Deadweight survey (sea trial)

A deadweight survey at sea trial is a draft survey that fixes the ship’s lightship weight, the displacement of the completed hull, machinery, and outfit with no deadweight aboard. The surveyor reads the six drafts, corrects for trim, hog or sag, and water density, computes the displacement from the hydrostatics, then deducts every measured constituent of deadweight on board (fuel, fresh water, ballast, stores, liquids in machinery) to back out the lightship. The lightship weight and its longitudinal center feed the inclining experiment and the loading computer. The IMO 2008 IS Code requires the result to fall within tolerance of the inclining-derived figure.