Can't be true since ships generally p*** port to port. That's left to left for you land lubbers. That what we do on US roads but not what the UK does.
I have no idea why the difference in the side of the road we drive on, but I do know that when going from one system to the other a certain amount of confusion will exist, especially when entering an intersection with no one else on the road to guide your decision. An Aussie friend taught me a very easy lesson to ensure that I will always make the right lane choice. He put it very succinctly and it never fails, "***** in the Ditch!" Think about it, the p***enger always is closest to the the "ditch." It works no matter what country you are in.