As to the contract of engagement existing on the effective date of this Law, the renewal or alteration thereof which is exempted from obtaining certification by virtue of the provisions of Art.2 of the War-time Exception of the Mariners Law, and which is the newest one as counting back from the day of the promulgation of this Law, shall be considered, so far as the application of the provisions of Art.37 of the Mariners Law is concerned, as having been made at the time of the promulgation of this Law.