Shipwright principals are versed and practiced with the requirements and procedures to create stability booklets, lightship surveys, and inclinings.
On completion of loading of the ship and prior to its departure, the master shall determine the ship's trim and stability and also ascertain and record that the ship is in compliance with stability criteria in relevant regulations (SOLAS, Part B, Stability Management, Regulation 20)
The regulations go further and bind the vessel owner to provide stability information to the officers in charge in including:
- Tables of minimum operational metacentric height (GM) versus draught,
- Cross-flooding arrangements,
- All data and aids necessary to maintain required intact stability and stability after damage.
- Damage control information including General Arrangement Plans showing watertight boundaries, openings, the position of those controls, and corrective flooding arrangements.
To comply with these requirements a vessel shortly after the initial launch would undergo a lightship survey and an inclining test which together provides stability parameters including the metacentric height (GM), lightship weight, and coordinates of its center of gravity.
For passenger vessels at intervals not exceeding five years, a lightweight survey shall be carried out to verify any changes in lightship displacement and longitudinal centre of gravity (CG). If a change in lightship displacement is found to exceed 2%, or, the longitudinal CG changes by more than 1%, the vessel shall be re-inclined. If alterations are made to a vessel and anticipated deviations exceed the 2% and 1% limits then the vessel shall be re-inclined as well.
