One of the more interesting features on a boat is the sanitary system.  All sewage is collected into sanitary tanks, then disposed of when the tanks are full. The main sanitary tank has about a 900 gallon capacity and is located amidships, roughly.   It collects all sewage from the enlisted personnel and galley.  When sailing on the surface, it is a fairly easy procedure to dump the contents of the sanitary tank to the ocean.  The tank is opened to the sea and air pressure is applied to force the contents into the ocean; the tank is then sealed and the air pressure inside the tank is vented outboard; it's at this point that you want to be heading upwind.

While submerged, things get a little more interesting.   The procedure is pretty much the same as on the surface, except 1) the tank is not emptied completely; roughly 50 gallons are left inside so as not to send a bubble to the surface, and 2) the tank  must be vented inboard (for the same reason).  The vent is located (where else?) in the overhead of the mess area and although the air is vented through charcoal filters, the filters come no where being able to remove the stench from the vented air.  When is the best time to vent?   How about dinner time?   That happened a few times, either due to a perverse schedule or scheduler, probably the latter.  I believe that the origin of the term "pig-boat" must have come from this procedure. It sure takes your appetite away.

All of this lead to a "fun" type of prank.  If a person was standing the midnight to 4AM watch on a Saturday night and if the boat was in port and if the tide was going out during the hours of say, midnight to 2PM and if there were one or two new guys aboard and if they were out drinking and came back a bit under the weather (this always happened), then conditions were just right.  The guy on watch would blow the sanitary tank during an ebb tide following the same procedures as when the boat was on the surface, EXCEPT, instead of venting the tank completely, he would leave about five pounds of pressure inside the tank.  The unsuspecting victim would stagger aboard and use the head.  To flush the head, one had to reach down behind the toilet and push a lever, which operated a flapper valve and allowed the contents of the toilet to flow into the sanitary tank. The lever was just off the deck, forcing the operator's face and shoulders to be centered perfectly over the opening of the toilet and just inches away; a most diabolic design.  When the lever was pushed, the operator would likely be wearing the contents of the toilet  on his head, shoulders and uniform. If your sleep was interrupted during these hours, and you heard footsteps overhead with a great deal of cursing,  shouting and death threats, you knew what had happened.  It didn't take long for a person to learn to check the sanitary pressure valve before flushing.

Looks easy, huh?  

 The cleaning of the sanitary tanks was a scheduled maintenance procedure whenever the boat went into the shipyards.  Two guys, each wearing a 1940s style space suit would climb down into the tank and steam-clean the insides.  A real nasty job!   For several reasons this was called diving the sanitaries.   Piss off the COB and you were almost assured of this joy!

My friend, Ralph, and his nasty habit.

There was a shipmate of mine, a guy named Ralph.   Ralph was a great guy - friendly, easy-going - he'd give you the shirt off his back if you asked for it.   He was a lot of fun, but he had this one personality quirk that was a bit dangerous, both to himself and to those around him.   It seemed that he harbored a deep dislike for marines and surface-sailors, in that order and this hatred surfaced after he had ingested only a few beers.   If a group of his potential adversaries were close by and with no exchange of insults or anything like that, he would politely excuse himself from the crowd, walk over to a table full of marines (not just one or two marines, but a table full - five or six - the more the better).   He'd yell "Fuck you, Jarheads!" and in a matter of seconds he'd be on the deck and wind up in the brig.   A few weeks later the same thing would happen.  Given the same situation; he never learned.  I picked him up several times, the morning after, at the brig and drove him back to the base.   Except for a few bruises he was back to normal, easy-going, jovial, etc.   I could never figure it out but he must have had a death wish.  

Don Dresch