When you decide to follow a life at sea, raise your hand, and swear the oath, your first Merchant Mariner's Credential will be endorsed Ordinary Seaman, Wiper, Steward's Department (FH). The FH stands for food handler, and ordinary seaman is a deckhand; a wiper is the equivalent of a deckhand in the ship's engine department.
The entry level job for a certified seaman in the deck department is the "Ordinary Seaman." In this apprentice position, you'll be a seagoing janitor who's learning to tie the ship up, how to tie proper knots and splice lines together, and correct maritime procedure according to the way the ship's master wants things done. The next step on the way to command is the "Able Seaman".
A certified seaman who wants to follow the mechanical trades aboard a ship starts as a "Wiper" in the Engine Department. The job title is fairly self-explanatory; this fellow grabs a rag and wipes, keeping the interior of the engine room in order by tending to the proper disposal debris, refuse and trash from the engine room that must be accounted for in the ship's refuse log. While doing all this, the Wiper is studying to test for the next level, a "Qualified Member of the Engine Department."
The steward's department provides hotel services aboard all ships including cooking, laundry, cleaning the common spaces and, if requested, cleaning crew cabins. The entry level position is the "Food Handler" who passes out extra napkins and keeps the "mess" clean. The food handler may also assist the steward or the night cook as a galley hand, assisting in the preparation of the food.
If a vessel is small enough that certified seamen are not required, then the deck hand fulfills the role of the ordinary seaman, the wiper and the food handler, adding experience and sea time to his resume if he should chose to seek certification in the future. This possibly allows him to bypass the ordinary seaman's position by virtue of sea time accumulated and the ability to pass the Able Seaman's examination.