works

The folk with the big boats seem to have a pump hotwired to a battery, do most of the trailer boats with only one battery too?


Posts: 432

Date Joined: 23/04/14

Not the right way

Wed, 2019-10-09 22:59

 A bilge pump is a protective device; it’s there for when other components have failed.

Correct and safest way is to have the bilge pump hard wired to the battery positive.  That way it can’t be accidentally switched off.  You can still turn all the other electrics off when the boat is unattended.




carnarvonite's picture

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Date Joined: 24/07/07


Thu, 2019-10-10 06:58

 Resurgence has it spot on. Pump is hard wired but if you don't like this then put another float switch in connected to an alarm set to go off before the bilge pump activates

sea-kem's picture

Posts: 11895

Date Joined: 30/11/09

 Exactly it's a necessity not

Thu, 2019-10-10 21:56

 Exactly it's a necessity not an accessory. Specially in my boat where you can't bail out below deck. 


Love the West!

scubafish's picture

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Date Joined: 15/08/12


Sat, 2019-10-12 07:57