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Ericson 38-- Bilge Pump Systems and Considerations

Rating: 19 votes, 5.00 average.
What are bilge pumps for?

I admit that for the first half of my life I figured they were there to keep the boat from sinking. But of course, they won't. Not even the manual Whale diaphragm that came with the boat will do that. Surely not the buzzy little gizmo under the floorboards that spits out of the transom.

A Rule 1500 centrifugal bilge pump is rated at 1500 gallons an hour, or 750 2-gallon buckets. Sounds powerful. It would take a strong crewman to match that, not to mention 750 buckets. But in the real world, well, 1500 gallons an hour is not likely. We need only look at the stream of water our bilge pumps put out to consider that that is the amount they can handle coming in. A big manual pump does better, but it's work. Fill the bilge with hose water and try it--we should do that periodically anyhow, with a bit of citrus cleaner. Twenty strokes awkwardly bent over and I'm ready for a rest.

So why do we feel such a sense of security with our little bilge pumps? I guess it lets us sleep at night in our beds far away: Seacocks closed, hatches locked, bilge pumps on standby, nighty-night. Sure, our pumps are adequate protection against a stuffing-box drip or a heavy rain with the hatches open. Which is fine, because our fiberglass boats don't leak below the waterline anyhow. A hull breach is another class of event entirely.

So if bilge pumps have a simple job, let's try to get them to do it, which they so often don't.

--Empty the bilge. Too much to ask?
--Function when needed . Too much to ask?
--Not wear out every 18 months. Too much to ask?

Yes, probably. In any case, here are the changes I made to the new boat, and the reasons why:

Diaphragm not Centrifugal Pump

The electric submersible bilge pumps I have had, and which the new boat had too, are not self-priming.

Old system

They need bilge water to work, and if the bilge ever goes dry, they won't. They are famous for whining happily and making tiny bubbles while moving no water at all, which can be surprisingly difficult to tell if the bilge happens to be slopping around. But who wants standing water in his boat? So a one-way valve is often inserted in the line. This keeps the water in the hose from running back into the bilge. If it works, of course, the pump loses its prime. Informed opinion states (I'm citing Maine Sail, among others) that a one-way valve in a bilge line is a terrible idea.

I believe it. It was a one-way valve that caused me unnecessary worry offshore (Why is the pump running but the water not going down. Am I sinking?). The current boat came with two such check valves, one for the main bilge and one for the shower bilge. The main bilge valve worked too well--the pump wouldn't run unless the bilge got half full. The shower bilge valve was clogged closed with human hair, permitted no bilge water at all to pass, and had been that way for years.

However, cutting out the one-way valves presents a problem. Many bilge hoses have no anti-siphon loop, and no vent either. Apparently not required, and not tradition. So a one-way valve keeps the bilge pump from siphoning water in on some points of sail.

I tried to add an anti-siphon loop and vent to my bilge hoses. No room back there on this boat. Forgetaboutit. So, how to resolve these conflicts?

Many E38s, and other models, came from the factory with diaphragm bilge pumps located in the engine compartment. Mine was removed long ago and replaced with centrifugal submersibles wired to automatic float switches. None of that fit very well between the keel bolts. Perhaps the change was made because centrifugal pumps do move more water than an equivalent diaphragm pump. But then you need a check valve.

Diaphragm pumps don't need in-line one-way valves, because the pump itself contains two. There is no run-back. There is no siphon possibility. They move less water, but they can suck it all out because the pump is not submerged, doesn't require a prime to operate, and can run dry without harm to itself.

I chose the Jabsco 3720 Light Duty diaphragm pump with a suction lift of 7 feet and 3/4-inch ports. After some head-scratching, I mounted it in a seat locker, rather than the engine compartment. Diaphragm pumps are sensitive to particles, so a separate pre-strainer is required.

New system

To provide automatic operation, I ordered the familiar Rule Three-way panel switch. I like it mounted here, under the protection of the saloon table, because if I happen to be manually activating a bilge pump, I am also likely looking at the bilge water.

Instead of a traditional float switch, I went with a newfangled electronic sensor, the Water Witch #101. The Water Witch fits more easily in our bolt-challenged TAFG bilge.

I left the shower sump rigged with its tiny Rule pump, ancient two-pronged water sensor and factory-installed three-way switch. I installed a new one-way valve, and shrugged. We won't be using the shower much, and nothing else drains into that bilge.

The new system seems to work fine. The diaphragm pump hose gets all but a quarter inch of water out. Kind of a joke, though, since depending on trim the lowest bilge can be any of three compartments. The old pumps were, as is typical, a maze of hacked wires, tape and cable ties, and the hoses were stained and tired. The new installation looks neat and clean, with all bilges painted Brightside white. The diaphragm installation is hidden under a seat locker insert that protects the wire runs there and expands the usable space.

This was a theoretically easy Saturday-morning job that wound up taking two weeks, three orders of gear from Defender, and upwards of $300 including a low pass by an actual boat electrician.

None of it will stop us from sinking. But it does mean a good night's sleep.

Added: Modification to drain remote compartments:

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  1. Loren Beach's Avatar
    In two decades, I have replaced one of the expensive Jabsco chamber pumps and relocated it for better access. New strum boxes. Currently I am in the final lap on the renovation of the Gusher 10 on the cockpit combing. New hose run, & I relieved a lot of pressure points in subterranean passage holes with the die grinder, and secured all parts of the hose against movement.
    Previously I replaced the hose runs for both electric bilge pumps and secured a loop up high in the laz. to stop any potential back flow.
    I do realize that the purpose the "Category one" pump that Ericson installed was just to gain time.
    That's why the offshore racing rules required that it be operable from the helm. i.e. the driver is pumping while tending the helm and the crew is finding/staunching the leak(s).

    Funny thing is, it's hard to be sure from where the water may appear! I know a boat that took in a lot of gallons during a local offshore race. One of the crew found water over the sole in the middle of the night and it took some quick and excited work with flashlights to find that a change in the head plumbing made by that same owner had come adrift and was letting water in through a large hose. "Operator Error, indeed!"

    Over the decades we have all tagged crab pot floats off the WA coast and one trip the boat I was on was towed in when the shaft was locked up by a float/rope. (No wind and water waaaaay too cold to leap into.)

    Another boat from my little YC was hit by a leaping whale a few years ago. They motored back in to Astoria and their insurer later totaled the boat.

    I worry about metal shipping containers, but there are also quite a few other threats out there, percentage-wise...

  2. Bolo's Avatar
    Christian: Very good posting! It has inspired me to replace the pump on our 32-3 for a number of reasons but mostly because the centrifugal pump always leaves about and inch or so of water in the bilge because I removed the one-way valve years ago because I just didn't trust it. I do have on in the shower bilge but left that for the same reasons you stated. I was thinking of placing the Jabsco 3720 Light Duty diaphragm pump in the aft port locker, close to the point where the bilge water comes out of the boat. Since you had a 32 I was wondering what your opinion would be for installing it there. Of course, the reasons why water gets into the bilge in the first place are many and the one I have needs to be addressed. I think I'm getting water in through the set of hoses that drain the inner scuppers and end up going out of the boat through the sea cock under the galley sink. I did replace all of the hoses which were full of holes but still water gets out, someplace...I just haven't been able to trace it down yet. I also get a fair amount of water in the shower/mast bilge but that because my mast boot is shot and will be replaced soon.
  3. Christian Williams's Avatar
    I also puzzled over where to put the diaphragm pump. I concluded it doesn't matter, as long as the pump won't be submerged (or wet), and as near to existing bilge hoses and the battery as practical. Easy access is good, because they do go bad or get clogged.

    Not much we can do about rain water, which comes down inside the mast so no boot can stop it. Also, on your 32-3, you're probably aware of the rudder post packing gland ( ).
    Updated 07-06-2016 at 01:16 PM by Christian Williams (add link)
  4. Bolo's Avatar
    Yes, I thought about access for repairs in the aft locker and that may be a bit of a pain since it would be mounted low. I may position it near the rudder post / water heater area that is easier to get to via the side engine access panel in that quarter berth. I do know about the rudder post packing gland but I'm fairly sure it's something in the inner scupper cockpit drains. When I close the seacock for those drains the hoses fill up with rain water and then it seems that the bilge then takes some water in over time. Leave the seacock open and no water at all. So I'm guessing it's a very small leak that only happens when the hoses are full. Hope you're having fun with the new "old" boat. We still get compliments on how nice our boat looks to other sailors. Still surprises us sometimes but then when I look back at Vesper she does have great lines. Just order all my parts for the bilge re-fit on Defender. Oh! My mast boot is part of the problem when it rains. When I washed the boat last time my wife saw water coming in from areas just outside the mast. Another one for the list.
  5. Christian Williams's Avatar
    Modification to drain remote compartments:
  6. ddoles's Avatar

    I've got a similar bilge pump system in my E38-200 and am happy with the diaphragm pump. I had the same issue with fitting a traditional float switch between the keel bolts. I went with a pneumatic sensor switch, which I'm not happy with for several reasons. I looked into the electronic sensor, which looked like a great solution. The one concern I have is that I've read that the sensor will not work with pure water as it needs some level of salts in the water to create the electrochemical connection. If the primary (or only) source of water in the bilge is rain water through the mast, will that be too pure to properly trigger the switch. What has been your experience?

  7. Christian Williams's Avatar

    The winter of 2019 was very rainy here, and my mast is a regular funnel. But every time I came to the boat the bilge had been pumped to water-witch level. Not scientific, but did ease my mind.