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Old 08-03-2014, 14:12   #1
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Lightbulb My crash pump idea

I've been thinking about this for a while, but it so happens that the guts of my boat (1985 Tashing Baba 40) that now would be an easy time to install a crash pump. Before I spend $300 having missed something obvious, please poke holes in the idea.

Liberty pumps makes a 110V 1/2 HP sewage pump with a 2" discharge. It's rated at 8400 GPH w/ 5 ft head. It pulls 23A starting and 12A running. This model is non-automatic i.e. no float

Liberty Pumps LE51M-2 - 1/2 HP Cast Iron Sewage Pump 2-Inch w/ 25' Cord Non-Automatic

It will fit quite well in the lower pit of the bilge. It's no where near 5' from the bilge to the waterline where the outlet would be, but let's use 8400 GPH for figuring.

My installation thought is this:

Epoxy some rails to the side of the pit and make a hold-down collar that bolts to the rails.
Run a 2" vented loop as high as I can and then back down to a thrihull just above the waterline on the stern.
Install a 30A circuit off the inverter to an outdoor-rated switch box and outlet in the lazarette.
Run the 25' cord from the pump to the lazarette It's 10' maybe, so I have 15-is feet of cord left.

I know my inverter will handle the surge (my A/C pulls similarly). I also have a Honda EU2000i that should be able to run it.

This should cover 2 main scenarios:

1 - I blow a hose / through hull / whatever, and am taking water faster than my electric pump (Rule 3700) can clear it. Answer: flip the switch, start the engine, and go deal with the leak. Even if I am taking water on faster that the 8400 + some percentage of 3700 I can remove, it sure buys me a lot of time.

2 - I take a real hit, and even with pumps running, I end up in knee-deep water that has shorted out my batteries and inverter before I get it stabilized. I pull the generator out, unplug from the now-dead outlet in the lazarette, plug into the generator, and proceed to de-water. As long as I have patched the hole well enough to flow <= 8400 gal, I'm somewhere between holding steady and slowly emptying.

For some of the obvious faults:
I always have between 5 and 10 gallons of gasoline on deck ( dink tank + 5 gal jerry can)
The generator lives in the lazarette with not much on top of it, and it gets run at least once a week.

Granted if we are pitching and rolling all over, a portable generator is a fail. But, if we are pitching and rolling that hard and taking on more that 8400 gal / hr, the game is probably up.

Though / obvious fails / comments of any kind appreciated!

Thanks,
Dave.
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Old 08-03-2014, 23:47   #2
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Re: My crash pump idea

The pump requires almost 3kw to start. The Honda only puts out about 1600w max. Trying to start the pump will shutdown the Honda.
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Old 09-03-2014, 00:22   #3
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Re: My crash pump idea

No chance you could just permanently connect a centrifugal pump to the diesel engine?
It doesn't use any power unless the water rises above the inlet.

Older diesels will run under water with a bit of prior pimping.

That's kind of gold standard availability and reliability, when talking crash pumps.
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Old 09-03-2014, 05:17   #4
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Re: My crash pump idea

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Originally Posted by Viking Sailor View Post
The pump requires almost 3kw to start. The Honda only puts out about 1600w max. Trying to start the pump will shutdown the Honda.
That is one of the question marks. The Honda is rated at 2000w and it has a 4 second delay on it's over current protect, but this pump might very well exceed what it can support for even 4 seconds.

I had considered building a big-a** motor start cap somewhere and decided that was entering the "there I fixed it" zone.

There is another pump with a soft start that pulls 12A starting and 7A running, but is only rated 6300 GPH @ 5'
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Old 09-03-2014, 05:19   #5
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Re: My crash pump idea

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Originally Posted by Andrew Troup View Post
No chance you could just permanently connect a centrifugal pump to the diesel engine?
It doesn't use any power unless the water rises above the inlet.

Older diesels will run under water with a bit of prior pimping.

That's kind of gold standard availability and reliability, when talking crash pumps.
There 's room for one - the "pit" is right below the engine. I tend to reach for electric because that is that I know, but I will research a mechanical solution. Appreciate the idea!
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Old 09-03-2014, 07:35   #6
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Re: My crash pump idea

I would vote with Andrew. One type is a clutch driven pump that runs off the engine.

There are also drive shaft driven pumps if you have the room that de-water at a very high rate.. Check out Fastflowpump.com

And lastly there is a stand alone such as a honda gas powered water pump. Although this would require a great deal more maintenance to make sure the fuel doesn't gum up. You would need to run it regularly
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Old 10-03-2014, 03:26   #7
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Re: My crash pump idea

I've thought about the engine driven pumps, and I'd love to have one. Then I got to thinking about our standard start-the-engine routine, which takes 5+ minutes to get the engine started and running smoothly. Not viable in an emergency. (Yes, that's on the list to figure out why its hard to start, but that's another rabbit hole).

I'll look into the stand-alone pump - I haven't really researched them much. I also think you're right on the startup current. I can go down one size in pump and drop my startup current quite a bit and /or ask myself how realistic it is that I would ever run the pump off the Honda.

Thanks all!
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Old 10-03-2014, 03:42   #8
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Re: My crash pump idea

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Originally Posted by ontherocks83 View Post
I would vote with Andrew. One type is a clutch driven pump that runs off the engine.

There are also drive shaft driven pumps if you have the room that de-water at a very high rate.. Check out Fastflowpump.com

And lastly there is a stand alone such as a honda gas powered water pump. Although this would require a great deal more maintenance to make sure the fuel doesn't gum up. You would need to run it regularly
That looks like the Erickson pump reborn (discontinued)

They CAN be mounted on a layshaft and driven from the crankshaft, perhaps via an HTD belt to minimise belt tension needed; they don't have to be on the propshaft, which not all boats have, and even if they do, the location may not be suitable. An added bonus: you can run layshaft mounted pumps in neutral, unlike the propshaft installation.

They don't require a clutch in either location, which is a bonus feature.

But one negative: They work so well they may conceal the presence of a major water ingress which started while motoring, at least, until you turn off the engine!

PS: It would be a shame to let the engine starting issue decide your choice of crash pump. It really needs to be solved, as you rightly state !
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Old 10-03-2014, 07:53   #9
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Re: My crash pump idea

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Originally Posted by dstrout View Post
That is one of the question marks. The Honda is rated at 2000w and it has a 4 second delay on it's over current protect, but this pump might very well exceed what it can support for even 4 seconds.

I had considered building a big-a** motor start cap somewhere and decided that was entering the "there I fixed it" zone.

There is another pump with a soft start that pulls 12A starting and 7A running, but is only rated 6300 GPH @ 5'
I have stalled out my Honda 2000 with a 10 amp circular saw: the blade binded on a knot and that was that. It started again after a brief delay, but that and some other anecdotal tales of high "kickoff" amperages defeating the Honda's inverter have convinced me that whatever its many virtues, the Honda's advertised limits are real and not to be exceeded.

I have an AC March pump to work a Mermaid A/C-heat pump setup (which runs on ship's DC). The March pump takes 17 amps to kick and 6 amps to run. I've been told that this is right on the bubble for a Honda 2000 to handle and may not always work. It's convinced me that getting a pair of Hondas, one with the "companion" setup, is the way to go if I care to have both redundancy in my portable genset department and sufficient oomph to run A/C on the hook.

Your mileage, of course, may vary, but I think that particularly for a critical emergency function like massive bilge pumping, I would have my power requirements safely exceeded by a wide margin.
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Old 10-03-2014, 08:12   #10
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Re: My crash pump idea

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Originally Posted by dstrout View Post
That is one of the question marks. The Honda is rated at 2000w and it has a 4 second delay on it's over current protect, but this pump might very well exceed what it can support for even 4 seconds.

I had considered building a big-a** motor start cap somewhere and decided that was entering the "there I fixed it" zone.

There is another pump with a soft start that pulls 12A starting and 7A running, but is only rated 6300 GPH @ 5'
There's also the idea of "staged" pumps: the 3700 at the bottom and a second 3700 at the 12 inch level, or having the bigger sump or crash pump at some point where the primary, first line of pumping would be overwhelmed.

This is a problem I will also have to address at some point as I have an equally cavernous bilge.

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Old 10-03-2014, 08:20   #11
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Re: My crash pump idea

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Originally Posted by Andrew Troup View Post
No chance you could just permanently connect a centrifugal pump to the diesel engine?
It doesn't use any power unless the water rises above the inlet.

Older diesels will run under water with a bit of prior pimping.

That's kind of gold standard availability and reliability, when talking crash pumps.


Could look into on of these Fast Flow Emergency Bilge Pump

Two birds with one stone it's a blower when not taking on water.

The 120 electric sounds like a nice idea if you have shore-power, put a float and alarm in with it and no batteries to run down.
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Old 10-03-2014, 09:38   #12
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Re: My crash pump idea

Dave I like your thinking in regards to pumps being there to buy time to make repairs.

I don't know how many times I've heard someone argue that bigger pumps or more pumps are a waste of money because if you get an X size hole they won't keep the boat afloat.

Pumps aren't supposed to keep the boat afloat, the boats hull is. Pumps just buy time to fix the hull.

I like to be able to use my engine cooling pump to remove water in an emergency. Typical sailboat engines have pretty small pumps and might not be worth the effort for you.

A lot of good ideas in this thread.
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Old 10-03-2014, 10:05   #13
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Re: My crash pump idea

Why do you feel the need ? Kinda overkill ! If its a round hole , jump over and pound a plug in it ! If its a jagged hole , fother it . I once lost an inch and a quarter thru-hull and after an hour water was not up to the floor boards . Manual always works , for what you will spend you could buy three or four very good manual pumps .
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Old 10-03-2014, 10:08   #14
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Re: My crash pump idea

As an aside , I say that the lowest electric pump in your bilge should discharge in the cockpit at the helmsmans feet . Maybe a small pump , but even if you are motoring the helm will know something is wrong . If you are asleep down below the running water should wake ya up .
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Old 10-03-2014, 19:23   #15
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Re: My crash pump idea

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Why do you feel the need ? Kinda overkill ! If its a round hole , jump over and pound a plug in it ! If its a jagged hole , fother it . I once lost an inch and a quarter thru-hull and after an hour water was not up to the floor boards . Manual always works , for what you will spend you could buy three or four very good manual pumps .
Well, I can't speak to your experience, but I look at some of the hull breach flow rates, and it doesn't take a very big hole very far down to outstrip a standard bilge pump. Look at Breached hulls, swamped hulls, and bilge pumps | M.B. Marsh Marine Design for instance. A 2" hole ~5 ft down is 10,000 GPH. That's 166 gal / minute, which is roughly 1300 lbs of additional weight per minute.

If I have a crash pump that can move an honest 6000 GPH, that reduces my weight gain to ~500 lbs / minute. I'm still sinking, but I'm sinking 2.5 times slower. So in 10 minutes, I've gained 5000 lbs with the crash pump, and 13,000 lbs without. On a 30,000 lb boat, 5000 lbs doesn't scare me. 13000 lbs does.

It's sort of like the theory that we are all dying. The goal is to do it as slowly as possible.

It's also not just math. More time means less panic. Less panic means fewer mistakes. Fewer mistakes means less chance of making the situation worse instead of better. And better is better than worse.

Anyway, that's my logic train, for whatever it's worth.
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