If You Were Hurt on a Dock or in a Shipyard, the Longshore Act May Apply
The Longshore Act starts from a broad definition. Under 33 U.S.C. § 902(3), an "employee" means "any person engaged in maritime employment, including any longshoreman or other person engaged in longshoring operations, and any harbor-worker including a ship repairman, shipbuilder, and ship-breaker." If you were hurt loading cargo on a terminal, repairing a ship in a yard, or doing harbor work alongside a vessel rather than as part of its crew, this is usually the statute that comes up.
If you were part of a vessel's crew, the same definition points the other way. It does not include "a master or member of a crew of any vessel," which is why a seaman and a Longshore Act employee are usually treated as separate categories. If your job is office clerical, security or data processing work, marina work, aquaculture work, or building or repairing certain recreational vessels, the definition may leave you out as well, among others; for several of those groups the exclusion applies if they are subject to coverage under a state workers' compensation law.
If you work offshore, there is another layer. Under 43 U.S.C. § 1333(b), compensation "shall be payable" under the Longshore Act for disability or death from injury occurring as a result of operations on the outer Continental Shelf to explore for, develop, remove or transport by pipeline its natural resources. That provision also excludes a master or member of a crew of any vessel. Not every offshore worker is a seaman, and not every offshore worker falls under this extension; status and location decide it.
What is at stake for you is the kind of remedy. The Longshore Act is a compensation statute, which works differently from the negligence action a Jones Act seaman may bring, and its claims follow their own deadline rules. Because the line between the two is fact-specific, where your job falls is often one of the first things an attorney can help sort out.