'Jo and I took some Pett bags along on last year's Cruise up in the Northwest. All we did was to line the Port-a-pottie with them. Best of both worlds. We try not to use the dang thing period, but the few times nature called away from dockside we used the Pett, then discarded at the first appropriate facility. The P-o-P never got anything in it's tank and we never had to deal with it...BUT..it was there and ready to go if we ran out of bags WHICH WE DID! hahaha DIDN"T WE GARY??!! Here's a hint....if you are on a cruise and find a new toy (toy?) that you really like...but are running out of...don't go around bragging about how great your new (toy) is before you pull into port ready to hike up to West Marine and buy some more. Otherwise when you stroll into the West Marine at Friday Harbor and say "Hey, do you have any Pett bags?" you'll wonder why the two clerks get a funny look on their face and say to each other "what is it with the PETT bags today?" "Mr. You are like the 6th person to come in here asking for them and we only carry two boxes!" hahaha or.....If You are gonna brag....be the first one into port!!!! HAHAHA ..........Later when we saw Gary he had a big smile on his face!!!! We all had a good laugh.......and the West Marine guys probably still have 6 boxes sitting on the shelves awaiting our return next year!!!! HAHAHA Sean, Jo, and yes, Bosun :-)