A shuttle tanker is a specially designed ship that loads oil from deep-sea oil fields, reservoirs, or other ships, and then transports and offloads the cargo at refineries and terminals. Shipbuilders create these enormous ships with special features that can withstand harsh weather and are capable of offshore operations. If for any reason one shuttle tanker cannot make a voyage, another may take its place, allowing operations to continue, whereas as a pipeline malfunction would bring oil transport to a stop.
The ship may measure 755 to 886 feet (230 to 270 meters) in length and weigh hundreds of thousands of tons. The specially designed double hulls of the shuttle tanker not only withstand the rigors of the sea, but also prevent possible oil leakage. Some may have as many as 12 tank compartments, containing heating units that maintain the oil in a liquid state. One end of a large pipe enters each tank, and the other end, on deck, is equipped with hose connectors. These vessels can hold around 14 million gallons (52.99 million liters) of crude oil and travel at speeds of 16 knots (18 mph or 29.6 kph).
One end of the tanker deck houses a large structure, which contains the living quarters for the crew and the wheelhouse at the top. The wheelhouse, where the captain and crew work, generally contains computerized navigational equipment. The computerized dynamic positioning (DP) system, along with propellers, rudders, and thrusters, automatically place and maintain the vessel in a safe position for loading and offloading. This equipment enables the ship to operate regardless of wind and sea conditions.
The DP uses complex technology that includes reference systems, gyrocompasses, and vertical sensors, combined with wind sensors that monitor and control the propellers, thrusters, and power supplies. Though the dynamic positioning system may function automatically, the crew can manually change the settings and the vessel's position as needed. The system allows complete maneuverability of the shuttle tanker without requiring tugboat assistance.
One of the differences between shuttle tankers and other types of ships includes shorter hauling distances between crude oil pick-up and delivery. The workload aboard these vessels is typically more demanding than that of oil tankers. As pick-up and offload voyages tend to be shorter, the crew must precisely execute the relevant operations a greater number of times. Standards require that crews must load, offload, and handle equipment in a manner that prevents possible environmental contamination.
Pipelines to and from deep-water offshore oil fields and holding stations are generally impractical and cost prohibitive. Shuttle tanker companies typically obtain long-term contracts with offshore fields, reservoirs, and refineries. This method of oil transportation also guarantees pick-up and delivery.