Marine Operations such as pipe laying, subsea installations, heavy lifting operations, work-over operations, crane operations are extremely sensitive to metocean conditions. Wind, wave and currents from different directions and long period wave motion can cause adverse vessel response which may impair operations. Thus, without systematic sea state monitoring, marine operations sensitive to wind, wave height, wave period and vessel motion can be subject to delays, cost overruns, safety issues, and asset damage. Precise knowledge of the sea state during such operations is an essential requirement which has become more critical as offshore activities have moved into ever greater water depths, and into hostile frontier areas. This calls for a reliable and accurate on-board system for continuous, real-time wave and motion monitoring and recording.