Re: drain plug wrench
Don't have any tools that float, but the ones I use over the side (especially the prop wrench), have a lanyard on them so they don't go too far if dropped in the drink. Have a tool set specially put together for and never leaves the boat. All in a plastic tool box. Have another plastic tool box with spare fuses, bulbs, electrical crimp connectors, velcro strips, various tyraps, electric and duct tape, hose clamps, 5 minute underwater epoxy and some wooden plugs and hammer. All the stuff in that box is in zip-loc bags to keep em dry.
The cresent wrench (we call it cresent hammer) has a very convenient hole in the handle, perfect for a lanyard. Drain plug also has a lanyard loop on it that I hang on steering wheel when not in transom, so I can't miss it. Carry a spare in tool box too.
PS: Before leaving the driveway, I always start her up and run her for a little while on the hose, do all the normal checks and put plug in when I shut her down. Plug gets double checked at the ramp. Many years ago, forgot it one time. NEVER again will do that. Took too long to live that one down.