Bilge Pump Discharge Hose

[Carpediem]

Source of the post https://www.wholesalemarine.com/content ... Manual.pdf

Here's a rule manual. It clearly states "no check valve"
It also shows the flow rate at various ft of head pressure. The flow is rated at zero ft of head. Not sure what a duck bill would add, but bet it cuts the flow at least in half.

Thanks for the reference. Ill need to check out the MM of the bilge pumps on my prior boat. Ill be replacing all of the pumps in the boat as I go about cleaning up the mechanicals. As far as I know every thing is original and has not had much TLC over the years. The prior owners were more 'sit on the boat' type rather than ' work on the boat' types. If it wasn't broken it wasn't a problem. I treat my boats like I do my airplanes, I like to replace critical items before they cause me a problem.
I'm going to look into the whalepumps shared by @g36 Thanks!

[tomschauer]

Just a side note. I rinse and clean my bilges two or three times a year. Unless something develops a leak, they are always totally dry the rest of the time.

[Carpediem]

Source of the post Just a side note. I rinse and clean my bilges two or three times a year. Unless something develops a leak, they are always totally dry the rest of the time.

When I first started poking around on the 506 I found that there was water in the bilge that had been there awhile and I figured out why during the survey. The aft sump pump is shot so the grey water was overflowing into the bilge. the boat was rarely used so it was not noticed by the owner since he did not do any of his own servicing. I vacuumed the bilges dry when on the hard for survey and bottom paint and splashed yesterday for the 20 mile run home. The bilges were dry when we arrived. We will see how dry they stay after we have our next storm.

[Viper]

I agree KM, and there's no way a regular bilge pump setup would keep your bilge dry. By their very design, they always leave some water in the bilge. At about 3/4" of water, it'll start sucking air and won't pump water anymore. So if after it pumps out the bilge dries out by evaporation or some manual method, that's one thing, but the pump won't do it on it's own.

Folks in cold/freezing climates also have to consider that there will always be water in a discharge line with a check valve in it. At winterizing time, you'd either have to put enough antifreeze in the bilge until the pump turned on, or disconnect the hose and force antifreeze through it, or displace the water from the outside through the discharge fitting so there's no water left in the hose over the winter. Not getting rid of the water in the line before winter layup will result in a split discharge line and cause the check valve to fail/split. We used to have to address this with older bellows bilge pumps, there's always water left in them so they had to be winterized properly or you'd be replacing them in the Spring.

Your best bet is to take measures to prevent water from getting in if you want a dry bilge at all times.

[Viper]

Carpediem, you kept me up last night I gave this some thought and realized we may be overlooking something, the original thought/assumption (mine anyway) you proposed was about installing what I thought would be a typical inline check valve somewhere along the length of the discharge line. While this is not a good idea for a few reasons we already mentioned, I should however also point out that there are pumps equipped with built in check valves. These would be an option if part of your mission is to prevent discharge water in the line from dumping back in to the bilge once the pump shuts off. These valves are usually located right at the discharge port which solves the air lock problem. These won't however remove all the water in the bilge for reasons mentioned above. One must also keep in mind that other caveats mentioned above. Here is an excerpt from Johnson Pump about that....

"....NOTE: The check valve supplied with your pump is used to prevent the backflow of water. The utilization of the check valve requires you to be
mindful of its functionality. The check valve material is made of Nitrile material to be used for water applications only. Also, the check valve will reduce the flow of the pump. If flow is critical to the application of the pump, it is recommended that the check valve not be used.
Also, when winterizing your boat, remove the check valve to avoid ice formation and/or degradation of the check valve"

As mentioned before, this won't affect you in CA but up north these must be winterized if the check valve option is used (it comes with a valve but you don't have to install it). I've had to replace a couple of these on a boat that had them new from factory because the owner didn't realize they had to be winterized. The ports split. Most guys don't bother installing the valves for this reason or remove them a couple of winterizings later because they simply add another step and one more thing to remember.

Here is the type of pump I'm referring to. This is the Johnson Pump version but there are other brands with the same discharge check valve option...
https://www.spxflow.com/johnson-pump-marine/products/heavy-duty-submersible-bilge-pumps/

Hope that helps

Chris, apologies for the course change here. Did you consider a path to solving your discharge replacement problem yet ?