16 Jun - Back to Immingham
Date: Sunday 16 June 2002.
Position @ 1200 (UTC): 56°05.0 North, 000°33.3 East. On the CATS pipeline
Next destination: Continuation of sub-survey. Thereafter back to the Amethyst Field off Easington.
ETA: Next Port of Call to be published later this month.
Current weather: Overcast but clear
Wind: Sou'Westerly, Force 4
Barometric pressure: 1009.0 mb and steady
Sea state: Moderate
Air temperature: 15.0°C.
Sea temperature: 13.0°C.
No Position Reports are available during our stay in the North Sea since we cease doing meteorological observations.
Last Sunday, we were working within sight of the beach at Easington/Withernsea, Yorkshire (or 'North Humberside' if you are of that persuasion). At 3 nm distance, you could not only see the twinkling lights of the town and the Dimlington Gas Terminal where North Sea Gas lines come ashore, but you practically smell the fish & chips sold at that remote East Coast seaside resort. Ah, halcyon days of summer days spent on daytrips to Withernsea ! There was once a branch line railway that took the day-trippers there from the City of Hull to the coast, before it fell victim to the Lord Beecham Axe when in the early 1960's lots of rail tracks were closed around the UK.
Our workscope requires the ROV to survey the gas pipelines all the way from the Offshore Installations into the shallow waters near the Gas Terminal. Hence the reason we were on DP (Dynamic Positioning) so close to the shoreline. However, problems encountered on Sunday night/Monday morning caused us to move away from our location and break off the work for the next 2 days. On the day that our sistership, RRS James Clark Ross, arrived back in Grimsby from Antarctica, RRS Ernest Shackleton steamed up the Humber Estuary to pass her by in the Grimsby Royal Dock.
In a week of Football, Football, Football, RRS Ernest Shackleton has managed to keep relatively isolated from the onslaught of the non-stop World Cup Fever that appears to be sweeping the UK presently. For the non-football supporters amongst us, it is one of the blessings of working in the wilderness afforded by the middle of the North Sea. One thing you cannot escape for long onboard this vessel, is the ever-present Davey F Taylor...
Wavey-Davey's Weekly Wit-spot
He's back. The nocturnal Davey surfaced during the daylight hours to make a sneak attack on the bridge with the following witticism and then melt away back to the shadows from whence he came !
Davey said - 'Did you hear about the Spanish Fireman who had two sons. ???'
' He called one Hosé '. ' He called the other Hose B' !!!???
(Well done Davey, you're back in true form.)
Did you know, that at first, Davey wanted to be a Doctor, ??? But he didn't have the patience !!!
Back to Immingham. The Ernest Shackleton made another unscheduled call at our favourite port of Immingham this week. Slight repairs were required to the ROV crane, and so after a good start to the program offshore, by Monday (10th) we were heading once again towards Immingham, via the River Humber. It was a continuation of the 'Nautical Hokey Cokey' as reported last week. Immingham is a busy port. During our brief stays alongside in the East Docks, we were able to view a large amount of tonnage - mostly car and freight ferries - passing in and out of the Immingham Dock gates all day long. The bulk of these large vessels dwarf even the Ernest Shackleton by comparison. They make an impressive display as they head through the lock which barely seems able to accommodate them.
The DFDS Ferry line boasts an impressive fleet of vessels and all called 'Tor Something-or-other'. They are generally of blue hull and white superstructure and can be seen disappearing one day only to return the next. I believe, being Scandinavian, that they are conducting trade over the North Sea to Denmark, Norway and Sweden. That's a lot of cars.
Our stay alongside in Immingham was only brief and by Wednesday morning we were ready to head back out to work. Our work took us back on location just off the Easington/Dimlington coastline where we picked up the survey of the Amethyst 30" Pipeline. That evening as we finished our initial tests and calibrations RRS James Clark Ross was seen steaming out of the River Humber under pilotage. At only 3 nmiles distance she was perfectly visible and we had the opportunity to chat on the VHF radio as she passed to the East of us and headed on up to Leith in Scotland and thereafter to Arctic waters for the summer. Then work commenced for us around 1920 hours and continued on apace for the next 48 hours.
Helicopters. On Thursday, the deck crew were kept busy with the advent of two helicopters. One in the morning and another in the late afternoon. This was crew-change day. Not for the regular ship's compliment, but for the Stolt Survey and ROV crews. The helicopters flew from North Denes, near Great Yarmouth and up the coast to our location off Humberside. The flight took about 45 minutes and they landed on the decks for about 5 minutes. That was all the time they would need to swap the passengers, pass their departure message and disappear off into the bright blue sky. Once all the paperwork was filed away, the helicopter operations could be forgotten till the next scheduled flight in four weeks time.
Later that night, the ship completed it's work on the Amethyst pipeline for the present and at 00.50 hours on a Friday morning, headed north to the CATS pipeline at a similar latitude to Edinburgh. More trials and calibrations were undertaken before the ROV was once again ROV'ing its way surveying more pipeline.
ROV's and ROV'ing.
A brief description of the business of Pipeline Surveying.
Further to the excellent precis of Mike Gloistein, Week 34, Summer 2000 , DPO Alan 'Navs' Newman, tries his hand at explaining the 'magic' that is Pipeline surveying.
Sunday 16th June - 0500 Hours. Only another 15 km to go on this survey of the 50 km section of the Everest-Tees Gas Pipeline. Keeping a careful check of the condition of the pipeline is an important part of the operation of any Oilfield, and although most of the North Sea is a relatively shallow 90 m, getting to the line and doing a thorough survey involves some specialist teams and equipment.
Most of the modifications made to the ship during mobilisation centred around the huge ROV (Remotely Operated Vehicle) SOLO MkII. It's amongst the largest of the ROV's weighing in at 6 tonnes and like most modern ROV's can dive to 3000 metres where the pressure is about 300 bar/cm³, in most of the world's oceans.
Apart from the ROV itself there are 3 other major components of the system. The crane, the umbilical winch, and the control module. A deceptively plain-looking blue container, all pre-fitted, and simply lowered into the aft hold on board.
Although Emergency launch and recovery is possible using only the umbilical, it is launched by connecting a standard lifting wire to the ROV via a special latch which can slide up and down the umbilical. The ROV is swung over the side using the ROV crane and lowered into the water with the lifting winch. Now that the ROV is only a fraction of the it's weight on the deck, the latch is released and after a few checks, off it goes into the depths.
Above: Left - the latch or 'bullet' can clearly been seen at the end of the ROV crane during a recovery operation, right - the SOLO MkII ROV / Crane system
It doesn't have complete freedom as it must keep the correct catenary on the umbilical - too much tension and it struggles, too much slack and the same happens. It also tends to drag the umbilical across the seabed. SOLO MkII can turn through 360 degrees (generally well within 300) but no more otherwise the umbilical can be damaged. I didn't notice ROV umbilical in the blister packs at B&Q DIY store, so 'wise is he who twisteth not thy umbilical' !
Surprisingly the ROV has negative buoyancy, which is due to the weight of the extra cameras, lights, pipetracker, sonar, gyrocompass, and 2 titanium manipulators. The manipulators can lift 100 kg and can squeeze up to 225 kg from the pincers which are not touch-sensitive (no force-feedback control) therefore 'handshake introductions' to this beast are not advised. The 7 function manipulator arm has more freedom of movement than the human arm.
The Pipetracker's 3 rectangular 'rings' are like a large metal-detector used for following the pipe when buried. SOLO also has a sonar for detecting obstructions ahead. The negative weight helps the ROV to sit on top of the 36" pipeline. Pipetracker is extended with lights and cameras for the top and both sides of the pipe (as well as an astern-view camera and another for the launch/recovery 'latch') The manipulator holds a 'CP Probe' which is 'stabbed' on top of the pipelines protective anodes. The voltage is measured between the field current cells and a reference cell streamed over the ship's side. The data is put into a formula which gives the rate-of-decay of the anode in millivolts. A reading between 800 and 1500 mV is normal, but if less, then the pipeline is being over or under-protected by the anodes. Over-protection actually does more harm than under-protection.
This can happen easily around Platforms which instead of using sacrificial anodes, have an impressed current system. It is not uncommon to get problems between the two systems.
All the pipeline work (and visual inspection) is the job of the duty CP Engineer, whose trained eye can pick out even the most conspicuous flaw on the encrusted pipework !
Author 2nd Officer Alan Newman
A Selection of SOLO ROV Photographs
Above: Clockwise from top left: The ROV, the pipeline wheels, one of the many cameras on board and the claw. Click on the images to enlarge them.
Forthcoming events: Complete the survey on the section of CATS Pipeline and return to the Amethyst Pipeline.
Contributors this week : Many Thanks to Wavey-Davey with a return to the awful jokes. And thanks to Alan Newman for his contribution with the ROV statistics.
Diary 4 will be written on 23rd June 2002 and for publication on 24th June 2002