Are Maritime Weddings at sea Legal and recognized by the United States Government?

Depends on the flag of the ship in question.

The US federal government does not have any laws on marriage, laws are all at the state level. If the wedding and marriage is otherwise legal by all terms of the state then it is legal and binding. **can not be same sex in states that don't accept same sex, can not be for multiple wives, can not be underage marriage if that is not allowed in that state.