The use of a passenger ship as a symbol for China dates from the 1950s, if not earlier. This image is taken from a 1958 masthead book.
During the earliest phase of the Cultural Revolution (May to December 1966) a passenger liner appeared on a number of Maozhang. Although depicted moving from right to left and making a small bow wave, these early ships are devoid of the roiling "waves of revolution" that accompany some of the ships on later Maozhang.
Instead, the message seems to be one of plain sailing through calm seas and under azure blue skies. On some badges the impression of fair weather and calm progress is enhanced by the inclusion of seabirds flying above and behind the ship of state.
This later badge shows the passenger ship in much more turbulent seas
h. 12mm w. 25mm 1.2g
h. 29mm w. 16mm 2.1g
h. 30mm w. 19mm 3.0g
h. 18mm w. 29mm 2.3g
The badge at left is unusual because the obverse inscription is incuse rather than in relief