What Quiet Riot said.
The clear bowl filters are intended for use with outboard motors, or to be mounted externally in a open area.
For inboard motors where there is a potential for the engine to start a fire in an enclosed compartment, Racor makes a version of the filter with a solid metal bowl that is not transparent. The boxes on the respective filters have the application information and disclaimers on them.
If the clear filters are not Coast Guard approved, someone should tell the maintenance guys who install them on Coast Guard RIBs