The need for 3rd party DP verification
Some ship owners/operators are a bit more averse to parting with brass than others. A case in point recently with an operator (more accurately, charterer) of a DP vessel who was miffed that the suitability and compliance folks wouldn’t accept the vessel’s DP FMEA (or indeed the Annual Trials Report) because they’d been produced in-house and not by a reputable third party. He fair threw his toys out of the corporate pram.
The folks wott caused the furore responded thus.
Very erudite m’lud. Well done.
“Please note that the Underwriters of the project would expect the client to follow best industry practice. The guidelines for DP vessels are written by IMCA so it would be expected that the client follow IMCA guidelines. The application of IMCA guidelines for DP operations is outlined in the following extract from IMCA M103 Rev 1, Guidelines for the Design and Operation of Dynamically Positioned Vessels (our underlining):
In 1991, IMCA’s predecessor DPVOA (the DP Vessel Owners Association) first published Guidelines for the design and operation of dynamically positioned vessels, prepared by Global Maritime, with the reference
103 DPVOA. The guidelines represent a practical amalgamation of current regulations, operating procedures and good practice. They have been periodically reviewed and updated and are now published with the
reference IMCA M 103 (DPVOA merged with AODC to form IMCA in 1995).
In 1994, the International Maritime Organization (IMO) Maritime Safety Committee approved its own Guidelines for vessels with dynamic positioning systems (Ref. 113 IMO/IMO MSC Circ.645), in conjunction with
implementation of paragraph 4.12 of the 1989 MODU Code as amended. Later versions of these DPVOA/IMCA guidelines have reflected the IMO document. While the IMO guidelines apply to new vessels with dynamic positioning systems constructed on or after 1 July 1994, no distinction is made between new vessels and those constructed prior to 1994 within this IMCA document.
1 Principles for All DP Vessels
Section 1 is applicable to all DP vessels. The principles should be met in full by all DP vessels.
1.1 Basic Philosophy
i) For the purposes of these guidelines a fully operational DP system is defined as one that is able to reliably keep a vessel in position when working up to the rated environment, such that the maximum excursion from vessel motions (surge, sway and yaw) and position control system accuracy (DP footprint) is equal to, or less than, half the critical excursion for the work being carried out.
ii) The DP control system should provide adequate information to operators such that any change of status of the DP system due to weather, equipment malfunction or operator action should be clearly indicated at the permanently manned position where corrective action is possible and where the limitation, if any, can be understood by operators. The indication should be such that the operator is unlikely to make a mistake in assessing the severity and effect of the status change.
iii) Safe working limits should be determined for each geographical location, expected environmental condition/force and type of task to be performed. These limits need to consider every failure mode defined by the FMEA and the likely time to restore position control, recover the divers, disconnect a gangway or riser or otherwise move clear of an area to return to a safe situation. In the case of simultaneous or close operations, failures on the other vessels also need to be considered.
Note: A ‘safe situation’ means one where the work has or could immediately cease with no serious consequences from position loss and the vessel is left in a state where operations can readily resume once the disturbance is corrected.
It should be possible for the performance and health of a system to be effectively monitored by suitably trained and experienced personnel without the need to interrupt the control process. Changing between the various modes of position control should be simple, secure and demonstrably effective in meeting the points i), ii) and iii) above.
The above basic philosophy should be applied to all the types of work the vessel is designed to undertake with careful consideration of the consequences of position loss. If continuous working means that the vessel is likely to work in a degraded state the new ‘safe working limits’ and ‘safe situation’ should be agreed by formal risk assessment. If it is not normal to continue working in a degraded status, but because of the particular circumstances on board it is considered safe to continue, then this decision should also be made after an operational risk assessment involving the key personnel responsible for the work and station keeping before a decision is made.
To help vessel owners/operators and their clients achieve the above philosophy three equipment classes for DP vessels have been defined by IMO (Ref. 113 IMO – Guidelines for vessels with dynamic positioning systems (IMO MSC Circ.645)) which recommends that DP vessels built after 1 July 1994 be assigned an equipment class.”
Use of third parties in developing FMEAs is outlined in IMCA M 103 Rev 1 Guidelines for the Design and Operation of Dynamically Positioned Vessels, Section 1.3 (our underlining):
“DP vessels have to undergo FMEA proving trials, in addition to and after, dockside testing, commissioning and owner (customer) acceptance trials. The DP system should be proven as far as is reasonably practicable in all the normal modes of operation expected during the life of the vessel. When all normal modes of operation appear to be functioning correctly, failure modes should be simulated and the results of such tests documented, by a third party.”
Independent witnessing of annual trials is outlined in IMCA M 190 Guidance for Developing and Conducting Annual DP Trials Programmes for DP Vessels, Section 5.3 (our underlining):
“The operator shall arrange for the annual DP trials to be witnessed by a competent and independent person or persons.”