Abstract
Survivability of ships or offshore structures in severe sea conditions is often evaluated from their behaviours in a single extremely large wave. However, a floating body can fall into more dangerous situation when it encounters a group of several successive waves of fairly large height, which is called a wave group, with unfortunate time interval. In this paper, deterministic as well as statistic analyes of motions of floating bodies in a wave group are carried out. It is shown that the successive waves and the resultant motions can be treated as a Markov chain and thus the well established Markov theory can be applied for the analyes. Deck wetness due to the successive encounter of a floating body to a wave group is examined as one of the examples in which the successiveness of incoming waves and the resultant motions could endanger the safety of a floating body.
