Know your equipment, or at least where to find the answers

The DP equipment class 2 vessel was not on station at the time, but in standby, receiving system updates with the OEM technician onboard. The updates were being carried out within an anchorage area.

The conditions were good with two of the three generators connected in an open bus configuration, all four thrusters running and two DGNSS selected to DP.

During an update in the Follow Target Mode, the crew noticed an anomaly with joystick control. When the joystick controller was in the 0 position a command of 10% power ahead was being given.

The crew, along with the technician, consulted the joystick manual:

• Following the update, the joystick had become uncalibrated.
  
  
• The section on calibrating the joystick was located, and the crew proceeded to recalibrate it.
  
  
• This was not the first time this had occurred. When the crew reviewed the records, they found that the joystick required recalibration after every update.

This is a simple observation that could easily have gone unreported to IMCA and been dismissed as a routine update; however, much can be learned from simple events.

The lesson is not the calibration issue itself, but the need to understand system behaviour following software changes and to ensure vessel personnel know how to verify and restore normal functionality.

It is imperative that companies have a robust management of change process in place that includes an OEM software change process and an appropriate test methodology.

• IMCA M103 – Guidelines for the design and operation of dynamically positioned vessels
  
  
• IMCA M117 – Code of practice for the training and experience of key DP personnel
  
  
• IMCA HSS003 – Guidance for the initial and refresher familiarisation of vessel crews
  
  
• IMCA HSS001 – Guidelines for management of change