Interesting. I frequent a sailing forum and there has been some discussion there about autonomous shipping. Most of the members have expressed worry about the risk of collisions. After all, the "rules of the road" (as the rules for which ship/boat has the right of way are called) are very complicated and seldom understood even by human skippers. In fact, there is a discussion going on right now about whether or not the members display "day shapes": objects attached to the rigging which tell other boats whether you're anchored, motor-sailing, etc. More than a couple members have said they never do.
OTOH, quite a few members have mentioned what is known as "the law of gross tonnage". This means that, even if you technically do have the right of way, if the other ship is bigger, you're better off just staying out of its way. This would also probably be a good rule to use when encountering an autonomous vessel.
At any rate, I suppose there's little chance of a cruising yacht colliding with a submarine. But with the collision of a U.S. submarine into a seamount in 2021, I wonder ...
