Bilge pump: automatic or non-automatic?

[BelleSerene]

I need to replace the Noble Sloop's bilge pump. It's a non-automatic one with an external electronic water sensor in place of a mechanical float switch. It's wired so it constantly detects water and if it finds any, it'll switch on. There's also a switch on my panel so I can over-ride the water sensor and force it on.

I would replace this with a Rule pump with a Water Witch sensor strapped to it.

It seems the new thing to do is to use an 'automatic' bilge pump that turns itself on every few minutes to detect water: [ https://www.marinesuperstore.com/marine-pumps/bilge/rule-automatic-bilge-pump ]. Clearly, for safety this should be wired permanently to +12V, making my bilge pump switch redundant.

Any experienced views on which way to go?

 

[pvb]

I've never had an automatic bilge pump on any of my boats, but my current boat, being newish, has an electric pump which requires switching on manually. I guess it all depends on how much water there is in your bilges. My bilges only contain dust and fluff. If you have a persistent leak, you need to decide whether the likelihood of it getting worse is significant, and then decide whether your proposed automatic pump could cope with the possible inflow of water. Most pumps perform rather less well than their quoted performance figures might suggest.

 

[Sailingsaves]

I suspect you have plenty of electricity to spare. That's good for the pumps that turn on for a second or two regularly. No impeller to damage (just plastic vanes).

My concern with this is that it still places wear on bearings etc. If it becomes blocked, it won't work (but that will apply to option two).

2) Pump with electronic switch. No wear and tear. Only turns on if water is detected. (Would still need a strum box).

I have both types (although I made the switch myself for a few quid instead of £36 - £40).

Neither has given a problem, but I don't have lots of electricity so I use the electronic switch one for now.

I will use both (I love built in redundancy) when I have enough electricity. Only time will tell if the 'automatic' one suffers wear and tear.

 

[PaulRainbow]

I need to replace the Noble Sloop's bilge pump. It's a non-automatic one with an external electronic water sensor in place of a mechanical float switch. It's wired so it constantly detects water and if it finds any, it'll switch on. There's also a switch on my panel so I can over-ride the water sensor and force it on. <snip>

That's what i have and i'd stick with it.

 

[Sailingsaves]

I've never had an automatic bilge pump on any of my boats, but my current boat, being newish, has an electric pump which requires switching on manually. I guess it all depends on how much water there is in your bilges. My bilges only contain dust and fluff. If you have a persistent leak, you need to decide whether the likelihood of it getting worse is significant, and then decide whether your proposed automatic pump could cope with the possible inflow of water. Most pumps perform rather less well than their quoted performance figures might suggest.

I once delivered an extremely expensive boat and it took on a lot of water that made its way to the bilge via a lazerette that was not properly closed (catch was broken). An alarm went off.

An automatic pump would have dealt with it. Cheap piece of safety equipment. Even the smallest Rule pump is better than my hand pump.

 

[Sailingsaves]

That's what i have and i'd stick with it.

They said they need to replace it for some reason.

 

[pvb]

I once delivered an extremely expensive boat and it took on a lot of water that made its way to the bilge via a lazerette that was not properly closed (catch was broken). An alarm went off.

An automatic pump would have dealt with it. Cheap piece of safety equipment. Even the smallest Rule pump is better than my hand pump.

I'm afraid I have to disagree with your description "safety equipment". Most automatic bilge pumps have very limited pumping ability - OK, they'd perhaps cope with the leaky lazarette you mentioned, but that's hardly a life-threatening problem.

 

[Sailingsaves]

How about stove in wash boards? Ripped off fore-hatch?

Now we all know from your post about the amp meter that you don't like electronic stuff (except for your bow thruster and AIS etc), but you can disagree. I carry pumps. Not to mention if one hits something (remember that silly film with that actor that never talked?)

Oh, and my 2700 Rule pump is so powerful it could almost work as a bow thruster if stuck on a stick and held be crew.

 

[pvb]

How about stove in wash boards? Ripped off fore-hatch?

Now we all know from your post about the amp meter that you don't like electronic stuff (except for your bow thruster and AIS etc), but you can disagree. I carry pumps. Not to mention if one hits something (remember that silly film with that actor that never talked?)

No idea about the film you mention, but the average automatic bilge pump won't achieve much in difficult circumstances. As for your ammeter jibe, I love electronic stuff, as long as it's practically useful.

 

[Sailingsaves]

No idea about the film you mention, but the average automatic bilge pump won't achieve much in difficult circumstances. As for your ammeter jibe, I love electronic stuff, as long as it's practically useful.

Practically useful is an opinion.

A 2700 pump can be measured quantitatively dependent upon all sort of factors such as hole size in hull and depth of hole. So it is not an opinion.

If boat is 'unsinkable' a bilge pump is a safety device in that it stops one sitting in a wet boat and succumbing to hypothermia.

If on a swinging mooring and log or something holes you whilst asleep...

Anyway, with my two electric bilge pumps and 3 handhelds and a bucket I feel safer than not having them. I don't have a bow thruster, electric windlass, etc (that in my opinion are luxuries whereas a bilge pump is a safety item).

Some of my sailing was on fishing smacks with no engine. They did have an anchor and bilge pump. No winches of any kind, no cooker etc. No electricity, no depth sounder; lead line.

 

[pvb]

Practically useful is an opinion.

A 2700 pump can be measured quantitatively dependent upon all sort of factors such as hole size in hull and depth of hole. So it is not an opinion.

If on a swinging mooring and log or something holes you whilst asleep...

Anyway, with my two electric bilge pumps and 3 handhelds and a bucket I feel safer than not having them. I don't have a bow thruster, electric windlass, etc (that in my opinion are luxuries whereas a bilge pump is a safety item).

Some of my sailing was on fishing smacks with no engine. They did have an anchor and bilge pump. No winches of any kind, no cooker etc.

Electric bilge pumps are rated usually at zero head and (often) 14v supply. In the real world, with discharge head, outlet pipe friction losses and lower voltage, their performance can be disappointly low.

With decent regular maintenance, I'm not sure how a "log or something" might suddenly cause a substantial leak. But if you sleep soundly with your 5 bilge pumps, that's fine.

 

[Yngmar]

The Rule automatic bilge pump is fully computerised. The pump will check for water every 2.5 minutes, if it detects water then it will pump until the water has been removed at which point it will revert to the sense mode. This pump means there is no need for external float switches.

Wow, that'd be really annoying and disruptive to my sleep, not to mention pointlessly suck battery power. Also the pump, which on our boat has never seen water except the one time we tested it with the hose would spend all this time running dry. Your current setup with the sensor and override switch sounds a lot better to me.

 

[Sailingsaves]

Electric bilge pumps are rated usually at zero head and (often) 14v supply. In the real world, with discharge head, outlet pipe friction losses and lower voltage, their performance can be disappointly low.

With decent regular maintenance, I'm not sure how a "log or something" might suddenly cause a substantial leak. But if you sleep soundly with your 5 bilge pumps, that's fine.

Well, I have tested the 500 and 2700 rule bilge pumps and they pump admirably from 3 metres down and on pretty poor batteries; pump impressively so actually.

EDIT owing to lw395 comment on page 3, post #24 : It is the 3700 gph (£200-odd retail, £40 from the boat jumble I visited). Sorry I got the number wrong and incited your wrath.

This is from experience.

You now have a an electric pump apparently. I don't know what measurements you have carried out. You appear to be speaking from literature statements. The Op asked for experienced use. Hose without corrugation is mentioned in all literature to reduce friction losses.

A FLOATING log or other flotsam or jetsam, hitting and holing your boat ( as you seem to think you are invulnerable to any water ingress). I don't know how you think regular maintenance will stop something hitting you, but I realise you did not grasp the meaning of what I wrote

The film was about a boat holed by the corner of a container in calm-ish weather I think; so not a massive hole.

 

[Sailingsaves]

Wow, that'd be really annoying and disruptive to my sleep, not to mention pointlessly suck battery power. Also the pump, which on our boat has never seen water except the one time we tested it with the hose would spend all this time running dry. Your current setup with the sensor and override switch sounds a lot better to me.

Yes. I forgot about the noise. It is irksome every five minutes or so; especially as the pump reverberates through the grp.

Good point !

 

[geem]

I'm afraid I have to disagree with your description "safety equipment". Most automatic bilge pumps have very limited pumping ability - OK, they'd perhaps cope with the leaky lazarette you mentioned, but that's hardly a life-threatening problem.

Bilge pumps are rated at zero head so a Rule 3700gph (yank gallon) will do 2450gph at 2m head. We have enough automatic pump capacity to pump over 19000litres per hour. A 2" diameter hole 1m below the surface will fill your boat with 20,000 litre per hour unchecked. Our main bilge pump is wired to an alarm such that every time it runs, it sounds. Its never worrying unless it doesnt turn off! Its never happened yet but very happy to have it alarm if the pump runs as I want to be looking for the problem ASAP not waiting for a high level alarm to sound.

 

[benchmark]

I am a bit surprised about the OPs definition of an automatic bilgepump. Maybe it’s me that has it wrong but I always assumed that an automatic pump was one that did not run unless there was water to activate a floater or electricsensor switch.
Then we have manually activated bilgepumps that only start by the manual flick of a switch.
We also have manual activated pumps linked to a timer that run at a preset time interval wether or not there is water in the bilge.
Then we have backup hand pumps.

That said, the perfect setup for a boat in my view is a pump that is activated by a water sensor/floater switch in case of water ingress. With a manual overide switch in the cockpit and an acoustic alarm that indicates if it is activated.
Also with a hand pump as backup Incase of powerloss.

 

[BelleSerene]

I am a bit surprised about the OPs definition of an automatic bilgepump. Maybe it’s me that has it wrong but I always assumed that an automatic pump was one that did not run unless there was water to activate a floater or electricsensor switch.

Hi - thanks for thoughts. I’m the OP and was surprised too at the definition, but it’s the industry’s, not mine. Google it.

A manual electric bilge pump either runs off a switch or can be made automatic with the addition of an external float switch. A triplex switch could make this selectively; ON, OFF, or AUTO

Auto bilge pump usually has an internal float switch or reed sensor. There are also models where a computer turns them on every couple minutes and if there is no water back pressure, turns them right back off.

I agree with the majority view above that ‘automatic’ pumps are a silly idea as the occasional noise they make in running for a few seconds to check for water by detecting suction pressure will be annoying. I guess the benefit is that by periodically running they ensure the impeller doesn’t get clogged. I won’t be buying one - I’ll get another ‘non-automatic’ and a Water Witch electronic water detector.

 

[sealegsjim]

The switch on my bilge pump is on/off/auto. I set it to auto and it only runs if there is water in the bilges. It doesn't "check" for water by running periodically that would drive me crazy

 

[BelleSerene]

The switch on my bilge pump is on/off/auto. I set it to auto and it only runs if there is water in the bilges. It doesn't "check" for water by running periodically that would drive me crazy

That’s right, so it’s what the industry calls a non-automatic type with an integral water sensor (or float switch) which the ’on’ setting overrides.

That’s what I have, and that’s what I’m going to replace it with.

 

[NormanS]

Remember that an automatic bilge pump is not selective in what it pumps.

I used to winter a previous boat in the Caledonian Canal, and a large boat close by pumped about 1000 litres of diesel into the canal when a fuel tank sprung a leak. The owner did not win any Brownie points for that episode.