The speed/power characteristics of ships have always been at the core of ship design. To prove contractually agreed values, speed trials are conducted by the yard prior to delivery of the ship to the owner. In the past schedule integrity of the vessel was often the most important factor for the speed requirement. Today, owners and operators are keen to reduce fuel consumption to decrease operational costs. So far a variety of methods for conducting and analysing speed/power trials have been used by shipyards. With the assistance of the Sea Trial Analysis-Joint Industry Project (STA-JIP) and ITTC, the new IMO EEDI rules to reduce CO2 emissions have resulted in clear, pragmatic and transparent guidelines for the reliable speed/power assessment of ships worldwide.