Some easy basics
I'm always nervous answering a question in Peggy's area of expertise

but there are some simple guidelines I have used and am (so far) trouble free.1) If you didn't eat it or drink it, it doesn't go in the head. Make sure guests are specifically told this.2) Don't use household chemicals in the head. You have to convince the spouse that dumping Pine-Sol in the bowl is a not a good thing. Use specific marine head treatments if it goes in the bowl, thus through the plumbing. I find an occasional double glug of vegetable oil flushed through lubes the seals, etc.3) Be sure you use enough water to flush waste through the hoses, particularly for the long run from the aft head4) If the head smells when you flush it (water coming in smells) it is due to algae in the intake, usually due to light/infrequent use. Run more water through it by flushing. You will get this in SoCal.5) When on land, make that morning trek to the marina facilities. The less solid wate in the tank, the less chance for odor.6) Don't let the tank overflow such that the vent line spills. This is an air vent, not to be used as an overflow. Should this happen, backflush it.7) Use a commercially available marine tank treatment8) Pump it out, don't let it just sit and turn into a science project. Since you are in SoCal, I bet your pumpouts are free, don't be shy about rinsing with fresh water and some bleach and pumping out again. Be sure the bleach goes in throught the deck fitting, not the head. Could also pumpout before you leave the marina, put in some bleach water and empty when legal on your way to Santa Cruz Island.Peggy, have I been taking good notes?Congrats on the new boat, I own an earlier Passage 42. You will really enjoy it. Lots of nice anchorages at Santa Cruz Island, bring hefty anchors and lots of chain as it can get VERY windy at night.