Plumbing a 2d Bilge Pump
I'm adding an electric bilge pump that will sit above the intake hose for the existing manual bilge pump. To avoid cutting another through-hull hole, I'll run the new hose to a Y connection downstream of the outlet of the manual pump.
Q: Will bilgewater from the new electric pump flow backwards into the Y, through the manual pump, and into the bilge? The existing manual pump appears to be a Whale Gusher Urchin or similar.
I could install a non-return valve upstream of the Y connection, but advice that I've seen recommends against that, because it'd (1) restrict the outflow and (2) possibly jam.