What you really need are...
Schematics/owners manuals/installation & maintenance instructions for each piece of equipment on the boat NOW....'cuz in 20 years, it's a safe bet that most of it has been replaced at some point. Most of that info can be downloaded from the mfr's website. We can start with the toilet--which btw, doesn't work ANYTHING like the one in a house...they have nothing in common. What's the make/model? If you don't know, post a photo of it that shows the pump beside it or any "works" under it...NOT the bowl..all bowls look alike and 90% are made by the same company (Bemis).
You prob'ly oughta spend as much time as you can stand reading the discussions in the various forums here...some of it may feel like it's in a foreign language, but you'll catch on quickly.
So welcome aboard...and get me that photo (you CAN supply more than one, btw...no rule against it).
