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.