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Marine & Station Keeping
DP Control Systems
DP Control Systems are the computers that read position references and sensors and command the thrusters to hold position and heading. The Category covers DP controllers in single, dual and triple redundant forms, operator stations, back-up DP stations, independent joystick systems, DP networks and the spare cards, power supplies and switches that keep them running.
What the controller does
The controller filters position and heading from several references, compares them with the set point and calculates the force needed in surge, sway and yaw. A thrust allocation routine splits that force across the available thrusters. A mathematical model of the hull, tuned on the rig, predicts motion and holds position in dead reckoning when references drop out. Consequence analysis runs continuously in Class 2 and Class 3 modes and warns when the worst-case failure would leave too little thrust.
Configurations
| Configuration | Typical class | What it adds |
|---|---|---|
| Single controller | Class 1 | One computer, with an independent joystick as back-up |
| Dual redundant | Class 2 | Two controllers with automatic changeover |
| Triple redundant | Class 2 or 3 | Two-out-of-three voting between controllers |
| Back-up DP station | Class 3 | Separate controller in another fire subdivision |
Kongsberg K-Pos is widely fitted on drilling units, and systems from the Converteam line (later GE) and from Marine Technologies are also in service. Many rigs integrate DP with the vessel management and power management systems on one network.
Key specifications
| Parameter | Why it matters | Typical classes or units |
|---|---|---|
| Redundancy level | Must match the notation | Single, dual, triple, plus back-up |
| Software release | Decides spare compatibility and support | OEM version number |
| Type approval | Class acceptance of the product | DNV, ABS or other certificate |
| Thruster and sensor interfaces | Must match installed equipment | Hardwired I/O, serial, fieldbus |
| Network | Carries commands and feedback | Dual redundant Ethernet on newer systems |
| Operator stations | Count and location | Bridge, back-up room |
Standards and what they ask of a used system
- IMO MSC/Circ.645 and MSC.1/Circ.1580 set what each equipment class needs, including the Class 3 back-up station in a separate A-60 space.
- Class rules, such as ABS DPS and DNV DYNPOS, require type approval for the control system and witnessed testing on board.
- IMCA M 103, IMCA M 166 and the MTS DP guidance shape the FMEA and the operating set-up.
- IMCA M 190 annual trials test controller changeover, network failures and the worst-case failure.
A used controller is configured for its source rig. On your rig it needs a new hull model, thruster layout, alarm limits and consequence analysis set-up, followed by FMEA tests and DP proving trials.
Failure modes and inspection
- Hardware ageing in power supplies, cooling fans and storage media causes most controller faults. Check build dates.
- Network faults, such as broadcast storms or a failed switch, can blind both controllers. Check switch models and firmware.
- Obsolete operator station PCs and screens often fail before the controller does.
- Interface cards for thrusters and sensors are rig-specific. Confirm the exact part number and revision.
- Run a power-up and self-test, read the event logs and check that the licence key loads.
Documentation
- Hardware list with part numbers and revisions.
- Software release and configuration backup.
- Type approval and class certificates.
- FMEA and the last DP trials report from the source rig.
- Licence terms. Some OEMs tie the licence to a vessel and require a transfer.
- OEM service reports and obsolescence notices.
Integration
Match the controller's interfaces to your thrusters' command and feedback signals, to the power management system for blackout prevention and load limiting, and to references and sensors. A DP network that also carries vessel automation needs the same switch generation. Check the uninterruptible power supply arrangement, since class expects each controller to ride through a power failure on battery.
Spares, upgrades and refurbishment
Most used purchases here are spares. Cards, power supplies, switches and operator stations from a decommissioned sister rig can keep an older system running for years. Moving a complete used system to another rig costs close to a new installation in engineering, OEM attendance and trials. A refurbished system from the OEM, with new storage media and fans and a current release, suits an upgrade. Inputs come from DP Position Reference Systems, and the commands go to Thrusters and Propellers.
FAQ
Frequently asked questions
Can a used DP control system be moved to another rig?
Yes, but the OEM must reconfigure it for the new hull and class must witness the result. That means a new vessel model, thruster layout and alarm limits, followed by FMEA tests and DP proving trials. Confirm licence transfer and OEM support for the software release first.
What is the difference between a DP2 and a DP3 control system?
A DP3 control system adds a back-up DP controller in a separate fire subdivision, while a DP2 system uses dual or triple redundant controllers in one space. The back-up station takes over if fire or flooding disables the main DP room. Its own references and sensors must also be separated.
Where do spares for an obsolete DP controller come from?
Decommissioned and cold-stacked sister rigs are the main source of cards, power supplies and operator stations for discontinued DP systems. Match every part number and hardware revision to your installed system, and check firmware levels. Test each spare in a rig or OEM test bench before relying on it.
Does a DP software licence transfer with used hardware?
Not automatically, because some OEMs license the software to a named vessel. Ask the Seller for the licence terms and ask the OEM how a transfer works and what it costs. Without a valid licence, the hardware may only be usable as spare parts.
What tests does class witness after a DP controller change?
Class witnesses tests from the FMEA proving programme, covering controller changeover, network and power failures, and the worst-case failure. Full DP trials then show the system holds position with each redundancy group. The scope grows if the replacement changes the redundancy concept.
Looking for DP control systems?
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