Standing and running riggin parts.
Lines, blocks and tackle. A spare electric bilge pump and a manual one. A watermaker in your ditch bag. Some fabricating materials, pieces of wood, pipes, gasket material, U-bolts and clamps, screws nuts and bolts. Water hoses, fuel filters, water separator, impellers. Something will break and in accordance with Murphy's law you will not have a spare for that so be prepared to use ingenuity and tools to solve problem. I would rather have a good selection of tools and some basic materials than a bunch of spares. Don't forget the duct-tape. Design redundant systems for charging batteries, solar and perhaps wind to back up or complement alternator.