Bilge Pump Check Valves

[LADYBUG TOO]

Ladybug, Too has two bilge pumps with the forward pump having no check valve and the aft having a check valve. Anyone have an opinion as to whether the check valves are necessary. Ours seems to clog or hang up and I am about to take its guts out and chunk 'em. Of course, my first "gut" feeling isn't always the right thing to do. Things are done for a reason so maybe I can be enlightened by a fellow Tugnut.

Pat & Carolyn, Ladybug, Too

 

[knotflying]

You really need the check valve on the lower one because the water in the hose will come back down when the pump goes off and then the sensor will activate the pump again from the water that just came down the hose. Kind of like a circular reference error you get in excel when your formula results has no end. You don't need it in the higher pump because that wont be affected by water backing down into the bilge and is really only used in the event that the lower pump fails or you are getting way too much water in the bilge. The short answer is get a new check valve.

 

[LADYBUG TOO]

Thanks!

I plan to remove it and inspect it while the boat is still on the trailer. These Northwest winds are keeping us from launching as the tide and wind combine to dry the launch site.

Pat & Carolyn, Ladybug, Too

 

[Jake]

I once read that proper install is no check valve with a loop in the hose. The loop would need to be located in such a spot as to prevent an excess of water backflowing into the bilge.

Jake

 

[knotflying]

The loop would have to be higher than the thru hull so as to allow the water on the hull side of the loop to drain. I think that with the size and depth of our hull you may not be able to accomplish an effective setup.

 

[Todd]

With the pump lower than the outlet, and no check valve the contents of the hose will siphon back to the bilge.

The loop only helps to prevent seawater that sloshes up against the side of the boat from entering the bilge. Especially important in sailboats the tend to lean over a bit lowering the thru-hull.

Not saying you definitely need a check valve as the amount of water in the hose would probably not raise the bilge level enough to activate the pump but you will have more water in the bilge and the pump will cycle more often.

 

[Jake]

The loop would have to be higher than the thru hull so as to allow the water on the hull side of the loop to drain. I think that with the size and depth of our hull you may not be able to accomplish an effective setup.

Not sure if I follow (certainly wouldn't be a first 🙂 ). The pump pushes the water out thru the hull whether you have a straight run or a loop. Seems like the only difference is that with a loop you would have water stay in the loop as a "seal" as in a trap in a sink drain.

Jake

 

[knotflying]

Yes, but it would have to be higher than the thru hull so that the water on the lower end will drain out of the thru hull, but it will also drain back to the bilge pump. If you use your sink example the water drains out of the sink through the trap and down the drain. The water stays in the trap because water seeks it's level and will not drain from the trap. The trap is there to seal the pipe, thereby eliminating sewer gas from entering the room. So, if your loop is below the thru hull the water on the thru hull side will still run down hill and go back to the bilge pump and the only remaining water staying in the loop is that that seeks its own level, but the water on the downhill side will still run out to the bilge pump.
The reason for a loop on a thru hull is to prevent water from backing up the thru hull and past the loop. Take a look, I bet you most of the loops are directly behind the thru hull.
Hey without thinking too much about it, don't you think if Ranger could save having to buy a backflow preventer by making a loop they would have done that?

 

[nzfisher]

Once a year I run 5 gallons of hot soapy water through the bilge. This serves to both verify that the bilge pump is working and seems to clear some of the accumulated gunk that causes the check valve to stick. I assume that what is going on is the bath tub ring of viscous oil on the sides of the bilge walls gets sucked through the pump keeping the valve from opening properly. The soapy water seems to clear it out after a couple or 3 gallons.

 

[LADYBUG TOO]

Ladybug, Too does have two loops above the thru hull for the discharge lines. We did some rerouting when we removed the generator to repair the generator platform. During assembly the factory has to tie things down to make sure they don't get pinched when the cabin top is fitted to the hull. We isolated control cables, power, water supply and flush pump lines while we could get to them. There is still a lot of "spaghetti" going fore and aft but at least it is deciphered. Anyway, even with the loop the forward bilge line without the check valve does flow back when the pump shuts off. I can see that the loops are effective in keeping "sea wash" from entering the bilge. We would have to really get smacked to take on water through the loops. While I am not comfortable getting "in the trough" I am amazed at how well the tug takes a bad day in the Gulf.

Pat & Carolyn, Ladybug, Too

 

[Levitation]

Ranger Tug builds a nice boat - and their sales reflect that.
However, in a quest to hold down the cost they take some shortcuts which do not meet ABYC guidelines.
Their thruhull plumbing is one.

A loop of hose/pipe to act as a siphon breaker works (mostly). All bilge pumps should have a check valve right at the pump output to block drain back along with the siphon breaker loop in case the check valve sticks open.

 

[Andrew Custis]

Hello Dennis,

Thanks for the feedback. We really appreciate it. One thing that many people don't realize is ABYC is actually a "guideline" and not a rule. I am ABYC certified in systems and agree that MOST of their practice is a good one to follow. As a boat builder ABYC is not required to build boats. However, today, all of our boats we build are backed by NMMA which follows all of the standards ABYC does and more. It's required for us to send product overseas so we thought we would keep this practice on all of our boats. We have certainly improved over the years and most of that growth is directly related to the feedback we get from our customers so I thank you for that.

Take care,

Andrew Custis

 

[Andrew Custis]

One other thing to add. All bilge pumps should not have a check valve. The only reason a check valve is installed in our aft pump is because the keel is too small to handle the amount of water that comes back in once the bilge shuts down. Without a check valve in the aft pump on our boats, it will cycle. If it was me, I would do everything to not install check valves just as Ladybug mentions but you really don't have a choice. On all current models, we have a loop in the hose at each bilge exit.