Spare parts….spares for everything, you are going to need them!  Living aboard full time is hard on gear, add in sailing, rough conditions, salt spray and things wear out faster.  Since October 2016 (it is now April 2017) we have replaced or repaired or serviced the following,

-electric bilge pump, replaced
-head, complete service kit for pump
-bow pulpit, re-bolt
-auto pilot, install spare, send original for service
-end for end second reef outhaul, had chafed area at end of boom blocks, been used a lot this winter
-engine belt, replace
-change oil and fuel filters
-replace key and preheat switches on engine
-rebuild manual bilge pump
-watermaker, replace discharge line, install pump rebuild kit and new motor
-dinghy engine, change oil including lower unit, remove and clean carb twice
-windlass, send to manf. for warrenty service
-snubber line, replace broken one, requiring new thimbles and chain hook

Those are the items I remember, there are probably more, Cruising is hard on gear so spare parts for as many systems as possible need to be carried,  you also need the tools and where applicable the service manuels.