[Sailor Steve]

I think you are right on the legality bit, but not entirely. The original idea was to stop neutral ships and inspect their papers. If they were carrying materials bound for an enemy country then they were indeed fair game. Of course with escorted convoys and armed merchants this quickly became impractical. If a neutral convoy happened to have an enemy escort it was probably considered off limits, but then why would they have an enemy escort?

The likelihood was of the ocassional neutral ship appearing in an enemy convoy, in which case they were indeed a valid target. Would the captain recieve a tonnage credit for the sinking? The tonnage would be noted, as well as the neutrality of the sunken ship.

I would say the zero-sum tonnage for neutrals is probably the best idea for the game.