Whenever the Commandant, the District Commander, or the Captain of the Port finds that the application of any provisions contained in §§ 126.15 and 126.16 is not necessary to the safety or security of the port and vessels and waterfront facilities therein, or that its application is not practical because of local conditions or because the materials or personnel required for compliance are not available, or because the requirements of the national defense justify a departure from such provision, the Commandant, the District Commander, or the Captain of the Port may waive compliance with such provision, to the extent and under such requirements as they determine.