Improving offshore safety is the main aim of a new guidance document issued by the International Marine Contractors Association (IMCA) for jack-up barges used in the offshore renewable energy market.
According to the IMCA, an increasing number of its member are becoming involved in the offshore renewables sector which has led to the publication of Guidance for the Positioning of Dynamically Positioned (DP) Jack-up Vessels on and off the Seabed (IMCA M223).
The association has also released an updated version of its information note The Inspection and Auditing of Manned and Unmanned Barges.
“The aim of IMCA M223 is to provide the owners and operators of DP jack-up vessels with guidance to create procedures for going onto and leaving location,” explains IMCA technical director Jane Bugler. “A DP system interfaces with the vessel’s propulsion systems to hold the vessel in position against external forces (such as wind and waves) that are acting to move the vessel.
“For DP vessels with jack-up capability – when a vessel moves into position on DP but intends to undertake the work on location as a jack-up vessel – there can potentially be excessive stresses induced into the legs during the transitional period from being on DP to ‘leg touchdown’ to soft pinning of the legs. The first leg contact with the seabed will restrict the vessel’s motion which may indicate a position error to the DP system. This could the lead to an increase of thrust of the vessel’s positioning propulsion systems and consequently may impart these excessive stresses on the legs.”
IMCA M223 includes a section on risk analysis that covers vessel characteristics, environmental conditions and loading, site specific assessment integrity, and DP specification and performance). The guidance also cover company procedures, vessel procedures, and information for each location and procedures for a DP jack-up vessel moving onto and off a location.