Time varying wind effects have been included in a number of the commonly used stability criteria for many years. The heeling work-righting energy type of criterion used by many regulatory bodies hypothesizes a heeling moment generated by a wind of specified strength acting on the ships profile area. The stability requirement is then expressed as a minimum required ratio of the area under the righting moment curve to the area under the heeling moment curve starting from zero heel angle. This heeling moment area is just the work done by a heeling moment that is initially zero when the ship is upright, then rises instantly to its maximum value before the ship develops any appreciable heel. Thus it corresponds to an increase of wind strength that is a stepwise function of time. The maximum dynamic heel angle is reached when the potential (righting) and kinetic (heeling) energy are equal.