A patent shall not prevent the use of an invention for the purposes of the navigation of a foreign vessel within the jurisdiction of any of His Majesty's Courts in the United Kingdom, or Isle of Man, or the use of an invention in a foreign vessel within that jurisdiction, provided it is not used therein for or in connection with the manufacture or preparation of anything intended to he sold in or exported from the United Kingdom or Isle of Man.

This section shall not extend to vessels of any foreign state of which the laws do not confer corresponding rights with respect to the use of inventions in British vessels while in the ports of that state, or in the waters within the jurisdiction of its courts.