One other question on bilge pumps, ours runs about 12 inches to a check valve, then T's with the shower waste before being sent overboard. I have noticed when we use the showers (both sides) a small amount of water flows back through the check valve and into the bilge (maybe 1 litre per shower) Is that normal, or should check valves stop ALL water returning? I don't like the system as I prefer keep the bilges bone dry so I can monitor for any leaks. This system is ensuring there will always be some water in the bilge and the bilge pump will have to run occasionally to clear some of that water. The keels have been filled with a small sump space left for the bilge pump which holds approximately 10l of water. The most the pump can evacuate is about 9 litres, leaving a 1cm deep puddle in the sump.
Absolutely no shower water should drain into the bilge. This will ensure over time that the pump will get jammed with hair and soapy skuz and stop working. Maybe just as you need it. It will also start to smell. Cleaning
up that last bit of water is always a bear. A good sponge or a small suction hand pump or turkey
baster will work. Then keep your bilge dry.
Relying on check valves when you are dealing with soapy water with grease and hair is like putting your thumb in the leaking dike. Might work for a little while but it is folly. I would complain loudly to Lagoon
if I were you. You really need two separate through hull
fittings with proper vented loops.