Five DP Bulletins From October 2026: A Shared UPS, a Button Beside the Alarm, and a Calibration Nobody Isolated

Why These Five Are Worth Ten Minutes

None of these is a headline casualty. That is the point. Each one began with something that looked routine: a compressor start, a sensor calibration, a button press during an alarm, a change of UPS mode. In every case a quiet assumption turned out to be wrong. Our earlier guide to the January bulletin covered DPE 01/26; this one covers the October set, read from the full bulletin pages.

1. The Domino Effect (DP2)

The vessel was in DP alongside an offshore installation preparing for cargo operations, with all five thrusters in DP, two DGPS and a CyScan as references, 15 to 17 knots of wind and a 1.5 m swell. Two diesel generators, DG1 and DG2, were running in parallel on a closed 440 V bus at about 130 to 150 kW. The shaft generators were not being used to feed the 230 V switchboard because of an earlier governor problem.

At 18:50 and 18:52 the crew started two bulk compressors to speed up cargo tank pressurisation. At 18:54 the DG2 incomer breaker tripped. At 18:55 DG1 took the whole load and tripped too. The 230 V switchboard lost power, both steering systems failed and the vessel temporarily lost position. The emergency generator started in about 25 seconds, and at 18:59 the Second Engineer transferred supply to DG2, restoring steering. The hose was disconnected at 19:23 to 19:25 and the vessel cleared the 500 m zone.

What the bulletin found: the power arrangement did not follow the DP operations manual, CAMO, ASOG, FMEA, power management or load analysis. The intended separation between redundant groups had been lost by paralleling DG1 and DG2. And DG2 had a defect already in the maintenance system, low fuel pump pressure, that limited it to about 130 kW. Starting the compressors took the load past that limit. Because the two generators shared the load, the failure travelled from one to the other.

Take-away: a redundant system is only redundant if it is configured as designed. A known defect is a constraint on the operation, not a to-do item for later.

2. Lost in Calibration (DP3)

The vessel was running gangway operations alongside an FPSO in about 1,900 m of water, in Auto DP with six thrusters and both generators, bus ties open and two redundant groups. One radar and two laser references were selected, in good conditions (0.5 m significant wave height, 10 knots of wind).

During calibration of a vertical reference unit (VRU), the DP system lost part of its attitude reference. At 17:23:51 an Off Position Warning appeared, followed four seconds later by an Off Position Alarm. At 17:24:04 VRU 3 was selected and the position returned to normal at 17:24:10. But the vessel’s movement relative to the FPSO had triggered gangway extension alarms, and the gangway disconnected automatically. The vessel dropped to reduced redundancy (CAM Blue) and the operation was aborted.

What the bulletin found: interruption of the VRU signals during calibration made the DP system reject the affected sensors. VRU 1 was disturbed while VRU 2 was being calibrated, because the units were close together. The work was done on live DP-critical equipment, without adequate procedural controls or a detailed risk assessment, and nothing in the procedures explicitly prohibited it. The alarm history did not show which VRUs had been selected beforehand.

Take-away: redundant sensors that sit side by side can be disturbed together. Putting the sensor arrangement back does not undo what the excursion did to the operation connected to it. Maintenance on DP-critical equipment needs the vessel in an appropriate safe state first.

3. Watch What You Are Pressing (DP2)

The vessel was moving between monopile foundations at an offshore wind farm with seven of eight thrusters and four of five generators online in a ring bus. It left the first foundation in DP joystick mode, stopped outside the 250 m safety zone, selected Full Auto DP and began a slow approach.

At 10:25 an alarm sounded on the bridge wing control panel. The Master told the DPO to stop and suspend the approach. The DPO then reported that all thrusters had been disconnected from the DP operator station, and two attempts to reselect them failed. The Master took manual control and moved the vessel away, about 50 m off the foundation on the starboard side. While leaving the wind farm the Master noticed the vessel was in Backup Mode and questioned it with the team. The vessel cleared the boundary at 11:04.

What the bulletin found: tests found no DP fault. The Backup Mode selector sat right next to the Alarm Acknowledge pushbutton and was not guarded. Testing reproduced the event: selecting Backup Mode removed thruster control from the DP operator station with no alarm or warning beforehand. The most probable cause was accidental activation of the selector while the bridge team was responding to the alarm. Manual control was established within 27 seconds. A protective cover was fitted over the buttons afterwards, so the acknowledge button stays accessible but the cover must be lifted before the adjacent control can be reached.

Take-away: a confirmation step may not be enough when controls with very different consequences sit close together. Layout is a safety control. And note what saved the situation: a Master who took the manual controls within seconds instead of continuing to troubleshoot.

4. The UPS and Downs (DP2)

The vessel was transiting within an offshore wind farm in DP, with four of five thrusters, three of four generators on a closed bus, two GNSS references, three gyros and three wind sensors, in a 22 knot wind. At about 07:53 the DPO saw gyros 2 and 3 lost, with alarms from a 230 V backup power supply. The telephone system had power but could not be used.

The bridge team stopped the vessel, held it in DP1 and told the client. Meanwhile the ETO was following a recurring UPS alarm. Following the manufacturer’s instructions, the ETO enabled ECO mode to reduce demand on the unit. During the changeover the batteries did not supply the required power. A brief interruption rebooted the systems the UPS supported, including the gyros and the phones. The vessel left the field to restore DP2, all systems were back about 1.5 hours later, and the DP set-up checklist was completed before it re-entered.

What the bulletin found: the event was classed as a power distribution failure. A component failure and battery condition were underlying factors. The ETO did not tell the bridge before changing the UPS mode, because a smooth transition was expected, and the manufacturer’s instructions did not warn that the change could cause an interruption while on normal power. The event form linked the hardware failure to a lack of maintenance.

Take-away: ask what a piece of equipment supplies before you change its mode, and tell the bridge first. A change that is safe in the manual can be unsafe in the context of a live DP operation.

5. DP Drill: Consequence Analysis (DP2 and DP3)

This is a drill scenario, not an incident. It familiarises the crew with how the consequence analyser warns that a further failure would cause loss of position. Set up the vessel on full auto DP, beam-on to the environment so that more than one generator is needed to hold position, with standby generators inhibited from auto-start. Then, in turn: deselect the forward thrusters until one is left and the Consequence Analysis Drift Off Warning activates, wait three to four minutes and then remove the last one; repeat with the aft thrusters; deselect a whole redundancy group; and, on vessels with several generators, open breakers until the warning and then drift-off occur, reinstating everything after each step. The bulletin refers to IMCA Information Note 1601, DP Consequence Analysis – A Timely Reminder.

The bulletin reports expected results, not findings from an actual run. Its discussion points are the useful part: what would a further failure do once the alarm has activated, should work continue while it is active, and is the alarm covered by the ASOG and decision support tools?

The Pattern

• The assumption nobody said out loud. The ETO expected a smooth UPS changeover. Whoever calibrated the VRU expected the other units to be unaffected. Whoever started the compressors expected the generators to cope.
• The bridge was not in the loop. In two of the four events, work or a change affecting DP-critical systems was done without the bridge knowing.
• Known conditions that were not treated as limits. A generator with a known fuel pressure defect. A power configuration that did not match the manual.
• Quick, decisive manual action worked. The Master in the third event had manual control within 27 seconds.

Try the Decision Simulator

Take the third event as the Master: the console layout, the alarm protocol, the approach, and the moment the thrusters drop out of DP. It is a training reconstruction based on the bulletin. Work through it in the free Decision Simulator.

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Related Reading

• Five real DP incidents from 2026 (DPE 01/26)
• The September 2026 DP bulletins (DPE 02/26)
• Eight times a DP console did what the operator did not mean
• Hydrogen sulphide without entering the space