Automatic bilge pump for" leak management", a good idea?

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FairweatherDave

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In my leak thread I have described the fact I have weeping keel bolts that need attention. That IS going to happen. In the meantime the boat is taking on a litre an hour into the bilges. I am quite happy going to the boat weekly to monitor things but I cannot go over every two days, so I am considering a 12v automatic bilge pump. Normally I would do my own research but I don't have the time so I would really appreciate recommendations of products, or is it a bad idea. I'm not trying to clear gallons, just a litre an hour. I don't have solar panels but would take the domestic battery home to recharge periodically so comments on that also useful. The idea is to get the keels done in August, and £50 or even £100 seems good value to keep being able to sail through June and July. Thanks for any advice.
 
An electric bilge pump with float or similar switch are very common on boats. If only for emergency. So yes you should buy and fit an electric bilge pump with float switch.
I think you will find it works well. Just how long the battery lasts is another question. You obviously need a smallish battery so you can carry it home for charging. But that won't last so long.
I can only sugggest you fit the pump then watch it for a few hours to see how often and for how long it runs. If you measure or know the current drain of the pump you can calculate likely life of the battery. Count on 50% of rated amp hour of battery.
ie pump draws 1 amp is on for 1 minute every 15 minutes. That is 4 amp minutes per hour or 96 amp minutes per day. (1.5 AH per day.) so a 20 amp hour battery should be OK for a week. Car batteries while not ideal in design are usually about 40 AH. Get 2 from a car breaker. One on the boat one on charge at home.
However if you really love your boat you might fit 2 pumps for extra back up. Mount the second float switch up higher so it will normally not operate unless first fails.
good luck olewill
 
As suggested always taking a fresh battery to the boat with you is good also you could fit a solar charger or wind[always useful].
I have an auto bilge pump ...I would suggest one with an inbuilt float switch and non mechanical[as these can go wrong].
 
If you have to do this, think about the sump depth and total outlet pipe total volume. It is easy to get an auto bilge pump set up so that it pumps the sump/bilge near empty, then stops, but after 1-5 minutes the pint or three of water in the outlet pipe slowly trickles back to the sump and triggers the pump again. Pump then pumps it back up the pipe but not actually out of the boat, and stops. Repeat indefinitely.....

My boat came factory-fitted with a setup that did exactly this, on a long run (maybe 20 ft of pipe from well forward to a near-transom outlet) Put in a non-return valve, all that did was slow the repeat rate as inevitably bits of hair etc in the valve stop a 100% non-return.
 
For a known leak rather than a surprise one I would consider a timer to acivate maybe once a day (given that you consider once every 2 days if you were going there yourself). That way you avoid excess pumping from the back flow that jwilson rightly pointed out.
 
Dougal Tolan said:
For a known leak rather than a surprise one I would consider a timer to acivate maybe once a day (given that you consider once every 2 days if you were going there yourself). That way you avoid excess pumping from the back flow that jwilson rightly pointed out.
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Good thinking that man!! But OP will have to get timing right so as to limit pumping dry
 
pcatterall said:
Good thinking that man!! But OP will have to get timing right so as to limit pumping dry
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Thanks,my natural geek head would include a latch relay: timer generates brief trigger for relay which holds in until the float switch cuts the circuit on empty. if the bilge is dry the relay wont pull in so no dry pumping.
 
Dougal Tolan said:
Thanks,my natural geek head would include a latch relay: timer generates brief trigger for relay which holds in until the float switch cuts the circuit on empty. if the bilge is dry the relay wont pull in so no dry pumping.
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I can't see the point of a timer relay and a float switch. It's just another thing to fail in your absence but with no advantage, surely?

Richard
 
People around here with RIBs and open boats find the Rule pumps which switch on every few minutes and pump until they sense no water resistance, to be one of the more reliable solutions.
As others have hinted, keep the outlet pipe as short as possible.
 
My natural instinct is to fix it now as its only going to get worse. I've also not got much confidence in automatic bilge pumps operating when no one on board for extended periods.
 
If you do go for an automatic float switch bilge pump you need some way to tell holw long the pump runs for or to count the number of operations the pump runs so that you can tell if the leak is increasing over time.

I have automatic bilge pumps even through my bilge is always dry I have an 12 Volt electromechanical that counts up each time my bilge pump runs and I check and reset the count each time I visit my boat.
 
ghostlymoron said:
My natural instinct is to fix it now as its only going to get worse. I've also not got much confidence in automatic bilge pumps operating when no one on board for extended periods.
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I don't disagree with your first point but I've got 4 float operated bilge pumps - one in each hull and one in each engine compartment and I've tested them every year for the last 7 years and never had any issues.

Richard
 
Thanks for all the replies. There are some very helpful points made. Please bear in mind I have stated the pump is for a short term use and that I will still be actively monitoring weekly at least. I know it is a theoretical can of worms but for me I just need to choose the appropriate pump for this purpose. Obviously I can get advice from the chandlery but any recommendations of specific pumps here would be useful. I expect to be going to Force 4 on Monday and their website shows an awful lot to chose from.
 
FairweatherDave said:
Thanks for all the replies. There are some very helpful points made. Please bear in mind I have stated the pump is for a short term use and that I will still be actively monitoring weekly at least. I know it is a theoretical can of worms but for me I just need to choose the appropriate pump for this purpose. Obviously I can get advice from the chandlery but any recommendations of specific pumps here would be useful. I expect to be going to Force 4 on Monday and their website shows an awful lot to chose from.
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Battery drain is probably going to be your biggest issue.

You should be able to get the current draw of the pump before buying it, so you can estimate the drain on the battery. Make conservative assumptions about how frequently it would operate and for how long.

The pump is probably going to be a more efficient consumer of power if it operates less frequently in deeper bilge water, but that might be a problem for other reasons. Still worth considering when setting up the float switch.

Anything you can do to keep your batteries topped up will really help stop their useful life being shortened. I guess shore power is out of the question.
 
FairweatherDave said:
Thanks for all the replies. There are some very helpful points made. Please bear in mind I have stated the pump is for a short term use and that I will still be actively monitoring weekly at least. I know it is a theoretical can of worms but for me I just need to choose the appropriate pump for this purpose. Obviously I can get advice from the chandlery but any recommendations of specific pumps here would be useful. I expect to be going to Force 4 on Monday and their website shows an awful lot to chose from.
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this bilge pump
http://www.force4.co.uk/department/brands/rule/rule-500-bilge-pump-6-gallonsmin.html
This float switch
http://www.force4.co.uk/department/brands/rule/rule-automatic-float-switch.html

a length of 19mm braided hose and a skin fitting. If you dangle your hose over the side make sure it can't get into the water or you will sink your boat.

Solar panels are cheap as chips, get one and you don't need to carry your battery around (and rot your clothes) 50W and a £10 controller will run this lot as long as you're not sinking. Make sure the float switch is installed 6" or so above the pump.
 
Been studying people's replies a bit.
1. This back flow issue seems to defeat the point of the pump. I presume it is the idea of debris stopping the valve from closing. Providing the bilges remain relatively clean and the outflow pipe is short and I clean the filter regularly surely I get round that?
2. I like the idea of the wave activated pump, it looks designed for my issue of a minimal leak. Any comments?
3. Re siting of the pump or float switch, my bilges are shallow and wide. My target would be about 0.5 of an inch of water as opposed to the 1.25 to 1.5 inches of water I have found and feel unhappy about. More guidance on that would be great though obviously the pump instructions and chandlery might help.
4. I'm not much of an electrician, but I understand the thrust of lpdsn's post to look after my batteries.Pointers to the sort of timer I could wire in so that the pump only kicked in every six hours might be good as opposed to the float switch? The boat is on a swinging mooring but I don't have a problem with the idea of turning up with a charged battery in the dinghy each time I visit. This is a short term instalation.
Thanks for all the replies, this is a new area of boat ownership for me and one I have to get on top of faster than others............
 
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Done a bit more reading. The seperate float switch is "designed to prevent rapid on off cycling". Sounds like it kicks the pump on at a certain point but only switches it off after a significant drop in the water level, so the pump would seldom kick in in my situation, which sounds like a good thing. That sounds like they are a better system than the built in switches. Have I got that right? (My situation I estimate as a leak at 1 litre per hour). Apologies for the elementary questions :).
 
you will struggle to find a bilge pump that will leave only .5". this in itself rules out a float switch. the only way you'll manage it is with a pump with a pickup hose and a timed switch. you will need a very gentle pump as with small amounts of water it will just suck air.

the main point of a bilge pump is to cope if your leak gets worse. Other than that your current regime is probably as good as it gets.
 
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