Vessel Types.

Carries break-bulk goods: cargo stowed in individually counted units such as bags, cases, drums, coils and machinery. Most ships have their own cranes, so they can work ports without shore gear.

Single-deck ship with large hatches for unpackaged dry cargo in volume. Small classes are geared, Capesize and larger need shore loaders. The largest ore carriers reach 400,000 DWT.

Cellular ship for ISO containers, sized in TEU. About 90% of non-bulk cargo moves on container ships; since 2023 the largest carry over 24,000 TEU.

Cooled holds for perishables. Palletised cargo goes in through side doors and pallet lifts; refrigerated container ships instead power a cooling unit on every reefer box.

Wood chips, the raw material for paper, are light for their volume, so the hold is widened sideways as far as possible and ballast sits only in the bottom of the hull. Cargo is handled by grab cranes and belt conveyors.

Large ship for the live export of sheep, cattle and goats, built new or converted from a container ship. Pens sit on open decks or inside closed holds; ventilation is the key design factor.

Moves large quantities of unrefined crude oil from where it is produced to refineries. Crude tankers are the largest tankers afloat: a VLCC carries about 2 million barrels.

Carries refined petroleum products such as gasoline, diesel and jet fuel. Product tankers are generally much smaller than crude carriers, from well under 10,000 DWT up to about 80,000 DWT Panamax ships.

Built for liquid chemicals listed in chapter 17 of the IBC Code (MARPOL Annex II). Tanks are coated (phenolic epoxy or zinc) or stainless steel and segregated so several cargoes travel at once.

Carries bitumen and asphalt hot, up to 200 °C, in independent cargo tanks. Heat makes the tanks and pipes expand, so the design is built around thermal expansion.

Liquefied petroleum gas is kept liquid by pressure, by cooling, or both. Most oceangoing fully pressurised LPG ships have 3 to 5 spherical or cylindrical tanks.

Natural gas is carried as a liquid at about -162 °C, which shrinks it about 600 times, in insulated membrane or spherical (Moss) tanks.

Wheeled cargo is driven on and off over ramps at the stern, bow or side. The hold is laid out like a multistorey car park.

A Ro-Ro with passenger decks (roll-on/roll-off passenger). Trucks, trailers and cars drive onto the vehicle deck, passengers and drivers ride above it. Runs to a timetable on short-sea lines, so it moves much of the trailer freight across the Baltic, the English Channel, the North Sea and the Mediterranean.

A hybrid of a Ro-Ro and a container ship: vehicle decks inside the hull, containers stacked on top or in cells. Carries containers, heavy equipment, oversized cargo and cars on one sailing. Atlantic Container Line's G4 class (296 m) has 5,270 lane metres on seven Ro-Ro decks and 3,807 TEU.

A Ro-Ro built for new vehicles. The pure car and truck carrier (PCTC) has liftable decks for taller units and stronger decks for high-and-heavy cargo; a 6,500-unit car ship can have 12 decks.

Project cargo ships load very large, heavy items with their own cranes, typically 13,000 to 19,000 DWT. Semi-submersible ships flood ballast tanks to sink the deck, float the cargo over it, then pump out and lift it.

Supplies offshore oil and gas platforms and brings cargo back to shore. Cargo tanks hold drilling mud, pulverised cement, diesel fuel, water and drilling chemicals; the family also includes AHTS and other offshore support ships.

Handles anchors for oil rigs, tows the rigs to location and secures them. Also does supply runs between land bases and drilling sites and assists tankers while loading.