I believe Ultima I and II are strictly turn-based, in the sense that if the player does not move no food is consumed. However Ultima III seems to be away from this tradition and I'm wondering if there is a way to go back?
Thanks in advance.
There are two aspects that make the game not strictly turn based.
1. If you don't input a command for 5 seconds, the game will skip your turn; this is probably what you've been noticing with respect to your food. It would probably be possible to change the time limit with a hex editor, or even hack the game so that it never skips your turn, but I don't know if anyone has actually released such a hack (maybe see if the upgrade mod has an option for that?). (Note that the speed of the computer does not affect this, interestingly enough.)
2. The whirlpool moves in real time. Unfortunately, this would not be as easy to fix as 1; a code fix would not be as simple as modifying a single instruction. (Playing with a frame limiter will at least slow the whirlpool down to manageable levels, however.)
I don't remember whether the wind changes in real time or not.
As for other Ultima games and whether they're turn based (based off the DOS versions):
1: Turn-based except for the mandatory space fighting minigame.
2: Not turn-based, because there is a time limit per turn. On modern systems (without slowing down the game significantly or adding a frame limiter), the game will run so fast that you don't have enough time to enter commands without wasting a bunch of turns, making the game basically unplayable. (That's assuming, of course, that the game doesn't crash due to trying to divide by zero while calibrating its timer, of course.)
4: The wind and moongates are in real time, as is the movement of the balloon.
5: If you hoist the sail of a ship, the game will play in real time until you furl it; hoisting the sail is a way to go quickly over water, but isn't actually needed for anything.
6: Is strictly turn-based as far as I can tell. (Only game in the series (not counting Akalabeth) that is actually strictly turn-based.)
7 and later: Game is fully real-time, as they ditched the turn based gameplay of past entries (and the games suffered as a result).