That detail strikes me as a little strange, too. Prehaps they were on their way home from the grocery store when they were attacked.
Oranges I could easily understand. You wouldn't need any kind of galley for the crew to eat oranges while out on a patrol. But potatoes?? As I said, this makes no sense to me whatsoever.
Maybe that grocery store was in Cambodia. (yeah, that's the ticket.)
I got it! The spuds were ammo for their potatoe gun. I've read about these weapons here on FR. They leave a nasty red welt, and, if the VC weren't wearing their safety goggles, they can put yer eye out.
I imagine the DOD was experimenting with this type of ordinance because it is silent, and thus, ideal for secret missions to Cambodia.