Multiple Bilge pumps wiring setup

**Aaronhl** · 04-21-2021, 06:55 PM

So I took out all the soggy foam in the bottom of my tunnel V so now I have the two outside sponsons and the middle that I would like to keep dry. The 3 areas are closed off from one another and I have a removeable plug for each of them...I was planning on having 3 separate outlet holes on the side of the boat also...I was wondering if you guys had any good ideas on how to wire 3 pumps, should I run 3 individual switches or one switch to control all three at the same time since they appear to be able to be run dry...Id rather not have to wire float switches and may end up getting auto units if you think that matters...Any tips would be helpful so how do you guys have yours wired, what am I missing

**Whaaaaat** · 04-21-2021, 07:09 PM

Auto units are battery killers in my experience. Quality float switches are the way to go. I can't remember who makes it but there's a compact water sensor I've used before that seems to last as long as modern float switches. If it were my boat I'd have 3 switches and 3 indicator lights.

**Aaronhl** · 04-21-2021, 07:31 PM

Good to know about the auto units, I don't plan to keep the boat in the water for days so I dont think I really need auto units for now, maybe I will use 3 separate switches like you said and then move to the floats later on if needed...the outside sponsors barely have a level floor, I will have to make a bracket for the pumps so they can stand upright

**4Speed** · 04-22-2021, 05:35 AM

My STV Euro has 3 pumps; one in the center pod and 1 in each sponson, they are all on 1 on/off switch located in the dash with no float switchs. I rarely leave it in the water over night but I am thinking of separating 1 and placing it on a float switch with a auto/off/on switch - just in case.

**rock** · 04-22-2021, 06:20 AM

Be careful with the float switches. I refuse to use them due to a near disaster. 22' bullet with an 300xs on Kentucky Lake. Boat broke down so we removed it from lake and a local marina was going to loan us tools to disassemble lower unit as it had a (unknown to us at the time) broken pinion. While we were sitting at a picnic table at the cabin with the boat next to us I noticed some smoke coming from boat. We scrambled to disco the batteries. Turned out the float switch was gunked up from crap in the bilge and mounted under a plastic fuel tank that was full of gas. Could have happened while on water or while being towed down the road. We got lucky.

Rock

**Whaaaaat** · 04-22-2021, 06:26 AM

At least have the center on a float switch, doesn't take overnight to sink. A small leak while your on the sandbar with a frosty beverage might go unnoticed until it's too late, float switch will handle that.

My reasoning behind the 3 separate switches is circuit redundancy. With only one switch, one bad pump will kill the circuit, and the other 2 pumps. I try to keep fuses as close to the source as possible. Fuse then switch then load. If you only want one switch then, it would be. Main fuse, sized to handle 3 pumps, then switch then 3 individual fuses, sized to run 1 pump, to there dedicated pumps, this way a bad pump can't kill the other 2.

**Whaaaaat** · 04-22-2021, 06:29 AM

Originally Posted by rock

Be careful with the float switches. I refuse to use them due to a near disaster. 22' bullet with an 300xs on Kentucky Lake. Boat broke down so we removed it from lake and a local marina was going to loan us tools to disassemble lower unit as it had a (unknown to us at the time) broken pinion. While we were sitting at a picnic table at the cabin with the boat next to us I noticed some smoke coming from boat. We scrambled to disco the batteries. Turned out the float switch was gunked up from crap in the bilge and mounted under a plastic fuel tank that was full of gas. Could have happened while on water or while being towed down the road. We got lucky.

Rock

What let the smoke out? The switch or the pump it left stuck on?

**Whaaaaat** · 04-22-2021, 06:35 AM

Rock brings a good point. With only 1 switch, if there is say a small leak in 1 sponsor, you'll have 2 pumps running dry continuously while only needing one. They might be rated to run dry but I doubt the rating is continuous. 3 complete separate circuits allows you to only run the pump you need.

**rock** · 04-22-2021, 06:47 AM

I have kept this around so when people ask me to install one I can show them why I won't. Switch melted, not the pump. These things get mounted in the dirtiest part of the boat and everything that gets lost in the boat ends up in the bilge. Don't take much to stick one. Remember this was under 30 gallons of fuel in a plastic tank. Would not have been pretty.

Rock

**Whaaaaat** · 04-22-2021, 07:11 AM

Definatly some compounding issues there. I was never a fan of that cage style. I like the open arm you can test easier and visually check that there free of obstructions. I test them at least a few times a year and always before any long trips. I'm happy if they lasts 2 years, I don't expect much more out of them than that. Once they took the mercury out of them.....

My allison has a pump and float switch. I don't think it's been on other than testing the whole time ive owned it. I still like knowing it's there.

Dive boat, 2 pumps 2 floats and 2 switches. I wouldn't leave the dock without all of the above working. Again there tested often and replaced at the slightest sign of failure.

Another tip, when you wire pumps and switches leave a generous service loop. 1. It allows you to keep the electrical connection as high in the bilge as possible. 2. Pumps and switches fail, count on it. Allow enough excess wire to change each 3 or 4 times before you need to pull new from the switch.

**DangerNewb** · 04-22-2021, 07:59 AM

My young son many years ago flipped the pump switch on a fishing boat and it ran for at least a day or two before I noticed it. Boat was in the garage. the Rule pump still worked 10 years later.

**flabum1017** · 04-22-2021, 05:31 PM

Originally Posted by rock

I have kept this around so when people ask me to install one I can show them why I won't. Switch melted, not the pump. These things get mounted in the dirtiest part of the boat and everything that gets lost in the boat ends up in the bilge. Don't take much to stick one. Remember this was under 30 gallons of fuel in a plastic tank. Would not have been pretty.

Rock

In my 35 years as a marine mechanic, I have never seen a float switch burn up like that. I would assume the cause of that was water wicked into the switch wires and corroded the wires where they are soldered onto the mercury switch.... created a bad connection and it overheated and smoked.....

I have seen bilge pumps bubble up their plastic housings from being jammed and have seen corroded wire connections burn up.

90% of the times I see a burnt up component, it's due to water intrusion/corrosion......

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**Chaz** · 04-22-2021, 07:49 PM

I gotz two pumps in my boat on a single rocker switch . Center off / up is on / down goes through float switch's. When the monsoon starts it's easy to duck into a marina / tiki restaurant .. put em on the floats , order an Ice-tea and a Mahi sammich . Watch the drunk girls dance with each other . If it quits rainin before I'm done eatin .. they shut themselves off . If it's still rainin when I'm done .. Excuse me Miss .. may I have another Ice tea .. please ...

**keefallan** · 04-25-2021, 01:46 PM

Bottom line is there is no right way to do it.......1 switch......2 switches......3 switches.....Just make sure you wire it properly(sealed connections, fuses, good wire, etc) and know what pros and cons your set-up will have......then do routine maintenance to make sure its working....

**tnelsmn** · 04-25-2021, 09:54 PM

Originally Posted by Whaaaaat

1. It allows you to keep the electrical connection as high in the bilge as possible. 2. Pumps and switches fail, count on it. Allow enough excess wire to change each 3 or 4 times before you need to pull new from the switch.

This is why I put a weather pac style plug in for the bilge pump. When the pump fails I just have to crimp on one side of the connectors and reuse the pump side of the plug. Then just plug it into the boat side of the plug that never has to change.

P.S. mine is wired with the auto to a separate switch, not directly to the battery.