[Mongo Johnson]

From another yakker

Essentials to carry on the boat
-Spare fin mast
-Tools to repair the drive (my kit comprises spanner, pliers & swiss army knife)
-Spare sprocket chain cable & idler cable
-Spare split pins (need them for my fin masts - you may not need these depending on your drive)
-Spare nuts (for the drive - all too easy to drop them overboard/into long grass or sand)
-Knowledge of how to adjust/repair your drive (there are different models some more easy to adjust/repair than others and if you are making an extended trip you have a duty to be self-reliant)
-For a longer trip I carry a spare pedal (FWIW & IMHO the exercise-bike pedal straps are a complete waste of the world's natural resources but if a pedal shaft breaks - and this happened to me once - your ability to make progress will be severely reduced)
-Spare rudder pin clipped to underside of rear hatch lid (standard on all Hobies I believe)

Safety gear (minimum)
-PFD
-VHF
-Baler (I take a sponge)
-Light (Mine is a tiny LED bike light that is powered by a hearing aid battery)
-Spare clothing to suit conditions you might encounter
-Length/lengths of strong light line.

Stuff to carry in the car (shouldn't be too many real essentials in this list - most of what you NEED you NEED to carry on the boat). FWIW I try not to forget to take:
-Spare tyre for cart wheels (if pneumatic like my C-Tug) pump and tyre levers
-Charger for FF/GPS

My spares (other than the finmast & pedal), toolkit, vhf & light all fit in a watertight sandwich box-sized "otterbox" (Brand name). This and the spare fin mast & pedal go inside the boat via the centre hatch. Even if you do this you need to ensure that you can reach them if you need them because they do tend to slide about if you don't do something to stop them.