Official title: Guidelines for vessels and units with dynamic positioning (DP) systems Reference: MSC.1/Circ.1580, dated 16 June 2017 Issued by: International Maritime Organization — approved by the Maritime Safety Committee at its ninety-eighth session (7 to 16 June 2017), prepared by the Sub-Committee on Ship Systems and Equipment at its fourth session (20 to 24 March 2017)
Status and history
The earlier Guidelines for vessels with dynamic positioning systems — MSC/Circ.645 — were approved by MSC 63 in 1994 and gave the industry its first international standard for DP systems. MSC.1/Circ.1580 is the modern successor. Many vessels in service were built and classed to MSC/Circ.645, so both circulars remain part of the working vocabulary: a vessel's DP documentation states which one it was designed against.
Member States are invited to bring the guidelines to the attention of DP manufacturers, ship designers, shipyards and shipowners, to apply them to vessels and units with DP systems, and to use the model Dynamic Positioning Verification Acceptance Document (DPVAD) set out in the appendix.
Structure of the guidelines
| Section | Content |
|---|---|
| 1 | General — purpose and definitions |
| 2 | Equipment classes |
| 3 | Functional requirements — power system, thruster system, DP control system, cables and piping, essential non-DP systems, independent joystick system |
| 4 | Operational requirements |
| 5 | Surveys, testing and the Dynamic Positioning Verification Acceptance Document |
| 6 | Training |
| Appendix | Model form of the DPVAD |
DP equipment classes
The equipment classes describe how much redundancy the DP system has and therefore what a single failure may cost:
- Equipment Class 1 — loss of position may occur following a single fault.
- Equipment Class 2 — loss of position is not to occur following a single fault in any active component or system. Static components are normally assumed not to fail where adequate protection is provided.
- Equipment Class 3 — as Class 2, and in addition a single failure includes items that may be lost through fire or flooding in any one watertight compartment or fire subdivision.
Classes 2 and 3 are the basis on which the single-fault tolerance demonstrated by a DP FMEA and validated by proving trials is judged — which is why OCIMF's FMEA assurance framework and the MTS gap-analysis TECHOP both take MSC.1/Circ.1580 as their reference point.
The DPVAD
The Dynamic Positioning Verification Acceptance Document gives the industry one recognisable record that a vessel's DP system has been surveyed, tested and verified against the guidelines — replacing the patchwork of differing owner and charterer formats that preceded it.
Why it matters on board
Everything downstream — FMEA scope, proving trials, annual trials, ASOG limits — is ultimately argued against the equipment class defined here.
Read it alongside the Dynamic Positioning entry, DNV-RP-E306 on design philosophy, and DNV-ST-0111 on station-keeping capability assessment.