Polar Security Cutter Acquisition Act of 2019 This bill sets forth acquisition requirements for the U.S. Coast Guard to acquire any polar icebreaker, subject to an exception. The Coast Guard must (1) limit military specifications for such vessel, (2) ensure specifications and key drawings are complete before awarding the contract for construction, (3) ensure detail design of the vessel is complete before the start of construction, (4) use block buy contracting (permits the use of a single contract for more than one year's worth of procurement without having to exercise a contract option for each year after the first year), and (5) ensure all icebreaker hulls are science ready and that one is science capable.