Bulk carriers are cargo ships used to transport bulk cargo items such as ore or food staples (rice, grain, etc.) and similar cargo. They can be recognized by the large box-like hatches on their deck, designed to slide outboard for loading. A bulk carrier could be either dry or wet. Most lakes are too small to accommodate bulk ships, but a large fleet of lake freighters has been plying the Great Lakes and St. Lawrence Seaway of North America for over a century.
Container ships are cargo ships that carry their entire load in truck-sized containers, in a technique called containerization. They form a common means of commercial intermodal freight transport. Informally known as “box boats,” they carry the majority of the world’s dry cargo. Most container ships are propelled by diesel engines and have crews of between 10 and 30 people. They generally have a large accommodation block at the stern, directly above the engine room.
A multi-purpose ship (sometimes called a general cargo ship) is used to transport a variety of goods, from bulk commodities to break bulk and heavy cargoes. To provide maximum trading flexibility they are usually geared (supplied with cranes), and modern examples are fitted for the carriage of containers and grains. Generally, they will have large open holds and tween decks to facilitate the carriage of different cargoes on the same voyage. The crew will be highly competent in the securing of break bulk cargoes and the ship will be equipped with various lashings and other equipment for sea fastening.
Refrigerated ships (usually called reefers) are cargo ships typically used to transport perishable commodities which require temperature-controlled transportation, mostly fruits, meat, fish, vegetables, dairy products and other foodstuffs.
Roll-on/roll-off ships are ships designed to transport wheeled cargo such as automobiles, trailers or railway carriages. RORO (or ro/ro) vessels have built-in ramps which allow the cargo to be efficiently “rolled on” and “rolled off” the vessel when in port. While smaller ferries that operate across rivers and other short distances still often have built-in ramps, the term RORO is generally reserved for larger ocean-going vessels, including pure car/truck carrier (PCTC) ships.
Tankers are cargo ships for the transport of fluids, such as crude oil, petroleum products, liquefied petroleum gas (LPG), liquefied natural gas (LNG) and chemicals, also vegetable oils, wine and other food. The tanker sector comprises one third of the world tonnage.
A barge is a flat-bottomed boat, built mainly for river and canal transport of heavy goods. Most barges are not self-propelled and need to be moved by tugboats towing or towboats pushing them. Barges on canals (towed by draft animals on an adjacent towpath) established the conditions supporting the early industrial revolution in both Europe and the American Northeast but later after they made possible steam locomotive prime movers riding iron rails – after both could grow (and mature) to become commonplace and capable – contended with the railways and were outcompeted in the carriage of people, light freight, and high value items due to the higher speed, falling costs, and route flexibility of rail transport. Carriage of bulk goods also gradually lost ground to freight railways as train capacity and speeds continued to climb. Even underpowered early rail networks could usually reach places only an outrageously expensive canal might be built, and once Iron T-rails and higher powered locomotives became possible, the far cheaper to build railways were unfettered and independent upon water sources, whilst mostly unplagued by the seasonal problems (restricted by icing) of temperate latitude canals which suffered ice and freshet flooding damages with dreary regularity. When floods did affect railways, restoration of services was usually comparatively rapid.
Cable layer is a deep-sea vessel designed and used to lay underwater cables for telecommunications, electricity, and such. A large superstructure, and one or more spools that feed off the transom distinguish it.
Coastal trading vessels, also known as coasters, ships used for trade between locations on the same island or continent. They are often small and of shallow draft, and sometimes set up as self-dischargers.
A tugboat is a boat used to maneuver, primarily by towing or pushing, other vessels (see shipping) in harbors, over the open sea or through rivers and canals. They are also used to two barges, disabled ships, or other equipment like towboats.
Open hatch general cargo ships are designed to transport forest products, bulk cargos, unitized cargoes, project cargoes and containers.
Semi-submersible heavy-lift ships often move particularly large, heavy, or bulky goods that other ships cannot handle well. Such off-size goods include ship hulls, premade construction materials, other seagoing vessels, power plant components, cast steel objects, and a variety of very large or heavy goods.