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Old 11-03-2010, 10:40   #1
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Bilge Pumps

One of my projects this spring is to upgrade the bilge pumps on our boat. Sinking is of course one of the worst nightmares of all of us.

Presently we have one single smallish submergable electric pump in the main bilge, and one lever-operated manual diaphragm type which can be switched to evacuate either the main bilge or the completely separate engine compartment bilge. This seems wholly inadequate to me.

I have ordered a beefier Rule 3700 pump to put alongside the original one in the main bilge. It will be wired to a float switch positioned somewhat higher than the switch for the original pump, so that it comes on only if the water is rising faster than the small pump can handle. This pump will also be wired to an alarm. If it starts working, then we have a problem, and the alarm will let us know about it.

What do you guys think -- is this enough?

I think about an engine-driven emergency pump but what a pain in the a** to install.

Another idea I had was to add one more big Rule electric pump, maybe this time the Rule 8000 which has two 4000 pumps working in tandem. To create some redundancy I would wire it to -- the engine start battery. Not the main 24v house bank. The engine start battery has its own alternator and is completely separated from the 24v house bank. It seems to me that this would be almost as good as an engine-driven pump. I could wire it with a relay to prevent its being used without the engine running. The smaller 12v alternator should be able to handle it; it is 65 amps @12V nominal output (which means probably good for a realistic half that at least) and the pump draws 31 amps @ 12v.

All these pumps going at once could move probably 9,000 gallons an hour or 150 gallons per minute over a 1.5 meter head. That should be equal to the best of the engine driven pumps, and should give me a fighting chance to fix a broken through-hull or something of that order without sinking.

What do you all think about that? What do you use in your own boats?

One problem with this setup is that it will require adding two more discharge points (I presume I can't tee the discharge lines together or tee them into a cockpit drain?). This presents another set of problems. But I don't see how, in any case, I can avoid adding discharge points.
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Old 12-03-2010, 02:40   #2
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Nobody has an opinion on this? What's happened around here?
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Old 12-03-2010, 04:33   #3
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Dockhead its sounds like a plan, but remember that electric bilge pumps will never move the amount of water that they advertise. And the longer the run and with bends its even less.
having a bilge pump hooked up the the start battery also is not the best way to do it IMO, because it could mean your engine couldn't start after being run down by the pump, assuming you were not there.
The large pumps also need pretty big diameter hose.
I have a smaller jabsco diaphram pump with a no return valve in the lower bilge. Above it a rule 3700 pump and a additional rule 3700 next to it not yet hooked up, and then a whale manual in the cockpit.
I would like one of the jabsco trash pumps on the main engine, but don't have the money for one right now, and not sure how I would hook it up to my perkins with the serpentine belt. I would put on on a DC genset, or AC genset with a PTO in the future. (one day perhaps)
The other problem with the large pumps are the current they draw, and switch wise it can be a problem to set up.
If you can swing the jabsco trash pump go with that.
I would.
Bob
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Old 12-03-2010, 05:05   #4
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Dockhead, at the very least I would also replumb your engine raw water pump to allow for emergency bilge pumping too. It's simple and effective...even if ALL your electrics fail...
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Old 12-03-2010, 05:11   #5
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Do you have a bow thruster with its own battery? if so how about a pump up the sharp end.

We did convert on of our manual pumps to electric by inserting a whale bilge/shower type inline with the existing manual pump. It was an idea discussed on the moody Owners Association website. The advantage to the large diaphram whale pumps is they can tollerate bits and pieces in addition to water at the expense of moving a high volume of water.

We then plumbed in a smaller auto pump into the engine compartment. I worry that if we are top side and travelling under engine a hose could burst and we wouldn't know about it until the floor boards start floating out of the companion way. So a small auto that pumps into the cockpit and out through the scuppers. It means you get wet feet if the engine starts a major leak, just what is required a on a cold night to wake up the watch to impending doom.

Final stage (still to be completed) is one big HD 12v pump, however our bilges have less than 3" in height so choice and location need thinking about.

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Old 12-03-2010, 06:35   #6
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Quote:
Originally Posted by Pete7 View Post
Do you have a bow thruster with its own battery? if so how about a pump up the sharp end.

We did convert on of our manual pumps to electric by inserting a whale bilge/shower type inline with the existing manual pump. It was an idea discussed on the moody Owners Association website. The advantage to the large diaphram whale pumps is they can tollerate bits and pieces in addition to water at the expense of moving a high volume of water.

We then plumbed in a smaller auto pump into the engine compartment. I worry that if we are top side and travelling under engine a hose could burst and we wouldn't know about it until the floor boards start floating out of the companion way. So a small auto that pumps into the cockpit and out through the scuppers. It means you get wet feet if the engine starts a major leak, just what is required a on a cold night to wake up the watch to impending doom.

Final stage (still to be completed) is one big HD 12v pump, however our bilges have less than 3" in height so choice and location need thinking about.

Pete
Yeah, problems, problems. Hmm.

It makes me really get Sundeer envy. Those boats have NO through hulls in the main volume of the hull. They have separate aft engine rooms separated from the rest of the boat with waterhead bulkheads, and ALL of the through-hulls are either there or in the watertight forepeak. They would be very hard to sink.

That's an interesting idea about the electric pump mounted in-line with the manual one. Will it just pump right through the manual pump? Doesn't slow it down? And will the manual pump be able to pump through the electric one?

I have just realized that the engine room on my boat has its own bilge which is not interconnected with the main bilge. It's got no bilge pump at all except for the manual one. Thanks, Moody! So I realize now that I have to install at least two new pumps.

I love your idea about pumping the engine bilge into the cockpit. Great alarm! I think I'm going to put alarms in both bilges, with lights in the cockpit. Thinking about all this can make you positively paranoid about sinking.
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Old 12-03-2010, 06:43   #7
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Originally Posted by bobfnbw View Post
Dockhead its sounds like a plan, but remember that electric bilge pumps will never move the amount of water that they advertise. And the longer the run and with bends its even less.
having a bilge pump hooked up the the start battery also is not the best way to do it IMO, because it could mean your engine couldn't start after being run down by the pump, assuming you were not there.
The large pumps also need pretty big diameter hose.
I have a smaller jabsco diaphram pump with a no return valve in the lower bilge. Above it a rule 3700 pump and a additional rule 3700 next to it not yet hooked up, and then a whale manual in the cockpit.
I would like one of the jabsco trash pumps on the main engine, but don't have the money for one right now, and not sure how I would hook it up to my perkins with the serpentine belt. I would put on on a DC genset, or AC genset with a PTO in the future. (one day perhaps)
The other problem with the large pumps are the current they draw, and switch wise it can be a problem to set up.
If you can swing the jabsco trash pump go with that.
I would.
Bob
Yeah, I think that's smart. I will be on the boat next week and have a look at possible mounting positions for the trash pump. If I can find a spare pulley it might be practical. If not, then not.

I'm still thinking about a "last ditch" pump in the main bilge wired to the engine start battery. A Rule 8000 12v draws 31 amps, which the smaller 12v alternator can handle, and moves a ton of water. It would be completely redundant to all the other electrics. I remember when our old boat got hit by lightning last year, it fried every electrical bit on board -- except the engine start battery and system, because that was not connected to anything at all. It seems to me that such a setup would be roughly similar to a mechanical trash pump in terms of your chances that it would work when other things had failed since it is completely separated from all the other electrical equipment on board.

In order to prevent running down the engine start battery, I could simply put in a relay which requires the engine to be running, for it to work. Anyway, this one would be mounted higher than the others and would only come on if the boat were actually in real danger of sinking. There would be two other, lower pumps ahead of it. So theoretically it should never switch on anyway.

Or maybe even just put it on a manual switch and forget the automatic part. No worse than the trash pump, which you have to switch manually, from the engine compartment no less.
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Old 12-03-2010, 06:49   #8
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Another thing which gives me chills in researching bilge pumps, is all the tales of pump float switches failing constantly (and reports of sinkings as a result).

Maybe one of our electrical geniuses could opine on this:

In order to guard against a float switch failure, couldn't you wire two of them in parallel? So if one failed, the other would keep going. I can't think of any reason why they would interfere with one another. Either one, or both, having a closed circuit would route power to the pump, right? Anybody do this?
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Old 12-03-2010, 07:35   #9
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It seems to me you are over engineering this. But I will add a couple of comments. Never tee a bilge pump into another bilge pump or drain I have several good horror stories for this but will save that for later. Yes you can use 2 float switches but with a high water pump and alarm do you really need to? Switches that fail are ones never looked at by the owner. I would put some of this time and effort into keeping the water from getting in in the first place. Check all underwater fittings and hoses regularly, fix replace when needed. Good cared for fittings rarely just fail. As for your pump system remember the more complicated the more likely not to work when needed most. If you are really worried add a crash pump to the engine. I do not recommend teeing into the intake, if you do and suck up some crap, you will be sinking without the engine to help as that will now overheat. KISS. Just my thoughts

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Old 12-03-2010, 08:34   #10
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It seems to me you are over engineering this. But I will add a couple of comments. Never tee a bilge pump into another bilge pump or drain I have several good horror stories for this but will save that for later. Yes you can use 2 float switches but with a high water pump and alarm do you really need to? Switches that fail are ones never looked at by the owner. I would put some of this time and effort into keeping the water from getting in in the first place. Check all underwater fittings and hoses regularly, fix replace when needed. Good cared for fittings rarely just fail. As for your pump system remember the more complicated the more likely not to work when needed most. If you are really worried add a crash pump to the engine. I do not recommend teeing into the intake, if you do and suck up some crap, you will be sinking without the engine to help as that will now overheat. KISS. Just my thoughts

Fair Winds
Thanks; that's useful advice.

I have found a nice switch/alarm panel, not even an expensive one (!), called the Sea Dog Bilge Alarm. See: Sea-Dog Line: 422035-1 Instructions. Costs only $23 and seems to be well engineered and sturdily built out of aluminum.

You wire two float switches into it. The lower one activates the pump. If the water reaches the upper one, the alarm goes off, and the pump is activated if it's not already on. I think I will just put each bilge pump on one of these, then every pump is failsafe and there are different levels of alarms.

A bit overengineered, I know, but I really want the pumps to be there if I ever need them.

As to the crash pump, I'm still thinking.
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Old 12-03-2010, 09:07   #11
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Hi,

FWIW I've personally think if you keep an good eye on all your through hull fittings the chance of one ever giving up is zero. But now I've said that when I next visit my boat it will probably be sunk!


But one further consideration could be to install a simple switched high volume (we've a Johnson) pump with a 10 metre fexible hose. We can then use the intake at the water location.
It is useful on our boat to empty any filled voids twix glassed in stringers / frames.

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Old 12-03-2010, 10:46   #12
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Panels look ok but I would replace the 3 position switch with a 2 position, NEVER wire your pump so it can accidentally be turned completely off! Can't tell you how many floodings have looked into because somebody with one of those Rule panels very similar to the one you are looking at left the switch in the off position after manually clearing the bilge.

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Old 12-03-2010, 11:29   #13
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alternative installation

Quote:
Originally Posted by Dockhead View Post
I have ordered a beefier Rule 3700 pump to put alongside the original one in the main bilge. It will be wired to a float switch positioned somewhat higher than the switch for the original pump, so that it comes on only if the water is rising faster than the small pump can handle. This pump will also be wired to an alarm. If it starts working, then we have a problem, and the alarm will let us know about it.
You might want to consider not only positioning the float switch higher, but installing the pump higher as well. This is the way it's been done on my boat. The smaller pump is the working pump, not only doing the dirty work but also getting dirty. The bigger pump, eight inches higher than the working pump, has never gotten wet. It has its own two-inch hose so that it can move a serious amount of water. It's only there for an emergency situation, and if such a situation ever happens you don't have to worry about a pump pre-clogged with dirt. Additionally, the bigger pump is alarmed. If it ever engages, everyone is going to know it.
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Old 12-03-2010, 19:43   #14
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The key to multiple bilge pumps is planning.

Separate Circuits for each
Heat shrunk connectors
Proper wire size (there are numerous sites or Gord who will tell you the current drop over length)
Use smooth hose not the corrugated crap
and remember that pumps are rated (advertised) at ZERO HEAD.

A hose with strainer that I made up to affix to an engine "saved my and the crews bacon" on the way to Bermuda once.
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Old 13-03-2010, 00:42   #15
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My bilge pump works...

I had my boat on the slip the other day, just the usual few boat bucks worth of paint etc., and while it was up I heard the bilge pump cycling every few minutes.

No problem I thought, just a bit of water running back through the boat.

But it kept on happening, so eventually I wandered back to see what was going on.

Turned out the angle of the slip was such that the water from the forward water tank was running back to the sink, and, as the sink drain was blocked, running down into the bilge where it activated the bilge pump and whoosh/splash...

Now, I'm not running any super powerful bilge pump, there must be at least 6' up to the through hull, and the switch is a standard Rule type that a few are not fond of, but this was pushing jets of water out from the boat, moving 5-10 litres with each pulse.

Did give me a happier feeling about my bilge pump though.
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