27 Jul - DP in the North Sea!
Date: Sunday 27 July 2002
Position @ 1200 (UTC): Gullfaks Oilfield, Offshore Norway
Next destination: Bergen, Norway
ETD: Monday 05 August 2003
Distance to go: 80.0 nm
Total Distance Sailed: 177.0 nm (distance counter started from today)
Current Weather: Cloudy, fine and clear
Wind: S Force 4
Barometric pressure: 1007.3 mb
Sea state: Slight
Air temperature: 18.8°C.
Sea temperature: 15.3°C.
No ship's position reports are available during our stay in the North Sea since we cease doing Met observations. Map to be sourced as soon as possible.
A DAY IN THE LIFE OF AN OIL FIELD SUPPORT VESSEL
This week, RRS Ernest Shackleton has continued throughout with a program of 24-hour-a-day ROV work in the Norwegian Sector.
Here is Alan the Navigator né Dynamic Positioning Officer to give us a rundown on operations to date....
Back in DP in the North Sea I see....
Most of us arrived in Bergen on Sunday last. The few who arrived on Saturday had time to have a look at Bergen which is a town halfway up Norway's west coast. Monday afternoon saw us leaving Bergen with our new Captain, Graham Chapman in command and a very scenic 3 hour pilotage under Brysteneset Bridge through Byfjorden and finally Hjeltefjorden before an 80 mile sea passage to Gullfaks Oilfield.
Arriving there at 2300, it was just dusk. We took over from another vessel, and so we needed an exchange of documents from her and this meant an FRB (Fast Rescue Boat) trip with Wavey, to get it!
2 hours later after tests and checks of the gear, the ship was in ‘DP’ mode. Dynamic Positioning is the ship's other guise, a computerized system which very precisely controls the ship's position, and examines the consequences of a failure or a change. We need to be able to move close to oilrigs so that our ROV (Remotely Operated Vehicle) can have a look at the rig's gas/oil lines, BOP’s (Blow Out Preventer) SSIV’s (Sub Sea Intervention Valves) etc etc. Last year we inspected hundreds of miles of pipeline using the ROV which we followed using the DP system and a transponder on the ROV.
The ships position is measured very accurately (to within a metre) using:
- DGPS (Differential Global Positioning System) satellite navigation system
- Lightweight Taut Wire ( a high tension very thin wire moored on the seabed over the ships side, any movement in the ships position being detected in the angle of the wire)
- Fanbeam (an autotracking laser system. It points a vertical laser fanbeam towards a reflector and measures the time taken for the pulse to return, giving a position relative to the reflector)
- HPR this is an underwater acoustic system. It transmits and receives from a beacon using time difference between receiving elements in the HPR receiver to measure the horizontal position left or right and for’d or aft, and time delay from transmitting and receiving the signal, to measure distance to the beacon which gives the vertical position
We also need to know the effect of the elements on the ship. Windspeed is measured using an anemometer, and ship's motion using a Motion Reference Unit (MRU). This information goes into the DP system which uses a ‘Kalman Filter’ to make a mathematical ‘model’ of the ship (ie a computers view of the ship and the things that are affecting it).
The DP system then uses the ship's propulsion to hold position in a fixed spot or position relative to a beacon or a surface object. Ernest Shackleton has 2 Bergen diesel main engines and 2 generators to drive a propellor, and a combination of 5 thrusters – these are smaller propellers mounted in athwart ships (side to side) tunnels in the hull. 4 of them are tunnels as described, but the 5th is an ‘Azimuth’ thrusters; it can point in any direction, so whilst aiding the tunnels, it can also act as back up should we have a problem with the main propellor.
A DP ship will always position itself so that if the ROV looses power it will drift clear of the ship, and vice versa. However, the Shackleton is a DP2 ship; so if we loose 1 main engine or 1 thruster or 1 compass we will still hold position.
Once the ROV is in the water, a symbol appears on the navpack indicating position and heading of the ROV, so its constantly monitored by the bridge.
Wavey-Davey's Weekly Wit Spot
Davey says - 'I'm Still In Bed'
Wavey Davey remains on the night-shift this week, which means two things.
1). Great relief from his inane jokes on the Bridge and the Crew Rooms,
2). We have a surrogate 'Wavey' this week, in the guise of Antonio, the Chief Officer.....
In best Wavey Davey tradition, Antonio says -
Two snowmen are in conversation together when one says,.. 'Can you smell carrots ???'
Come back Wavey-Davey.....all is forgiven.
NORTH SEA HELICOPTER OPERATIONS ON THE GULLFAKS FIELD
Above: Helicopter LMM (Bell 214) on approach to Shackleton International Airport. Click the images to enlarge them.
During a turbulent week at London's Heathrow Airport, BAS are happy to report business as usual as their baggage handlers continue as industriously as ever on the helideck of RRS Ernest Shackleton. Above we see HLO (Helicopter Landing Officer) Antonio Gatti approaching the Bell 214 Helicopter - not to proffer Wavey-Davey jokes to the pilots, - but to ensure the doors and fastenings are all secure before the Helicopter attempts to take once again to the skies. The HLO is a big responsibility and to that end, all HLO's must undergo a 9-day basic course and obtain a recognized certificate. Many of the Ernest Shackleton's Officers have now undergone such training. Moreover, every man in attendance on the Helideck has undergone training and is a certified 'Helicopter Deck Crew' team member, this includes Helicopter Emergency Response and Firefighting.
NOT ALL WORK
When not slaving away over a hot ROV (Remote Operated Vehicle) the crew and contractors of the ship, sometimes like to relax with a mindless movie, to while away the hours between the end of the shift and bedtime. As mentioned in the annals of the pages before, the ship has a comprehensive library of videos which are kept meticulously inventoried and in the specially built cabinets in the Green Room. However, with well in excess of 200 titles to choose from, it has been decided not to purchase any more videos as there is simply no more storage space to house them. Moreover, the ship is being dragged along with technology and the introduction of DVD's (Digital Video Discs). Subsequently, all future purchases will be DVD's as we attempt to follow in the footsteps of our sistership RRS James Clark Ross, and build up an equally impressive array of titles. DVD's incidentally are much more economic on storage room !
So far we have only about 50 titles to choose from, but unlike the videos of previous years, the DVD's are not to be advertised for showing at a certain time of the day, but left to the individual to 'book out' on a 'rental-type' basis. This rental costs crewmembers no money at all, and they can obtain their very own 'Blockbusters' DVD Card on production of a current Driving License, 2 forms of I.D and slightly-used, rolled-up copy of a previous webpage !!!
Since instigating the system, there seem to have been no problems apart from the lack of titles. 'Twas ever thus... no matter how many movies they have to choose from, there will never be enough ! Videos and DVD's which are readily available to the public at large at home, are not so readily available to the Ships and Bases of the Antarctic Survey. That is why we have to arrange many 'swaps' of titles during the season to keep a 'flow of material' around the stations, and Michael Palin's 'Pole to Pole' quite literally gets to travel back and forth between the hemispheres during the course of time!
I'd like to dedicate this week's Diary to a Ms.Bennett of Dundee, for her kind 'Welcome Back' to the Shackleton webpage, and for actually admitting to have missed Wavey-Davey and his jokes this summer. Thank you Karen for your kind support, and may your taste in jokes improve with age and wisdom !
Forthcoming events: Return to Bergen upon completion of the current contract on Gullfaks Oilfields. Then we await confirmation of when the next contract will start with Stolt in the Norwegian Sector of the North Sea....as yet to be advised.
Contributors this week: Thanks to Ch.Off Antonio for standing in for Wavey Davey this week, and to 'Navs' Newman for an excellent précis on work to date.
Diary 3 will be written on 03 August and for publication on 04 August 2003