Bilge pump suggestion requested

My bilge at its deepest point is 2.75 inches.

Is anyone aware of an automatic bilge pump that can operate in that limited environment?

Is there an automatic device that can be retrofitted to operate in that environment?

 

3B,

Too little information to work on a solution. The short answer with your info is "no". The smallest bilge pumps I've heard of by any mfr are 3 3/4" high.

That doesn't help with your problem, though. How about a detailed description of the boat, your usage, whether there are any spaces open to the bilge, etc. Photos would help.

One possibility would be a float switch in the bilge and a small screened fitting on a hose running to a nearby larger space where a pump would be installed; I don't know if that's feasible in your case without knowing more specifics.

 

I have fouund this:

http://www.whalepumps.com/marine/product_list/8/55/

This is the dimensions:



Otherwise I'm with Charlie – the Whale-one I linked to doesn't really cut it in my book – I'd rather use a hose and have a proper one situated somewhere else.

 

The boat is a 1978 Iona 30 sailboat designed by Bob Perry. At it's deepest point, the bilge is approximately 2.75 inches. The Keel is bolted on. The floors are approximately 6 inches apart. As a result, there is a keel bolt between floors.

Currently, there is a Jabsco Water Puppy mounted in the engine compartment. It is attached to a manual switch and has a hose that extends forward of the keel. I replace the Water Puppy every 2 years because it loses sucking capacity and the motor gets weak. Furthermore, at its best, the sucking capability 12 feet from the pump is weak at best. This is not a dependable solution. A few years ago, I spoke to the folks at Jabsco to inquire about a pump with a lower profile or more powerfull pump. I told them of my use of the water puppy and the problems that I encounter. They commented that this was not the intended use for the Water Puppy.

 

3B,

Thanks for the description of your boat.

It might have been in at Boat US or West Marine's web site, but there was a review of about 20 different bilge pumps published a few years ago. One inescapable conclusion was that all models by all manufacturers were overrated. In other words the published capacities were based on "bench tests" with the pumps sitting in flat bottom shallow basins and the discharge hose perfectly level and only about 18" long. Nothing at all to do with the real world. The tests performed for the report found that, under typical boat conditions, with through hull fittings 2-3' above the bilge and hose lengths from 5-10', most pumps actual capacity was only about 40 -60% of the advertised capacity. It's interesting to see that some manufacturers have started to add phrases like "at 0' head" or "at free flow" to their descriptions.

At first I thought the Water Puppy guy was wrong, but after studying the specs carefully, I think he is right. The detailed description talks about routing both hoses so the impeller chamber is always flooded, and being sure no air gets into the suction hose. That last requirement is pretty hard to meet if the bilge bottom is flat and the pump has done its job and removed almost all the water!

Jabsco makes another type, a diaphragm pump. Diaphram pumps create a powerful suction force; they can be mounted as high as 7' - 10' above the water and still self prime. Don't do that, but it shows that they will do the job you need. The bad news is that a diaphragm pump is bulkier and costs about twice the price of a Water Puppy. The good news is: 1. It will definitely do the job - it's designed for dry starts and for pulling water up from a remote lower space - and 2. There are inexpensive rebuild kits to replace the diaphram and o-rings when they wear out. Instead of buying a new pump every 2 years, you'll be replacing the diapharagm, and that might be only every 3 -4 years. Here's a link to one model at one retailer; Jabsco has others and there are other manufacturers and distributors of that style pump.

http://www.go2marine.com/product.do?no=89266F

This should work if you have the space and don't mind the additional up front cost. Over the life of the pump, which should be at least 6 - 10 years, you'll save money ... and get the job done.

 

Its not so much as the pump being the problem as the boat itself. Are you sure there is nowhere else.

A positive displacement pump will work but their output for a serious leak is poor and a filter to keep out the usual -unavoidable bilge debris. A piece of dirt in these pumps finishes them.

It will not ever be able to pump dry as the water in the suction side will collapse back to the bilge when turned off. This is marginally better than the centrifugal submersables as they will collapse the output side as well.

This type of pump needs a much bigger place to locate and in your case this would mean that the pump will be further away needing a longer suction hose.

The positive displacement pumps do not appreciate bilge environment, where as it has no effect on the rule enclosed submersable types.

Is there no way you can fabricate a small sump? This would catch most of the water and even give it a chance to dry out. You could then get a more suitable pump.

 

Frosty,

You're right that the bilge configuration is the source of the problem. A small sump, if it were possible, would allow a small Rule type pump and make things simpler. Assuming the bilge can't be modified, though, I think the diaphragm pump is best. The rotary positive displacement pumps, like the existing Water Puppy, have the drawbacks you mentioned. A diaphragm pump, however, can pass small debris without any damage. A large and sharp piece of metal or glass could tear the diaphragm, but such an object would take out any pump. A diaphragm pump can be left running until the suction hose is almost empty, so there will be less water to run back.

For emergency use, you're right again; it would be a good idea to install a 2nd pump, a much larger Rule type pump, maybe as big as the 3700 gph model. They are relatively small and inexpensive for their capacity (even though it's less than advertised), and it would only be used if something bad happened and the diaphragm pump was being overwhelmed.