Re: Newbe with no experience buys big boat
Thanks for the info, Jbaffoh. And thanks for reading the book!
I believe it also matters how well your holding tank is ventilated. The familiar sour, "gas station restroom" smell found on too many cruising boats (where the san system sees heavy use) is the result of anearobic bacteria: bacteria that thrive as long as there is no oxygen. Let plenty of air flow through the holding tank, and when it swashes around the waste is aerated and the anearobic bugs die - the aerobic bugs don't stink.
You're right - what's in the hoses matters a lot. To prevent that common anaerobic stink, you'll have to make sure all guests do what they are supposted to do. Flushing the hoses clear of waste, every time, means the holding tank will fill up faster in port or at anchor.
Composting heads are not perfect, but I feel they are a viable alternative, with a couple of caveats. The two most wonderful things about them are: no pump outs, ever, and no possibility of anything getting clogged, ever - no hoses, pumps, or valves at all.
I like the idea of being able to get rid of the sanitary waste as solid waste, with the rest of the garbage, ashore. No need to visit a pumpout station, and no need to dump a holding tank into the pristine waters off a beach or in a lagoon.
Couple that with the SPACE you save by not having a holding tank and the associated plumbing.
The AirHead system and similar marine composting tanks have greatly increased in price since I bought mine almost ten years ago. Then again, almost everything in the West catalog has greatly increased in price - if you're installing a totally new system, I'd guess that the composting unit would be less expensive, total, than a good quality standard head with the assoicated tank and plumbing.
Thanks for the input!