At 9.02 the phone rang. Within twenty-one minutes Tonny Moeller had set in motion an unplanned project which would consume the rest of his and colleague Karsten Haegg’s day and end by putting the mind of the Maersk Deliverer’s OIM, Adam Kobren at rest.
Semi Questions Fully Answered – The $15million Phone Call
If the weather had improved he might have taken his vintage sports car out for a Saturday run, but the occasional showers at least had kept him from hedge-cutting duties. At 9.02 the phone rang. Within twenty-one minutes Tonny Moeller had set in motion an unplanned project which would consume the rest of his and colleague Karsten Haegg’s day and end by putting the mind of the Maersk Deliverer’s OIM, Adam Kobren at rest.
Maersk Training has a long and growing relationship with Maersk Deliverer, one of Maersk Drilling’s expanding fleet of semi submersibles, and the connection was about to be strengthened over the next ten hours. The semi’s crew, both sets, had new building training at Svendborg and some had undertaken dynamic positioning training in preparation for this particular job. In shallower waters than she’d been designed for, the semi-sub would be anchored for the first time whilst working, thereby saving on thruster fuel.
Operating off the Angolan coast what Adam Kobren urgently needed to know was what the consequences would be of a mooring failure, such as an anchor cable snapping. Also at what point should they run DP or put it on standby. He turned to the person he thought most likely to ‘know someone who can’, Jens Christian Rise, Maersk Deliverer’s rig manager and he turned to the people he thought best equipped to provide an answer. He picked up his mobile – this was potentially the multi-million dollar Phone-a-Friend question.
Seven and a half thousand kilometres away from the rig, Tonny and Karsten meet up at MOSAIC fed with the information that the semi-sub was in 271 metres of water, rig depth 20.5 metres and 52410 displacement, all eight anchors and chains set up as in the mooring analysis, each with 159 tons and no current. Over the next few hours they would simulate a variety of different conditions, monitoring the effect on the semi-sub before forwarding a list of conclusions to Adam.
A total of seven scenarios were programmed into the computer and monitored, but the most dramatic findings came with the computers’ contradicting a long held miscalculation. The figures in the mooring analysis for what is called The Ten Year Storm showed with wind at 33 kn a wave height of 1.22 metres, however the simulators put the wave height at four metres.
‘So in the end of the day, what you did down there (in MOSAIC) convinced the client that we should just be in moored mode and not use the DP system before we have made a further risk analysis. So in the end of the day it allowed us to continue operating,’ said Jens Christian Rise.
And in money terms? ‘Ooh I mean it is about $½million a day and we could take a month to make a FMEA – Fail Mode Effect Analysis – so 30 times $½million, we are talking $15million,’ he added.
‘It really impressed the client that first of all we have that kind of technology in our company. Nobody I know of has these kind of simulators and the fact that we could have this done in less than one day is a great service to be able to provide to our clients,’ said Jens Christian who pointed out that competitors seeking riser analysis would normally pay up to $70,000 for such information.
Sourcing actual plans
Since MOSAIC can call up the actual architect drawings of Maersk Deliverer, Tonny and Karsten were able to produce findings with guarded accuracy. In their recommendations for using DP they forwarded the following:
The DPs in normal Auto position is not designed to operate in DP while moored wherefore this operation mode should be carefully considered. If Position Reference system drifts this might cause high thruster force.
According to above simulations the DP model reacted quite quickly with thrusters disabled and enabled by DPO when mooring broke, and we believe that this is a safer operation mode than using Auto position mode with thrusters enabled.
All in all it wasn’t a wasted Saturday for Tonny and Karsten, they received thanks and feedback from the semi, but more than that – they had further proved that in MOSAIC they have a unique tool which can contribute to safety beyond the bounds of training courses.
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