Developments are discussed under the headings size, speed, seakeeping and ship handling. There is a note on trends in ship hydrodynamics research. Size limits are likely to be set by geography rather than technology; million tonne ships are possible but seem unlikely. Speed in displacement ships is unavoidably expensive; high speeds are possible with hydrofoils and hovercraft but costs are likely to limit their use. In seakeeping means of roll damping will be improved, as will the ability to sustain service speeds in adverse weather. Considerable improvements are probable in the handling qualities of ships, with gains in safety and port efficiency.