Federal law tends to treat employees of airlines and railroads, and those working aboard ships, differently than others. And so, who is a seaman and who is not often matters.
Take the case of casino riverboats. Unlike Jacksonville, which has taken advantage of Florida law allowing race tracks and card rooms, other cities in other states see their gambling halls limited to riverboats. Those spend vast majority of their time moored, but they are capable of cruising and occasionally do.
Courts have disagreed on whether their employees are seamen – and those courts’ reasoning might apply equally to employees on those boats providing lunch cruises on the St. Johns River and elsewhere, and that moor regularly, never traveling overnight. In that tangled web of precedents, it may be that not all aboard ship are treated equally, and that waiters and barmen may be less of a seaman than those operating the craft. It also may be that their status will not be the same under different statutes, as each may define a seaman differently. (The laws’ differing purposes trump a dose of simplicity.)
As in many other areas, those working aboard ships and those who employ them should consult a knowledgeable attorney to be fully aware of the ins and outs of their legal relationship.