Small diaphram pump to deal with bilge pump backflow?

[DougMc]

Greetings,

Our Oceanis 45 has a rather small bilge sump which contains the automatic electric bilge pump, plus the pickup for the manual bilge pump.

The bilge pump (Rule Mate 1100 automatic) contains a check valve which, in principle, prevents the water in the (rather long) discharge hose from flowing back to the sump, so triggering the pump to run again.

In practice, the check valve is never completely perfect and so the pump does cycle with a period that depends on how well, or poorly, the check valve happens to be sealing that day.

I can switch off the pump, let the sump fill, empty by hand, and then switch the pump back on to "auto", but I'd prefer that to be taken care of automatically. I gather this is a fairly common problem.

There are a few diaphragm pumps out there that would probably to the job, (Rule RD412, or Whale gulper 320 or 220) but they seem like overkill and may be a little on the large side to find a practical place to install.

Ideally, I'd like a small diaphragm pump with a small electronic water sensor that could be installed low in this bilge sump. Then, I could plumb that into an existing sink drain, etc.

Can anyone point me in the right direction for options or, ideally, a system that does this job without too much overkill?

Absent that, any pointers for a compact, reliable water sensor/switch would be appreciated and I'll figure out a home-brew solution.

Thanks,
Doug

[wyb2]

We just used one of these cheap little pumps from ebay/amazon. No automatic switch (had those on 2 bilge pumps). Left the pvc tubing permanently installed (well, with zip ties, so not super permanent), routed from the bilge to the sink, with a split in the middle to plug the pump in. Wired a cigarette style plug to the pump.

https://a.co/d/1bQfb3F

Process was to grab the pump out of the drawer, pull the tubes (at the split) out from the hatch they hid behind, plug the tubes into the pump, plug the pump into 12v, then grab the loose end of tube down in the bilge and use it to suck any remaining water from the corners of the bilge.

I never tired to make it automatic because the issue was the 8-12 oz of water that would hide in various corners, so you would have to be there to move the intake around either way.

[Cheechako]

It's a common problem and Jabsco rubber diaphragm pumps have been used often to get the bilge dry. They mount outside the bilge which helps to alleviate and flow back. Unfortunately the good ones are expensive, even though they dont pump a lot of water. They are usually activated with a float switch in the bilge, but manual may be the best way as you can suck nearly dry any time you want.
https://www.amazon.com/12V-Light-Dut...19180628&psc=1

[Calif.Ted]

When I clicked on Cheechako's link it opened to tell me I last purchased that pump in 2018, so that's exactly what I've used on my boat in a remote location with a float switch in bilge. Float switches come on at 3" and off at 3/4" so manual needed for remainder.

[Uncle Bob]

There is a product available called dry bilge (I think) that runs periodically to completely remove residual water, runs on a timer so no float switch, a small diaphragm pump and an intake filter. Expensive for what it is but there are descriptions on how to make your own using readily available materials for much less.

[sailingharry]

I have used the pump that Wyb2 referenced. Ultra cheap and worked well, but only for a few months. It does self prime.

I have used the $15 Amazon diaphragm pumps that look like a miniature surflow pressure water pump. They last about one day before they clog up. The valves can't take anything, I think they clogged on dust. I could take them apart, clean them, put it back together, and it would last about another day.

The pump suggested by cheechako would be extremely reliable, but huge, expensive, and massive overkill for one to two gallons of nuisance water.

Also on Amazon is a submersible centrifugal pump. While It suffers from the same flow back of a bilge pump, it is small enough that the suction could be in less than half an inch of water, and the flow back in a quarter inch line would be pretty small. I haven't tried one yet.

Those of us with keel stepped masts will never have a dry bilge. It sure would be nice to have a way to get it dry after a rain event!

[OldGreyB]

Some ideas:

Electronic bilge switch and / or bilge monitor: https://waterwitchinc.com/

DYI dry bilge : https://panbo.com/a-dry-bilge-for-50/ and / or version here: https://raider33.com/2022/10/25/adde...-bilge-system/ ( uses a Seaflo© diaphragm pump) . Could probably use these ideas, but with a small diaphragm pump such as posted by wyb2 and an inline filter.



Commercial dry bilge: https://www.seaflousa.com/product/se...-bilge-system/

[capt jgw]

I had the same probably and fixed it by adding a second small pump with it's own float switch. The discharge hose was routed to be as short as possible. I also raised the float for the larger pump about 2 inches so it only comes on if the small pump can't keep up. That's never happened. The small pump only back flows a few ounces, not enough to cycle the pump back on.

[Bellinghamster]

I have a little 12v peristaltic pump I plan to use to bail out the little (~1/2 quart) sump under my propeller shaft stuffing box to prevent it from overflowing into the deep (normally dry) bilge under the engine. I haven't settled on how to switch it yet. Probably a liquid level reed switch that turns on a mosfet or little DC relay to run the pump motor, maybe on a timer.
A couple links for reference (not the sufff I'm using, but should communicate the concept)
https://www.amazon.com/Peristaltic-L.../dp/B075VN1QZM
https://www.amazon.com/Liquid-Level-.../dp/B09VCZS3D2
https://www.amazon.com/Sipytoph-Chan...sp_product_dpx

[sailingunity]

We have a diaphragm pump as our main bilge pump. A hose runs down into the bilge and the pump is mounted remotely. A remote switch turns it on.

[Mickeyrouse]

My complaint with the Rule-type pumps is you can’t protect the pump from bilge crapola. I have used the Par/Jabsco pumps with a float switch and check valve for many years. A water strainer is essential- you would be shocked to find what can find its way to the pump.

[wrwakefield]

We use the purpose built Whale IC bilge pumps for bilge maintenance [vs. emergency pumping.]

You can mount the pump up out of the bilge, and their solid state water sensor is quite tollerant of the usual bilge muck.

Raise your existing pump a few inches above the Whale pick-up to become the back-up/emergency bilge pump.

Our approach may not suit everyone's needs.

Cheers, Bill

[s/v Jedi]

Use one of those mini shop vacs. You can make a semi permanent install.

[DougMc]

Thanks for all the suggestions.

I've ordered parts to experiment with a home-brew system based on the small seaflo pump and the waterwitch switch. I won't be back at the boat for a few weeks, so I'll have time to play around and try to figure out any unexpected quirks.

cheers
Doug

[NorthCoastJoe]

I second the shop vac. A sponge and bucket if you want to have it dry.