So what are the rules if they aren't? Well, let's turn to the Convention of the High Seas, article 22:
1. Except where acts of interference derive from powers conferred by treaty, a warship which encounters a foreign merchant ship on the high seas is not justified in boarding her unless there is reasonable ground for suspecting: (a) That the ship is engaged in piracy; or (b) That the ship is engaged in the slave trade; or (c) That though flying a foreign flag or refusing to show its flag, the ship is, in reality, of the same nationality as the warship."That seems fairly straightforward. In fact, the more I think about it, the more it feels like using San Remo at all puts the cart before the horse, since it absolves Israel of its influence and control of the Gaza strip. It puts all the responsibilities of a sovereign state on Gaza, without the rights of a sovereign state.