Sandy.467

You can wait until they become free again...
in the window where you get your provisions and such, it'll say how long you have to wait. Usually 12 or 13 hours.

Upgrade your boat and get 10 energy and 5 provisions. Was easier when you could just find islands with barrels and dark colored barrels had better pieces. Since the upgrade haven't found a single piece. Still not spending $$$ though.

On the islands, that is the only way I know of to get more food cans. And the free ones don't update until midnight your time. It does make it challenging.