There are many jobs, this one is mine.
I am a Tug Captain in Norfolk, Va.
There are many jobs working on the water with companies that supply the tugs and barges that move products all around the world. Typically, an entry level guy, like yourself, comes into the industry as a "deckhand" or ordinary seaman (OS). Some work their way up to a the wheelhouse, while some choose engineer.
I did twenty years in the Navy, and took my experience and a small Captain's license and got a job on a tug. I gained the experience on deck, got a higher license, and moved to the wheelhouse.
I am the Captain of the Tracy Moran, a 4,200 horsepower azimuthing stern drive tug that supports the Navy ships at Naval Station Norfolk.
So, where to start...
First, there is a required document, issued by the Coast Guard. It is sort of like a driver's license for working on the water. It is called a Merchant Mariner Document (MMD), also called a "Z card." You can find information on it here
USCG National Maritime Center
Second, and most companies will help you get one... A TWIC. It is a Transportation Workers Identification Card. Lots of government red tape, but you have to have one.
Where to look... Once you have a Z-card, look for companies with tugs, barges, ferries, any kind of water commerce. They all need crews. Call and tell them you have a Z-card, but no experience. You are looking for a deckhand job.
Typically for boats like tugs that are always on the move, the schedule is normally two weeks on and two weeks off. At the end of the "hitch", the new crew arrives to take over, wherever the boat happens to be.
Check out this website:
Moran
Lots of jobs in the Gulf of Mexico supporting the oil rigs.
If I can help more than this, PM me and I will give you my phone number.
I have been on the water my whole life. Sure beats sitting in an office.