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[email protected] fred.gerbstadt@verizon.net is offline
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First recorded activity by BoatBanter: Dec 2006
Posts: 1
Default Shower drain plumbing design

I built a 39 foot FG sailboat about 20 years ago. The shower drain
plumbing (almost) never gave me a problem. Let me describe it.
Perhaps you can fit your boat similarly.

The shower (and two sinks) drained by gravity into a 6 gallon sump tank
located in the bilge below all drains. The sump was emptied by a small
pump. The pump discharge hose was lead up to form an anit-siphon loop
well above the (heeled) water line then over board via a sea cock that
was located in the center of the stern above the waterline. Being on
the center the exit was (almost) always above the water even when
heeled. The anti-siphon break in the loop is needed to prevent
possible back siphoning into the sump tank. Of course, when the pump
emptied the tank it cavitated and the pump was shut down by a manual
switch. Water would then drain from the loop and return harmlessly to
the sump tank. Voila!

Hair is always a problem with pumps. My wife and I were careful after
showering to wipe hair from the strainer and dump in the garbage (in
port) or into the head (at sea). Periodically (like every three months
while living aboard), the pump would have to be removed from the sump
tank and de-haired --- yuck!

BTW this scheme allowed me to have only three thru-hulls below the
waterline: engine input, head input, and head output.