Check yer bilge pumps!

I was mucking about in the engine room, replacing the gaskets on my Graco raw water filter basket. I threw a bucket of water in the bilge. Bilge pump came on but no water came out. After mucking about found that the check valve was stuck. So check your bilge pumps to ensure they are working according to specs.


Jim
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That's why check valves are not recommended on bilge pumps

So I wondered about that. Clearly there are pros and cons. You don't want water entering the bilge from a through hull if you are rolling around in the trough, but then there is the stuck check valve issue. What are the ABYC guidelines on them?

Jim
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No check valves...too much restriction on pumps that can barely handle head without a significant reduction in performance. Not to say one small one with a check valve to keep the bilge relatively dry is a crime if there is plenty more pumping capacity.


Vented loops or just a high enough above the waterline discharge so a loop isn't necessary.

I concur with Scott, our whale gulper has a built in check valve sort flap so we don't need it. I would remove the check and add a loop lie, said above. What kind of bilge pump is it?

JDCAVE said:

So I wondered about that. Clearly there are pros and cons. You don't want water entering the bilge from a through hull if you are rolling around in the trough, but then there is the stuck check valve issue. What are the ABYC guidelines on them?

Jim
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Click to expand...

Digging further, this article, page 6 para 4, by Steve D'Antonio:

http://rjwsurvey.com/uploads/Plumbing_the_Depths.pdf

"Note that a check valve is not considered an anti-siphon device and is expressly prohibited for this use under ABYC standards."

Sounds like it should be removed. Sorry, I was writing this as you guys were replying. Thanks, as always for your feedback.

Jim
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This article emphasizes the need for a riser loop.

http://www.yachtsurvey.com/bilge_pumps.htm

"For power boats, I recommend a riser loop height of about 18" above the water line. For sailboats, you have to consider the heel angle of the hull, which means that it will probably be tapped into the cockpit scuppers or sink drain. Here you have to be real careful of judging the water line right. "


Jim
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Its more difficult to keep a dry bilge without a check valve, but I'd rather have a bit of water down there than the potential for a LOT of water.


Besides the check valve sticking, bilge pumps often fail due getting gummed up with everything that makes it way down to thee bottom of the bilge. Bits of wire, hair, pistachio shells, fuel filter o-rings, etc.


It's worth pulling them out on a regular basis to remove the shroud around the pump drive blade, and cleaning all the gunk than collects in there. They may still operate when gummed up, but capacity is greatly decreased.


Another check worth doing occasionally, is allowing full flow from your main raw water inlet thru-hull to flow into your bilge. See how well your main bilge pump keeps up.

I had one of my two Johnson2000 units (the orange ones) turn on but not pump water The 800 gph SeaSense is the one that does the work and the two bigger ones are tested on the 1st of each month.

Usual testing is to click them On (Auto/Off/On switch) and then back to automatic. Next, I lift the float switches. Well, all was fine so I thought.

Then when they pulled the V8 there was water in the bilge. One pump although it was running did not pump water. It was past it's guarantee date so was replaced. I'd never tested to see if it would pump though the motor ran fine. The suggestion to flood the bilge with raw water is a good one except my raw water is above the waterline (barely!)

Now when I fill the water tank with the hose I flood the bilges with fresh water and make sure both big pumps will actually vacate the water.

Side note on Johnson's: the guarantee is now five years. It was three. Mine was six years old when it croaked though it had never pumped anything in all that time. Maybe I should have gotten it wet or sprayed the impeller?

Any thoughts on that for those high water pumps? Should I spray the ones that are never wet with something?

Correcting the problem on the KK42 can be difficult. The sump within the bilge is just big enough to contain the pump and a float. With out a check valve, the water in the hose with or with out a loop, when the pump shuts off, runs back into the sump causing the pump to turn on again. I've tried different size pumps, different switches and I reinstalled a check valve. It's not right but it's something I've learned to live with.

The 18" loop that was mentioned isn't practical since the salon floor is less than that above the water line.

Larry M said:

...

The 18" loop that was mentioned isn't practical since the salon floor is less than that above the water line.

Click to expand...

In my KK54 the loop for the ER bilge pump goes up behind a panel in one of the cabinets in the saloon.

Richard
Stillwater
KK54 #5

Thanks Larry. I was trying to figure out how to do that myself. My check valve is bronze. Should it be replace with another material?

Richard, I'm not sure that might be practical in my situation as there is no cabinet directly above the through hull.


Jim
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for deep sumps, deep in the bilge...try one of these....no check valve necessary.


They aren't very high volume though.


With a bronze strainer next to the float instead of the pump itself...it will pump all but an inch or so out of the sump.


Jabsco 36600 Series Diaphragm Bilge Pump

Hi All - Great Thread!

I post here to get in the loop. Will review posted links soon as time permits.

Art

psneeld said:

for deep sumps, deep in the bilge...try one of these....no check valve necessary.


They aren't very high volume though.


With a bronze strainer next to the float instead of the pump itself...it will pump all but an inch or so out of the sump.


Jabsco 36600 Series Diaphragm Bilge Pump

Click to expand...

Thanks. I'll take a look at more when we get back to JAX.

You're right about the low flow at 8GPM and 3/4" hose. But it may take care of the check valve issue and the low flow would be ok if there is a second, larger capacity pump for a back up.

"You don't want water entering the bilge from a through hull if you are rolling around in the trough,"

A riser loop requires the SAME amount of power to lift the water to that height as simply discharging the water out of a thru hull at that height,

KISS!

Check valves and a bilge pump=NO.


Not on my boat, If that means a bit of water in the bilge, well so be it.

I agree no check-valves in bilge pump line, but if the thruhull is well above the waterline, why would you need and anti syphon loop at all..?

You have to define "the water line" at the maximum heel of the boat. I fully agree on "no check valve".

I think the usual practice is to run a line into an area where the loop is high enough, such as a locker of behind interior liners, etc.

Sometimes it takes an absurdly long line.

I have seen rules of thumb for the height required to not require a loop....and many say 12 inches (which for many coastal power boats would probably be enough unless you love rough seas).

The "max heel" is usually geared for sailboats, but without a loop with siphon break there is always a chance of siphon induced flooding.

psneeld said:

I think the usual practice is to run a line into an area where the loop is high enough, such as a locker of behind interior liners, etc.

Sometimes it takes an absurdly long line.

I have seen rules of thumb for the height required to not require a loop....and many say 12 inches (which for many coastal power boats would probably be enough unless you love rough seas).

The "max heel" is usually geared for sailboats, but without a loop with siphon break there is always a chance of siphon induced flooding.

Click to expand...

I do love handling a good boat in rough seas. Been a long time since. Always wanted to try it full-tilt-bogie by piloting one of the USCG search and rescue "rollover" vessels. What a gas it would be to have control of a boat that virtually could not be broken... sans getting too close to and in contact with shoals/rocks. Jus sayen!!

Any boat can get broken and people hurt.

Nice if it's not your boat, not your responsibility and there's rescue resources standing by.

Not too many opportunities for all that.

Most of our boats aren't made for continued use or comfort in seas that keep burying thru hulls mounted well above the waterline.

Art: Having trained at what is arguably the roughest bar in North America (Cape Disappointment, Columbia River Bar) on a USCG 44' mlb, self righting, self bailing, I can certainly tell you it is a RUSH! Of course "full bogie" in a 44 is about 12 kts, when you're crossing the ever changing bar, with the 9 kt current of the Columbia fighting against an incoming tide, the feeling can't be beat and I'll be forever thankful that I had the opportunity to do it multiple times.......that being said, I really don't ever want to try it in MY boat except in the calmest weather lol. But, back then in the CG the motto was "You have to go out, you don't have to come back." According to my son who is currently in the CG, that has been changed and they do a danger/likelihood of rescue assessment before they commit. Hmmmmm.

Peter B said:

I agree no check-valves in bilge pump line, but if the thruhull is well above the waterline, why would you need and anti syphon loop at all..?

Click to expand...

Larry (post #10) defines our particular problem quite well: the pump will cycle on and off as the water in the line goes back into the small bilge if we use the vented loop solution. A smaller secondary pump with a narrow line might work but the bilge would be very crowded. I'm not sure there is room. Larry: Thoughts?


Jim
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See post 13, that type of pump should eliminate drain back...but hardly adds to emergency pumping capacity.

There are also tiny micro pump systems to keep bilges very dry.

JDCAVE said:

Larry (post #10) defines our particular problem quite well: the pump will cycle on and off as the water in the line goes back into the small bilge if we use the vented loop solution. A smaller secondary pump with a narrow line might work but the bilge would be very crowded. I'm not sure there is room. Larry: Thoughts?


Jim
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Click to expand...

Have you looked at the turn on / turn off height differentiation of various switches? And some are much more prone to getting re-triggered by wash back than others. I had this issue in my aft bilge as well as in a heavily used shower sump; I installed Ultra Pumpswitches and voila the problem was gone.

One could easily create a shop vac based bilge emptier if you wanted to keep it really dry. Another method is have a blower hose aiming there and evaporate faster than the drips. I was able to keep a 1952 Chris craft cruiser bilge dry with a blower fan sometimes.

I use one of the Jabsco diaphragm pumps PSNeeld suggested. I don't have a deep bilge like your KK but i,'ll bet it would do the job .
The pump itself can be mounted elsewhere with only the hose and a bronze hose end mount strainer dropped into the water. These pumps will suck the water, priming easily, and are able to lift the water a good distance. Little runback, only that water which is in the suction side hose. The remaining water will not run back like a centrifugal.
As mentioned they are are not intended for flooding control but will do a good job, or should do, of dewatering normal bilge water accumulation.