I've got a Four Winns 224 with a marine head. Love it, but don't have easy access to a pump out station and I have two kids who love to use the head. Someone told me that there is a way to rig the head with a bag and/or liner so that the waste stays in the head and does not go into the holding tank so that you can pull the bag out when you're done for the day and just throw it away. Sounds simple enough, and I'm sure I could figure it out, but, if you've done something similar to that, would be interested to hear about how you rigged it.