Re: Parts to keep onboard?
I used to always carry to my boat one of these:
available very cheap at places like Walmart etc
http://www.preparedness.com/smalutsupbox.html
It floats and I kept my flares, whistle, emergency flag, First aid stuff, black plastic tape, fuses, small coil of of elec wire, wire ties, matches, flashlight, spare in-line fuel filter, extra gas cap for my 6 gal tank etc. My starter rope stores under the outboards cover and shear pins are in there too. My outboard also came with a small tool kit with all the stuff you might need like plugs, extra plastic kill switch key, screwdriver, wrenches, plug socket etc.
Last boat I bought now has lockable lockers, so I still keep everything in an Orange waterproof case which is a little bigger now. It's an orange Pelican case.
The plastic zip lock bags would always break on me at some point. Nice part of putting that kit together is that you have a lot less stuff to have to remember to bring each trip on smaller boats.
Not part of the kit . . . but the best tip I ever got was from my boater BIL who said to always carry a spare 2 gal plastic gas can. I keep it in the bow hatch and it's been a lifesaver when I'm out on big waters and am running low on fuel. I've pulled up to the only gas dock around and they are closed or out of gas! Also brings me up to over 8 gallons on board.
I think the one I bought is 2.5 gal and was about $10 at sears. My 6 gal tank has no gauge and it's in a closed locker, so having the spare allows me not to have to keep getting up and checking it. I can travel a huge distance with 2 gallons at cruising speed when I've had to use it.