spinner79,
This is not a helideck but a ship operation - mostly conducted as private operations (or corporate - a type of private operation). As such there are few regulations world-wide that would prohibit operations with singles (or twins operating in PC3).
In any case in 2005, and in deference to operations in the GOM, the ban on PC3 operations to helidecks was removed from ICAO Annex 6 Part III, Sections 2 and 3, and JAR-OPS 3. These operations would, of course, be conducted with exposure to an engine failure during take-off and landing.
For CAT (not these of course) there remains a restriction for operations over a hostile environment to be conducted in PC1 or 2.
So, no ban.
Jim