Greetings, I have read the full forum subject on this as well the full blog of the owner.
In review. There is much mention regarding the bilge pump in question located in the engine pod to which I would like to contribute. I will by the use of my personal incident with a Rule pump, (same manufacture).
In my case, on odd times there would be a substantial amount of water in the bilge without any apparent source. I would taste the bilge to confirm it being salt water after thinking that the source was a leaking hot water tank, not the case.
The bilge would be pumped and watched with no incoming water found. There would be days between with no issue. Then a voyage would be made and during that time checking the bilge, water would again be found. Of course, a complete search of the bilge an all, I repeat, all connections to the three Rule bilge pumps would be accomplished. with all connections tight.
After being at anchor one night, with guest aboard, checking for engine start up, I noticed a larger amount of water than even that found in earlier finds. This made the issue too serious to not find the answer.
BINGO!!! It came to me, the overboard outlet for the bilge pump was AT WATER LINE level. hence, with the extra folks onboard, the weight allowed the bilge pump discharge to be under water here is the find (THE RULE BILGE PUMP DOES NOT HAVE A CHECK VALVE BUILT INTO IT.) I found later that only recently had Rule redesigned pumps to include some sort of check ball, not in any of the existing pumps on board my boat.
I reinstalled the discharge hose with new that formed a hoop loop above the discharge and the issue was cured.
Having said this, if you review the photos of the engine pod and the bilge pump discharge, you will note that it comes in at or below the water line and is a direct drop to the pump.
What I am saying is with the water being forced up and about with the stern facing the waves, the water was coming in via the bilge pump and not the stern gaskets resulting in filling the pod. At some point as the boat was becoming laden, the inflow was increasing allowing faster flow backwards through the discharge hose to the and through the bilge pump itself. (No Check valve)
Al-Ketchikan.