Are manual bilge pumps useless?

A

alexlago

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Hello,

The outflow rate of those pumps seems to be pretty low, so if one really needs to take out a huge quantity of water, a bucket would do the job faster.

If the batteries are empty and one can't use usual bilge pumps, one may just connect a pipe from the bilge to the engine raw water intake, run the engine, and it would probably flush out more water than the manual bilge pump (whilst allowing the skipper to focus on manning the boat).

So I really wonder about the real use of those manual bilge pumps...
 
alexlago said:
Hello,

The outflow rate of those pumps seems to be pretty low, so if one really needs to take out a huge quantity of water, a bucket would do the job faster.

If the batteries are empty and one can't use usual bilge pumps, one may just connect a pipe from the bilge to the engine raw water intake, run the engine, and it would probably flush out more water than the manual bilge pump (whilst allowing the skipper to focus on manning the boat).

So I really wonder about the real use of those manual bilge pumps...
Click to expand...

My first boat had a diverter valve to switch engine cooling between bilge and sea and it cleared the bilges very quickly
 
indeed !
so I plan to get rid of the manual pump, and install a T connector on the raw water intake pipe, the T connector being connected through a valve to a pipe going to the bilge.
 
alexlago said:
indeed !
so I plan to get rid of the manual pump, and install a T connector on the raw water intake pipe, the T connector being connected through a valve to a pipe going to the bilge.
Click to expand...

You may be surprised how little water is pumped through the engine. Try putting a bucket under the exhaust and seeing how long it takes to fill.

There's also a risk of lumps of debris getting sucked up and blocking the engine, so you'll need a strainer on the pick-up pipe.
 
good remark...
though it would be worth to compare the respective outflows of the engine pump and of the manual pump...manual pump seems to pump very little too....(ok, i've got skinny arms...)

yes, a strainer there may be necessary.
 
The trouble with buckets is that in anything bigger than a Wayfarer you can't just sit in one place, filling it up and chucking it over the side. The bucket full of water may well be equivalent to quite a few seconds of pumping on the bilge pump, but by the time you have either passed it to a fellow crew member up the companionway, or gone with it yourself - with all the spills that will happen along the way - I bet that you move water faster on a bilge pump.

In practice, bilge pumps are only really relevant to fairly small leaks - anything significant is going to sink the boat within a short period of time irrespective of what mechanism you have to get the water out.
 
Many moons ago I was helping to deliver a yacht. The wind dropped, we were at risk of being run over by shipping and just to top things off, the impeller on the (supposedly just serviced before the trip and in great condition - yeah right, pull the other one it's got bells on!) engine packed up and there wasn't a spare on board. The starter solenoid packed up as well, so we jumped bypassed that with a spanner across the terminals, but of course that meant that we couldn't run the engine in bursts - there was no guarantee we'd get it going again.


We disconnected the manual bilge pump, plumbed it into the raw water intake, screwed the pump onto an upturned sole board and then I manually pumped cooling water through the engine for a couple of hours until we got to a safe port. When we got in and the owner was there waiting for us he was very lucky indeed that he was holding a cold beer for me or he might have been going for a swim. I don't know if you've tried pumping solidly for a couple of hours, but it was hard work even for the young super fit racing snake that I was then!

My boat has a spare manual bilge pump in the spares box in the lazarette. I doubt I'll ever need to repeat that experience, but if I do, it's handy to know that I've got the means to make it all work.
 
alexlago said:
good remark...
though it would be worth to compare the respective outflows of the engine pump and of the manual pump...manual pump seems to pump very little too....(ok, i've got skinny arms...)
Click to expand...

A typical small manual bilge pump will output around 20 gallons a minute. A typical small engine pump will output around 15 gallons a minute. If you do a search, you'll find previous threads on this subject, eg http://www.ybw.com/forums/showthread.php?268953-Raw-water-pump-as-emergency-pump
 
alexlago said:
Hello,

The outflow rate of those pumps seems to be pretty low, so if one really needs to take out a huge quantity of water, a bucket would do the job faster.

If the batteries are empty and one can't use usual bilge pumps, one may just connect a pipe from the bilge to the engine raw water intake, run the engine, and it would probably flush out more water than the manual bilge pump (whilst allowing the skipper to focus on manning the boat).

So I really wonder about the real use of those manual bilge pumps...
Click to expand...

err... surely, if the "batteries are empty", then neither can one start the motor to use it for pumping out?!
 
There are handpumps and handpumps of course. The 1902 pilchard driver I was on had the original lead pump, a 4in diameter vertical lead tube in the deck with a wood plunger with a leather valve on a tee handle, it pumped as much as you could haul up: 50mm radius sq x pi x 600mm length = 4.7litres per stroke.
When you arrive on board to find water in the bilge, or someone checking it for you does, electrics dicky, no engine etc a hand pump seems the logical solution.
 
The direct answer to the question you pose is NO.

A manual bilge pump is useful no matter how much you try to construct scenarios that suit your argument.

You just have to be aware of its characteristics and limitations and recognise that it can do things the alternatives you posit can't. It performs a useful role in dealing with unwanted water inside the boat.

However you should also spend (more) time on doing things that prevent water getting into the boat in the first place.
 
alexlago said:
Hello,

The outflow rate of those pumps seems to be pretty low, so if one really needs to take out a huge quantity of water, a bucket would do the job faster.

If the batteries are empty and one can't use usual bilge pumps, one may just connect a pipe from the bilge to the engine raw water intake, run the engine, and it would probably flush out more water than the manual bilge pump (whilst allowing the skipper to focus on manning the boat).

So I really wonder about the real use of those manual bilge pumps...
Click to expand...

I suggest that you try it.

A full bucket holds about two gallons but a bucket in use may hold one. You now have to get your bucket from the bottom of the boat, through the companionway, across the cockpit and into the sea.

You will be doing well if you manage two gallons a minute. Now keep it up for an hour.

Come back and tell us about how you did the job faster.
 
Minn said:
I suggest that you try it.

A full bucket holds about two gallons but a bucket in use may hold one. You now have to get your bucket from the bottom of the boat, through the companionway, across the cockpit and into the sea.

You will be doing well if you manage two gallons a minute. Now keep it up for an hour.
.
Click to expand...

..or nineteen hours as my bro and wife did
 
Minn said:
I suggest that you try it.

A full bucket holds about two gallons but a bucket in use may hold one. You now have to get your bucket from the bottom of the boat, through the companionway, across the cockpit and into the sea.
You will be doing well if you manage two gallons a minute.
Click to expand...
concerning my boat, i can throw a bucket directly from the galley onto the cockpit, without climbing the stairs, no need to throw outside (there are 2" cockpit drains to take the water out).
This said, that's why I mull to use the engine pump as an emergency....
Anyway... if one has got a leak more than "one gallon a minute"....maybe it's time to think about how to plug the hole BEFORE pumping out...
 
alexlago said:
concerning my boat, i can throw a bucket directly from the galley onto the cockpit, without climbing the stairs, no need to throw outside (there are 2" cockpit drains to take the water out).
This said, that's why I mull to use the engine pump as an emergency....
Anyway... if one has got a leak more than "one gallon a minute"....maybe it's time to think about how to plug the hole BEFORE pumping out...
Click to expand...

Until you have enough water in the boat to submerge your cockpit drains.

An occasional “wind up thread” is fun but this sort of trolling is irresponsible.
 
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