This part applies to all passenger vessels over 100 gross tons, carrying more than 12 passengers for hire; making voyages lasting more than 24 hours, any part of which is on the high seas; and for which passengers are embarked or disembarked in the United States or its territories. It does not apply to ferries that hold Coast Guard Certificates of Inspection endorsed for ``Lakes, Bays, and Sounds'', and that transit international waters for only short periods of time, on frequent schedules.