Extension trial

An extension trial is an additional sea trial run after a modification, retrofit, or repair that affects the parameters a prior trial certified, so the changed condition is re-demonstrated rather than the whole program repeated. Typical triggers are an engine power limitation or shaft power limitation fitted for EEXI compliance, a propeller change, a ducted-thruster retrofit, or hull cleaning, each of which shifts the speed/power relationship. The extension trial reruns the affected runs, usually a reduced set of double runs, and the results are corrected under ISO 15016:2015 and compared to the original protocol to confirm the post-modification performance and update the loading and EEXI documentation.