Don’t we have a NAVY for that?
The Coast Guard is better suited and trained for boarding and inspecting ships and boats. It’s what they do. The Navy has huge ships which do not stop to dispatch a launch and wait around like sitting ducks to retrieve the boarding party. The Coast Guard doesn’t tangle with foreign naval vessels, but they have far more firepower (and trainging and discipline) than pirates and terrorists.
I suppose the Navy could set up a unit of swift boats, or something similiar, but the Coast Guard is ready off-the-shelf.