bilge pumps

[solanderi]

Has anyone considered putting an actual dewatering pump somewhere on the boat just in case (one of those Honda gas jobs). 275 gallons per minute is pretty impressive.

http://www.hondapowerequipment.com/ModelDetail.asp?ModelName=wb30

I am sure that for something so important, I could find a 3 X 3 or 4X 4 foot space on my 45c. The next consideration would be where to store the one gallon of gas for it safely? Do they make a diesel one? Anyway, it is just an idea.....Maybe it would be right for someone who lives aboard or cruises extensively or does not have insurance, LOL.

I am just using Honda as an example but other companies make these products...Tecumseh, etc. The Honda unit uses a cast iron impeller, not good for continual sea water exposure but to have sealed and stored to ward off evil spirits...it would work.

 

[dwaynec]

This is a topic that I have a lot of interest in. Especially with the setup on our boat (48 Yachtfish). Essentially our boat has three bilge pumps to get the water out of the boat. One is in the lazerette area under the cockpit, one in the sump between the engines and one in the bow. These are all 2000GPH pumps. There are also two 1500GPH shower sump pumps, one in the engine room and the other in the bow. With the exception of the aft bilge pump, these are all routed to a single seachest on the port side of the engine room that exits at just above the waterline app. amidship.

I have often wondered if this setup is adequate in the event that alot of water started coming in at once? Should I consider adding a separate seachest and thruhull in the bow or some other place so that the engineroom and bow bilge pumps are not pumping through the same seachest? Should the shower sump pumps be routed someplace else?

I know that the bow bilge pump will not keep up with water coming in from the dock water supply. Found that out when a waterline burst and tried to fill the bow. Luckily we were on board when the line burst and it didn't get a chance to get really ugly.

What are your thoughts?
Dwayne

 

[egaito]

I know that the bow bilge pump will not keep up with water coming in from the dock water supply. Found that out when a waterline burst and tried to fill the bow. Luckily we were on board when the line burst and it didn't get a chance to get really ugly.

What are your thoughts?
Dwayne

Something isn't right here......

Any one of those bilge pumps should be able to keep up with the dock water supply.

While cleaning a bilge this past fall, I left a hose running constantly in the bilge of the boat I was working on to flush the bilge (and test the pumps). The water never got to the 2nd (forward) pump. When the float switch would trigger, it would run for about three to four minutes until it caught up, and then shut off for a couple of minutes. That was a single pump....1200 I think....

Things folks (yes, I'm folks too) tend to forget when sizing pumps is the lift required, hose restriction (corrugated hose, bends), voltage drop in wiring, and battery capacity. Bilge pumps are rated under the best conditions (full voltage and amperage, no restrictions on the outlet, no lift).

I saw an article once, Powerboat Reports perhaps, in which pumps were tested under "real life" conditions, and they didn't perform nearly as well as their ratings.

Can't blame the manufacturers for representing their products in their best light, but caveat emptor.

If you can check the voltage at the pump(s), while it's under load, it may give you a better idea of what's going on. You might improve the situation significantly by cleaning up connections, increasing wire size or reducing any restrictions in the run.

I've got a 2000 gph Rule that's not mounted....may have to try the "bucket test" to see what it really is capable of....I'll post results when I get it done.

-Ed G.

 

[dwaynec]

I know the hose and the wiring is good. I changed the hose shortly after we bought the boat because it had a hole in it. I discovered that when I was using the pump to get rid of some water in the bilge from giving it a cleaning. What a pain it was to change. There is no way anobody bigger than a skinny 6 year old can get down into that bilge short of taking up the floor. Voltage was a little low, about 12V but not what I would call unreasonable.

It could be the reason the pump didn't keep up is that the marina I was at had an abundance of water pressure, and maybe the inline regulator was not doing its job. I have changed that, but it doesn't really matter since I now run off the tank exclusively. I hate surprises.
Dwayne

 

[Traveler 45C]

THose of you adding 3700's, have you also added additional through-hulls to handle this or am I way off base here with the actual dynamics?

Your correct in that the sea chest will limit the discharge if it is not big enough. Tying it into another pumps discharge will also limit its output.
Be aware also that a 2000gph pump is rated at 13.8v in the horizontal position. With a significant head to push out of the boat the pump will push far less than 2000gph. And when the voltage to the pump starts dropping, so does its output. At 12v with a 6 foot head, the 2000gph pump will only push about 1100gph.

The Hi-water pumping system that I will be installing will use Rule 4000gph pumps (from Defender). They will discharge to their own thru-hull fittings. It will be completely separate from the normal de-watering pumps.

 

[Liquid Asset]

Another Idea for extra pump output is to add a engine driven Bilge pump. I have on on my Starboard engine, and If I did need it I has a manual clutch. But that thing will put out some serious water. I need to rebuild it as it is not in great shape, but thats another story.

They also make one with an electric clutch. I was thinking of installing that one on a float switch mounted much higher in the bilge. If I was running the engine it would imedietly start putting out a lot of water. It has a 2.5" hose in and out. Even though i would have to start the engine to make the pump work, it owuld be something that in an emergency could save my life.

 

[Traveler 45C]

Yea, that’s on my list to install also.

 

[Genesis]

If you normally have your genset up consider a POOL PUMP. They have an integral BIG strainer on the inlet and can push upwards of 100 gallons per MINUTE (that's a God-honest 6000 gallons per hour!) into a reasonable head.

They also won't burn up if run dry for a short period of time.

The only problem with them is that if your genset goes underwater it quits... but that's true if the power source for ANY pump goes under.

Engine-driven pumps are not a bad idea either.

My biggest concern with intake diverters (as many boats use) is that they require a dedicated someone in an emergency to "feather" the intake or you'll burn up the impeller in the engine (or the engine itself!) at which point you've just added to your troubles at a time you can least afford any new "surprises."

On a sportfish you have two major concerns....

1. The engine room. If this floods you're screwed. Most boats concentrate their attention there, and with good reason.

2. The Lazarette. This area is actually QUITE subject to flooding. The most common cause offshore is striking a rudder on some piece of underwater debris and shearing it off or damaging it or a strut sufficiently to punch a BIG hole in the bottom of the boat. Due to the way that these boats are usually built (e.g. fuel tanks back there) you have little or no access in many cases (ESPECIALLY with a strut problem!) to stanch the inward water flow.

I'm seriously looking at both of these areas for augmentation of my pumping capacity. The latter one is much harder to deal with appropriately than the former, but IMHO it is at least as likely to be the cause of a sinking.....

 

[hattitude]

I hesitate to bring this up because I don't remember the details, but...

A while back I read about an emergency pump that attaches to the shaft, behind the trans coupler. It looked kinda like a little turbo. In any case, it had a screen on the intake and a discharge hose to a thru-hull. The theory was if the shaft is turning, it's pumping. If water reaches the intake port it will pump it out. If there is no water, it will pump out air and help keep the ER cooler.

Thought it was an interesting concept, but didn't write anything down about it.

Bernie

 

[Genesis]

I've seen those - they work but are expensive and require a means of exhausting the water.

They also have some parasitic drag even when there is no water flow (through the air)

A gas-powered semi-trash pump will move a LOT of water. It will also "eat" small things without getting screwed up. The problem is where to store it when not in use (which is hopefully all the time!) and maintenance - if it won't start when you need it...... also, gasoline storage aboard a diesel vessel is a potential source of trouble. If you have a dink you have a source of gas though..... at least SOME gas.

 

[solanderi]

My idea was to get the gas (or even better diesel if available because it's safer and we have a nice fuel reserve) powered pump and completely shrink wrap the whole thing when it is brand new and store it somewhere out of the elements.

Keep your gallon of gas bungeed out of harms way in a nook in the cockpit (wherever that is) or on the flybridge in a safe fashion. Then if mayhem, chaos or disaster arises, you break that bad boy out, gas it up and pump away. I am not sure of the run time on one of these engines but I am sure it must be a few hours.