Excessive Acceleration Criterion
The excessive acceleration criterion assesses lateral accelerations high above the roll axis, a crew injury and cargo hazard on stiff high-GM ships.
Excessive acceleration is the stability failure mode concerned with lateral accelerations at positions high above the roll axis, where a large metacentric height produces a short roll period and violent transverse accelerations rather than a capsize risk. The consequence is injury to people and damage to cargo and equipment, not loss of the ship, which makes it the only one of the five failure modes whose failure criterion is not a capsizing event.
Ships with high accommodation blocks or bridge structures far above the waterline are the exposed case, including large container ships in a stiff loading condition and some passenger ships. The paradox for a master is that the condition is made worse by exactly the parameter that improves every other stability margin, because increasing metacentric height shortens the roll period and raises the acceleration at height.
The full article will cover the acceleration mechanism and its dependence on metacentric height, roll period and vertical position, the Level 1 and Level 2 vulnerability criteria of the Second Generation Intact Stability Criteria, the direct stability assessment route, the conflict with the other failure modes over the choice of metacentric height, and the operational measures available.