NOT holding tank odor
There's no way that a Ronco tank would have permeated, so unless it's leaking at a fitting, it can't be the culprit...'cuz odor from inside a holding tank has nowhere to go but out the tank vent. A few possibilities: If the odor were in the head, I'd ask you when the joker valve in the toilet was changed last...'cuz joker valves wear out in about a year, and when the slit becomes stretched enough to become a hole, odor from inside the head discharge hose can escape through the toilet. When was the last time you cleaned your bilge--I don't mean just dumped in some bilge cleaner and/or bleach, but really CLEANED it...including flushing ALL the dirty water out? 'Cuz a wet bilge in desperate need of a real cleaning is full of bacteria and other critters that can make a boat smell like a swamp or sewer. If your ice box drains into the bilge, that would accelerate the conditions that create odor. A sump in need of a serious cleaning can also smell like a sewer. So can the chain locker if it hasn't been cleaned in a while. If neither of those are the culprits, look for trapped water somewher under the cabin sole...start where the odor is strongest.
