I recently purchased a Catalina 22 MKII. Inside the cabin it has a faint odor like dog pee; however, the previuos owner tells me a dog has never been on the boat. Is it possible the battery is giving off this smell? Should I have a totally enclosed battery? I've clean the carpet, wsahed all covers and weven washed the inside of hte cabin down with mild bleach but I still smell it.