Publisher Summary Ships are the largest moving structures designed and built by man. This chapter is a journalistic review of ships in operation at the present time. The first indicator for the size of a ship is usually the deadweight (dwt) measured in tones and the dwt is the weight a ship carries. With some designs, like passenger liners, the size can be indicated by the gross tonnage (GT) measured in tuns. With gas carriers, it is usually the volume of gas carried, measured in cubic meters. The size of a tug is gauged by the value of the bollard pull, measured in tones. Oil tankers are ships that carry liquid in bulk. They are slow-moving full-form vessels. Product vessels are tankers that do not carry crude oil. They are a spin off from the oil tanker design because they carry several different types of refined petroleum based products. Bulk carriers are vessels that carry cargoes such as grain, iron ore, sugar, bauxite, or coal. General cargo ships carry all sorts of general cargo, the main one being the carriage of grain. Hydrofoils are small craft that rise out of the water at the bow when at high speed.