There's only ONE reliable "blowout preventer"...
And it's not a piece of equipment, it's YOUR attention span and something called "preventive maintenance:"
Check the vent thru-hull regularly..backflush the vent line every time you pump out and/or wash the boat. If you start to experience back pressure when pumping the toilet, STOP PUMPING till you find out what's causing it and cure it. A blocked vent will cause a pumpout to pull a vacuum that prevents more than a gallon or two from being pumped out...so NEVER just turn pumpout over to a dockhand and walk away...stick around and pay attention to how much is being pumped out. If you have a pumpout service that shows up when you aren't there, they aren't gonna pay attention to whether the tank is empty or not...they're just gonna quit when the pump quits. So it's up to YOU to pay attention to how much is left in the tank before you go out again.
However, SeaLand does offer something called the "Tank Saver" which saves tanks from those owners who don't have enough of an attention span to maintain the tank vent:
http://www.sealandtechnology.com/productpages.asp?pid=68 But, like your mom's pressure cooker, it only works in one direction, which actually makes it useless, really...'cuz it can't prevent the tank from becoming pressurized if you continue to use the toilet against increasing backpressure, "belching" etc :naughty:...so it won't prevent the poor soul who opens the deck pumpout cap from taking a sewage shower in the resulting "Old Faithful" geyser.


However, the spew WILL empty the tank without pumping it out ... which means you won't have to worry about pumpout suction, so actually you don't need the Tank Saver...just an attention span! :dance:
Nothing on a boat is maintenance free...and there's a very good reason why a lot of it is called PREVENTIVE maintenance!
