Abstract
Ships that are routinely called upon to perform demanding missions that often require operation in extreme weather environments will benefit from the development of heavy weather guidance (HWG). This guidance is intended to assist vessel operators in the selection of safe speed and heading in severe weather conditions, thereby reducing the probability of dynamic instabilities and potentially disastrous capsize events. A simplified method of estimating the encounter-dependent capsize probability based on the results of time domain simulations is outlined along with procedures to extend these estimates to fully characterize the time-dependency of the probability. Additionally, an alternative method of calculating capsize probability involving integration of the joint probability density function (JPDF) of wave height and length over a region of predicted critical waves.