We have the original Owners Manual for our boat. Its reasonably thick and covers most of the original equipment, specs, plumbing and wiring diagrams, shaft dimensions, fuel burn rates etc. But, as the manual states, your equipment, layout, specs, etc may vary from what is actually on (factory installed or added later ) the boat. I have found that to be the case. The individual manuals that came with each item of equipment actually installed on our boat (and there are a myriad of them) are much more useful. Still, the Owners Manual is a nice thing to have and I do look at it from time to time.