When I was earning my 'Officer of the Deck Surfaced' quals, I was taught that submarines are considered 'deep-draft' vessels and therefore the following applies:
"Under Rule 9 of the International and Inland Rules of the Road, all vessels less than 20 meters (66 feet), vessels engaged in fishing and all sailboats cannot impede the passage of a vessel that can only operate safely in a narrow channel or fairway."
I remember conning my boat (USS Nautilus) into San Diego and the sailboats were always getting in our way. That inspired me to include bunches of suicidal sailboats in my Dangerous Waters scenario, "We Dive at Dawn".
