They use a pressure fresh water system to provide flush water for the heads. The system is connected via a series of manifolds and "one way valves."

I have no idea how many boats are set up this way, or if it is one specific boat, but I do know that it is set up in just that manner. (there were problems with the pressure system at one point, and we could not flush the heads)

I thought it was a tremendous waste of fresh water. But the skipper thought it was grand, as it virtually eliminated head smells. I gave him a copy of your book back when he had a smaller boat (that always had bad head smells.) He then moved up to a 41 footer with this system.

There were other systems I also questioned on this boat... the propane locker for instance had a drain through a hose that went through a locker in the upper portion of the swim step (two level step). I don't recall whether that locker was connected or not to the rest of the boat... But I always thought a propane locker should vent directly overboard.

One other system issue was that to shut off the engines, one pushed a button that activated a solenoid that cut off the fuel... two items that could fail (and did, at least once) that were needed to shut off the engine.

Some may read this as a bash to Hunters... I am just stating what I saw. Perhaps it was boat specific, but this boat came this way from the factory.