So I am getting water into the bilge from the thru hull fitting for my bilge pump exit. The exit is close to the water line so sometimes water just rolls down through the pump into the bilge.

It is not a lot but I am trying to decide if I should solve it. I have heard that adding a check valve could be a big no no cause if it fails and water can not pump out then it sinks.

Anyone have any thoughts, do you use a check valve or did you solve it another way?

If you add a check valve, you have to be careful about hose routing. You can create an air lock that the pump can't clear. You need to keep the hose rising all the way to the top, with no flat or low spots. Also, you need to be sure that your check valve's cracking pressure is low enough for your pump to overcome. Johnson pumps come with a check valve, and it may be that having it built in like that helps the air lock issue. I always run the hose up well above the water line and then back down to the outlet.

another fix is to route the hose 1' or so above the waterline before it connects to the thru hull.

i made a little breathing rig to change props in the water on my shaft boat. the valves i used from Lowes are i think for septic tank lines. they are rubber flapper like a purge valve in a facemask for diving. but a loop attached to transom that goes up even just a couple inches above thru-hull would do the trick.

Plug, how did you solve this?

I routed the hose up and made a loop. I decided not to do the check valve idea. It seems to be working.

+1

I dont think I have enough slack in my tube to make a loop. Will have to check it out.

I didnt have much slack or height to add a loop. Mine was running straight, then angled down the to the bilge. So it was almost creating a siphon if any water did get in. I just routed mine in a small hump as high as I could, ziptied it and then ran it down. I did the best I could and it seems to be helping.

I have a loop in mine.