An increasing number of members of the International Marine Contractors Association (IMCA) are involved with the offshore renewables sector and for this reason the association has published ‘Guidance for the Positioning of Dynamically Positioned (DP) Jack-up Vessels on and off the Seabed” (IMCA M223) and an updated version of their information note The Inspection and Auditing of Manned and Unmanned Barges’. Both are aimed at ensuring and enhancing offshore safety.
“The aim of IMCA M223 is to provide the owners and operators of dynamically positioned (DP) jack-up vessels with guidance to create procedures for going onto and leaving location,” explains IMCA’s 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 has sections on Risk Analysis (vessel characteristics; environmental conditions and loading; site specific assessment integrity; and DP specification and performance); Background Material (that encompasses company procedures; vessel procedures; and information for each location); and covers Procedures for a DP Jack-up Vessel Going on and Leaving Location.
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Press release, May 17, 2013; Image: seajacks