Dr. Lecter
Contributor
Wookie, I don't know
about commercial diving, but I do know about statutory interpretation and admin law. Whether OSHA is preempted is an interesting question; I think your analysis is right, but I can see where Scubakevdm is getting confused.
USCG could promulgate regulations governing recreational diving from an inspected vessel. It has instead chosen to regulate only commercial diving and exempt recreational and certain other types of diving from those specific commercial diving regulations. So it seems like OSHA is not preempted because although the USCG has the authority to regulate, it has not exercised the authority, which is necessary for preemption to occur. Hence, he's saying USCG hasn't regulated the activity and it "falls through" into OSHA's regulations. Of course, all the other USCG regulations still apply to any activities on an inspected vessel, including any type of diving.
He's probably misreading the statutes, case law, and OSHA memoranda on this though, because it's clear that the question of whether OSHA has been preempted or not is only parsed carefully for uninspected vessels. For inspected vessels, even OSHA itself has recently said that all personnel on the vessel that qualify as seamen are exempt from regulation -- regardless of what they do. OSHA gives the following example that's highly analogous to a dive charter boat:
"A gaming or entertainment vessel that is inspected will have personnel that are U.S. Coast Guard-licensed or documented (such as masters, mates, engineers and crew) and personnel that are not licensed or documented (such as card dealers, entertainers, musicians, bartenders, and restaurant employees). Since the work of the inspected vessel includes gaming or entertainment, all personnel aboard whose work includes gaming or entertainment are considered to be seamen and are covered by the U.S. Coast Guard for purposes of safety and health."

USCG could promulgate regulations governing recreational diving from an inspected vessel. It has instead chosen to regulate only commercial diving and exempt recreational and certain other types of diving from those specific commercial diving regulations. So it seems like OSHA is not preempted because although the USCG has the authority to regulate, it has not exercised the authority, which is necessary for preemption to occur. Hence, he's saying USCG hasn't regulated the activity and it "falls through" into OSHA's regulations. Of course, all the other USCG regulations still apply to any activities on an inspected vessel, including any type of diving.
He's probably misreading the statutes, case law, and OSHA memoranda on this though, because it's clear that the question of whether OSHA has been preempted or not is only parsed carefully for uninspected vessels. For inspected vessels, even OSHA itself has recently said that all personnel on the vessel that qualify as seamen are exempt from regulation -- regardless of what they do. OSHA gives the following example that's highly analogous to a dive charter boat:
"A gaming or entertainment vessel that is inspected will have personnel that are U.S. Coast Guard-licensed or documented (such as masters, mates, engineers and crew) and personnel that are not licensed or documented (such as card dealers, entertainers, musicians, bartenders, and restaurant employees). Since the work of the inspected vessel includes gaming or entertainment, all personnel aboard whose work includes gaming or entertainment are considered to be seamen and are covered by the U.S. Coast Guard for purposes of safety and health."