As John said it depends on how long you are going to be out, how far from support facilities will be, how old your boat is and as importantly what are your mechanical skills.
In addition to the previous suggestions, all of which are good, I would suggest diesel
injectors (has to be properly protected and stored), gaskets and o rings for heat exchangers, Rydlyme or similar cleaning
solution, R/W pump- not just impeller, starter brushes
and diodes for the alternator
, maybe even spairs, all of the rigging
shackles, clevis pins, etc that you can think of.
A complete tool set with 3/8" drive socket set from 6-19 mm and box and open end wrenches, pullers, pliers, hacksaw, .....