Postby SplashyLady » April 28th, 2020, 10:58 am
Shower drain pumped into a thru-hull secock under the water line? This is only OK if there is a vacuum break on the outlet line (can't see one in the picture). There should also be a plastic or stainless "hair filter" to protect the pump from gumming up with hair and shower debris. Waste pumps are good at pumping lots of "stuff" - but hair is a special challenge and can clog the check valve or duckbills, allowing them leak back.
Old boats used to do something like this - with a cover over it or a closed tank and pump the shower drain and sewage/toilet waste overboard. Discharge of human waste has been outlawed for a long time now for inland and coastal waters. Gray water, like the shower, is another story. No federal rules prohibiting gray water discharge in the US, but Canada, some US states, and some lakes and marinas have rules about gray water discharge.
Most drains and pump outlets discharge above the water line. Unless there is a proper vacuum break, if the check valve/duckbill on the pump leaks back, the pump will cycle continuously or fail, filling up and overflowing the open-top box. Like a bilge pump, usually the most unreliable part is the float switch. My advice would be to replace this "box" with a proper shower sump (with a top) and run the outlet from the pump to the side of the hull above the water line, same as an A/C outlet or or bilge pump. This assumes gray water discharge is OK at your location. If you have a proper vacuum break, you are OK as-is, but still may want to change the outlet from the existing pump to be above the water line and close the seacock to prevent any chance of backflow. Put the new outlet on the side of the hull at least 1 foot above the water line.
Hope this helps - good luck!
Captain John
Past Commodore, Peninsula Yacht Club
Lake Norman, NC
Carver 3227 - "Splashy Lady"
Aquasport 222CCP - "Gone Fission"