Added resistance of ships in waves is determined by a newly developed potential flow method, a Rankine source method, a strip method, and by RANS (Reynolds-averaged Navier-Stokes) equations solvers. For 10 ships, results of all these methods are compared with each other, with published computed and experimental results, and with approximation formulae submitted to IMO (International Maritime Organisation). The focus is on waves that are short relative to ship length. In spite of the large scatter of results, existing prediction methods appear useful for practical application.
