Dynamic Positioning - Safety Alert
Please note that this is not a recent incident, but remains a relevant one as we have today been notified of a similar near-miss.
Dynamic positioning systems are as we know, becoming ‘de rigueur' for the truly innovative owner, and those Captains who use it, swear by it. Our cousins in the offshore business have been heavy users DP for several years and are the best guys to speak to for sharing practical (rather than marketing) information and often first to stumble over a significant snag.
A near-miss fatality occurred on a DSV (Diving Support Vessel) late last year, which highlights the potential for common mode failures on DP systems, and has specific implications for vessels fitted with a Kongsberg K-POS 1, 2 or 3 system.
We attach a link to the UK Health & Safety Executive which provides more detail and a case study from the Divers' Association, which is not a formal document but does give a fairly clear outline.
In summary: Whilst in DP-mode with two divers working at 90m depth, the vessel suffered complete DP communications failure, causing the vessel to drift off position, and move rapidly away from the work site in relatively heavy seas (30 knot gusts and 4 m significant wave height). As a result of the vessel losing position, one of diver's umbilicals first became snagged, and then failed. This left the diver without life support (main gas, light, suit warm water).
The vessel moved off by 240 metres, before first by manual control and then reactivation of the DP, repositioned over the dive site. Then with the other diver who had remained at working depth in the bell, they were able to rescue the other now unconscious diver.
Whilst the diver had been without gas for 24 minutes, once his helmet was removed in the bell, he regained consciousness, and ultimately made a full recovery – his fitness level, training (i.e. the decision to stay on the template), the cold water (3 deg.C) and high oxygen level of his 10 minute reserve all contributing to his survival.
The DP system that failed, was a Kongsberg system and could impact around 1,300 vessels. It is understood from the owners of the DSV that around 50% to date of the affected population of vessels have now taken the recommended upgrade. As we do not have access to Kongsberg technical bulletins, we would recommend Captains/Chief Engineers who have such systems contact the manufacturer direct.
For those on board Watkins' managed boats, on this occasion we do not require this to be circulated to all crewmembers, but please make senior deck and engineering officers aware at your next HESS meeting, and allow those who are interested to read it. I can be contacted at any time if anyone has any questions. I almost certainly won't have the answer, but will know a man who does.