Though Pirates Online has only a scant number vessel classes, ship can be found in all shapes and sizes.
| Term | Definition |
| barkadeer | A small pier or jetty vessel. |
| barque (also bark) | A sailing ship with from three to five masts, all of them square-rigged except the after mast, which is fore-and-aft rigged; a small vessel that is propelled by oars or sails. |
| brig / brigantine | A smaller, two-masted class of ship often favoured by pirates because of their speed and maneuverability. The term 'brig' also refers to a cage or room on a ship used to hold prisoners. |
| carrack or nau | A three- or four-masted sailing ship developed in 15th century Western Europe for use in the Atlantic Ocean. |
| clipper | A fast moving ship with three sails and a square rig. |
| Cog | A small warship. |
| fire ship | A ship loaded with powder and tar then set afire and set adrift against enemy ships to destroy them. |
| galleon | A large three-masted sailing ship with a square rig and usually two or more decks, used from the 15th to the 17th century especially by Spain as a merchant ship or warship. |
| galley | (1) A low, flat vessel propelled partly, or wholly by oars. (2) a ship's kitchen. |
| hulk | Gutted hulls used for other purposes like prisons or floating quarters or storage. |
| jolly boat | A light boat carried at the stern of a larger sailing ship. |
| long boat | The largest boat carried by a ship which is used to move large loads such as anchors, chains, or ropes. pirates use the boats to transport the bulk of heavier treasures. |
| lugger | A two-masted sailing vessel with a lugsail rig. |
| Man-of-War or Man O' War | A vessel designed and outfitted for battle. |
| pink | A small sailing vessel with a sharply narrowed stern and an overhanging transom. |
| pinnace | A light boat propelled by sails or oars, used as a tender for merchant and war vessels; a boat for communication between ship and shore. |
| piroque | Small canoe, often used by Caribbean pirates to overtake other ships. |
| Plate Fleet | Spanish galleons carrying silver and gold to Europe. |
| schooner | A fore-and-aft rigged sailing vessel having at least two masts, with a foremast that is usually smaller than the other masts. |
| Ship of the Line | A massive vessel designed to take part in the line of battle tactic in which the ships of a fleet form a line to fire combined broadsides. |
| sloop | Small, fast ship with a narrow, shallow hull and large sails. Normally, sloops had only a mainmast. |
| snow | A square-rigged vessel, differing from a brig only in that she has a mast close abaft the mainmast, on which a large trysail is hoisted. |
| tender | A vessel attendant on other vessels, especially one that ferries supplies between ship and shore; a small boat towed or carried by a ship. |
| wherry | A light, swift rowboat built for one person usually used in inland waters or harbors. |
| yawl (or dandy) | A two-masted fore-and-aft-rigged sailing vessel similar to the ketch but having a smaller jigger- or mizzenmast stepped abaft the rudder; a ships small boat, crewed by rowers. |