(a) Each passenger vessel must have a lifeboat or rescue boat for each six liferafts when—

(1) Each lifeboat and rescue boat is loaded with its full complement of persons; and

(2) The minimum number of liferafts necessary to accommodate the remainder of the persons on board have been launched.

(b) A passenger vessel engaged on a short international voyage that also complies with the standards of subdivision requirements for vessels on short international voyages as described in subchapter S of this chapter may have a lifeboat or rescue boat for each nine liferafts when—

(1) Each lifeboat and rescue boat is loaded with its full complement of persons; and

(2) The minimum number of liferafts necessary to accommodate the remainder of the persons on board have been launched.