The owner or master of every 1[mechanically propelled vessel], for which a certificate of survey has been granted, shall forthwith, on the receipt of the certificate, cause one of the duplicates thereof to be affixed and kept, affixed so long as it remains in force and the 1[mechanically propelled vessel] is in use, on some conspicuous part of the 1[mechanically propelled vessel] where it may be easily read by all persons on board.