Unless you have a leak,
nothing you put in the holding tank or put down the toilet will cure odor inside the boat. Stagnant decaying sea water can produce an odor very like urine...and I'm betting the problem has nothing to do with your sanitation system, but is due to a bilge in desperate need of real cleaning--not just something poured into the brew, but a thorough cleaning with detergent and water, followed by an even more thorough rinsing. If you tell me that your ice box drains into the bilge, I'd bet money that's the source of your odor--at least the odor in the v-berth. You could have two problems: stagnant seawater trapped in the head intake and in the channel in the rim of the bowl. That the odor went away during a long sail (when you used the head and flushed out the stagnant water), but returned after the boat sat in the heat for a while is a good clue that that's a highly likely source. Easiest way to find out: close the seacock, disconnect the head intake hose from the thru-hull and stick it in a bucket of fresh water that's LIBERALLY laced with white vinegar. Pump the whole bucketful through the system. You can then reconnect the hose, but do NOT open the seacock...use cups of fresh water from the sink to flush the head. If you have no odor in the head when you come back the next weekend--bingo...you've found the source for part of your problem. You'll find a permanent cure for it in the article called "Intake Odors" (or something like that...I can never remember exactly what I called 'em 6 months after I've written 'em) in the Reference Library of the Head Mistress forum. So try that and CLEAN your bilge...if you still have the odor, get back to me.
