‘Guidance for developing and conducting annual DP trial programs for DP vessels’ (IMCA M 190) has been published by the International Marine Contractors Association (IMCA) to describe the development, conduct and management of annual dynamically positioned (DP) trial programs for all types of vessels equipped with DP systems meeting the requirements of International Maritime Organization (IMO) equipment classes 1, 2 or 3.
Sister publication, IMCA M 191 ‘Guidelines for annual DP trials for DP mobile offshore drilling units’, sets out a program of continuous trials throughout the year. This guidance will also be applicable to mobile offshore drilling units (MODUs).
In the 1980s, DP systems onboard vessels were often tested many times during the year and the time required for this frequent and repetitious testing was costly and inconvenient for both vessel owners and their clients. In addition, the frequent testing increased the risk of equipment damage.
In 1991, vessel owner representatives met oil company and government representatives to discuss and rationalise the auditing and testing of dynamically positioned vessels. This resulted in the development of DPVOA[i] guideline 112 UKOOA Part 2 – ‘Guidelines for auditing vessels with dynamic positioning systems’, which was published in 1993. The rationalisation process continued and was enhanced with the production of IMO Maritime Safety Committee (MSC) Circular 645 (IMO MSC/Circ. 645) which was adopted in 1994. This IMO circular requires annual testing of all important systems and components of a DP system to ensure that it is maintained in good working order and to document the vessel’s ability to keep position after single failures associated with the assigned equipment class.
Since then, the concept of an annual DP trial supplemented by much shorter field arrival trials has been recommended by IMCA as a means of demonstrating that the vessel is fit to carry out DP operations appropriate to her DP equipment class.
In 1997 IMCA produced IMCA M 139 ‘Standard report for DP vessels annual trials’. This template has been widely accepted and is used with few modifications by the vast majority of vessel operators who choose to adopt IMCA guidance. IMCA M 139 has been updated to reflect the guidance in the new document.
Annual DP trials are only one part of the overall process used by clients to audit and accept DP vessels for various scopes of work and used by vessel owners/operators as part of their vessel assurance and management. Guidance on the overall process is described in 112 UKOOA Part 2.
All of the major classification societies, as well as IMO, have requirements for annual surveys or tests of the DP system; however, guidance as to the specific content of such surveys varies in its detail.