Advances in technology now allows newer equipment to remain operational under harsher weather conditions. In severe weather, the most limiting factor is usually the launch and recovery system (LARS). The relative motion between the vessel and ROV becomes critical during launch and recovery. Operators want to minimize the time the ROV spends at the water/air interface – going up or down. In this scenario, the lifting cable, which is often the umbilical itself, can go from slack to excessive “snatch” loads between the crest and trough of just one wave. More advanced LARS equipment employs a motion compensation technology in the winching system that counteracts this tension spiking caused by the sea swells. The ability to safely continue operating in higher sea states before recovery is required expands the system’s “operational weather window.”
Eventually, adverse weather will limit the time that can be spent on any operation. Marine weather can be classified in different sea states. It is important that you understand the common and expected sea states that the your specific OWF will experience during all seasons. By comparing the sea state definitions to the design specification of the burial equipment, planners can assign a level of risk or probability of weather down time to the time frame in question.