PILOTING FPSO BONGA

October 15th, 2003 by JCB
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FPSO BONGA

One important aspect of pilotage work is the programming of vessels. In most ports the duty pilot routinely makes planning decisions for agents and it is all taken in the pilot’s stride as part of his duties but the responsibilities of this task are considerable and the repercussions of making a mistake are always at the back of a pilot’s mind when making critical decisions. Every once in a while the duty pilot receives a request to plan a passage for a vessel totally out of the ordinary and since such a passage will frequently involve a high media presence it is all the more important that things go right on the day. Last year the Tyne pilots received one such request for bringing in a large oilfield storage and extraction vessel for fitting out. The following is an account from John Hart Burn of the process from planning to arrival.

Link to the original pdf illustrated article:

pilotmag.co.uk/userfiles/Pilotmag%20275%20(Oct%2003).pdf

Over the years, the River Tyne has been very much involved in the energy business. At first this meant of course coal, from this there arose a rapidly increasing coastal shipping trade in coal and similarly a short sea export trade. The River Tyne was destined to become a focus of shipping trade routes which in turn also led it to become a large shipbuilding and repair centre.

Coal reached a peak in the 1930s but all good things come to an end and in the 1950s, in the dying days of coal, miners from Harton Colliery were operating at coal-faces some seven miles out under the North Sea. In the meantime the search for new energy sources had moved even further out into the North Sea for oil and gas. The River Tyne played a full part in support of survey, drilling and service vessels. Later came the construction of rigs, platforms and modules with which to exploit these fields.

The North Sea fields have now peaked with only smaller, less productive fields, lying in deeper waters remaining to be exploited.  The traditional method of production through platforms has progressively given way to the Floating Production, Storage and Offloading Unit or FPSO for short. These vessels are positioned over well heads, the oil being drawn up through flexible pipes into the vessel for storage and certain processing before being offloaded into tankers. These FPSOs may be moved by towing from one field to another relatively easily. Many of the first vessels of this type were conversions from existing large tankers and the Tyne got its fair share of this work. Nowadays the vessels are increasingly being built in the Far East and then towed to Europe for fitting out. The largest so far is the Bonga, a vessel designed for the Nigerian oil fields which arrived in the Tyne in November 2002 for fitting out.

During 2001, Tyne Pilots Ltd (TPL) were advised by AMEC Wallsend that a bare hull was being built in Korea for Shell and designed for work on the Bonga field off Nigeria. With a length of 305 metres, beam 75 metres and a DWT of 300,000 an arrival draft of about 5 metres was agreed to suit the available depth alongside the berth. Vessels of such length are not able to be swung within the Port so AMEC were given a choice of whether they wished the vessel to enter head first or stern first. AMEC opted for stern first which one suspects was down to the belief, in PR and Publicity Departments, that such a vessel, expected to proceed to sea in a blaze of glory, doesn’t look quite so good being dragged stern first!

The draft presented no problem, there being sufficient water right into the berth at all states of tide. However, with large, slow moving vessels or structures it is preferable to conduct an inward river transit with the aid of the flood tide. However, in common with many break-water ports, the Tyne experiences tidal sets across its entrance generated by the tidal stream at sea. That resulting from the South going flood stream is greatly magnified as the breakwaters are neared and this is due to the configuration of the coastline to the North and to the North Breakwater itself. Whenever  operationally possible, with such a vessel or structure, entry is arranged for slack water off the Bar which occurs at one and a half hours after low water in the Harbour. As to swell conditions this was set at 3 to 4 feet which was the requirement of the tug Masters making fast and for the head and stern sea tugs to change ends and reconnect

to bridles. It was also a requirement for the use of the boarding method, this being by way of a pilot ladder rigged over the transom and then by staircase. With a windage area in excess of some 75000sq.ft and a comparatively light draught then a wind speed of 10 to 15 knots from any direction was given as a maximum.

Towage requirement was for six tugs. The two sea tugs to take the ends with four additional tugs, one at each corner. It was advised that the two sea tugs would be required to be of a kind which would be suitably manoeuvrable for the bends of the river and of not less than 120 ton bollard pull. The shoulder and quarter tugs to be of roughly equal bollard pull but to aggregate to 200 ton to satisfy insurance requirements. As all tow lines would be secured from the main deck then the effective bollard pull of the tugs would be very much reduced from their rated pull.  An additional two local tugs, Yarm Cross and Flying Spindrift would escort the vessel as an insurance against breakdowns.  Air draught on the inward transit was not a problem and the arrival date was estimated to be August/September 2002.

TPL advised that there would be three pilots involved: One pilot on the Bonga with one each on the two sea-going tugs to act as second pilots to him. It is the convention on the Tyne for the pilot on board the tow to be in charge.

It was not until early 2002 that TPL heard again from the fitting-out yard to enquire about pilots being sent to the South Shields simulator for training. This apparently was for the pilots to be able to handle a vessel such as Bonga! It had escaped the attention of the enquirer that as far back as the seventies Tyne Pilots were involved with the launching, sailing, trials and drydocking of vessels of over 325 metres LOA and 50 metres beam!

It was therefore intimated to the fitting-out yard that such training would not be necessary. Having already paid tens of thousands to the Simulator, the yard were not best pleased. It appears that the Port, fired with enthusiasm by a company also charging tens of thousands to devise a risk management system to comply with the Port Marine Safety Code, had directed that a simulation exercise was required. Like Paul on the road to wherever it was, TPL pilots underwent an immediate change of heart upon realising that

simulation was going to be immensely more rewarding than actually doing the job itself. As it was not possible to determine which pilots might be involved in the actual job then all TPL pilots trained assiduously on as many days as could be arranged at the

simulator!! As Bonga proceeded towards the Tyne, the ETA dropped back and back. Six weeks of ideal weather were lost. The very day she put in an appearance the weather broke. After running out of neap tides with no improvement in sight she proceeded to Rotterdam for shelter. Whilst laying by in that port I believe she was struck by another vessel and required dry-docking.  Once again on her return to the Tyne the weather broke and it was not until the last day of the then neaps and with immense pressures mounting to get her in, that Saturday November 16^th opened with perfect conditions. At 0600 the Bonga and her attendant sea-going tugs were boarded some two and a half miles to the N East. Pilots involved were Ralph Sloane on the Bonga, John Hart Burn on the lead tug Smit Singapore and George Winter on the trailing tug Pacific Banner. By 0615 the four harbour tugs were made fast and the Bonga proceeded towards the breakwaters crossing the Bar at 0830. The four mile river transit was completed by 1030 making an average of about two and a half knots from boarding position to berth. From start to finish Smit Singapore was steered in auto and at no time was more than 25 ton bollard pull called for. The operation went perfectly with the pilot on Bonga not using the harbour tugs until in the vicinity of the berth. As usual, the pilots on the sea-going tugs could report having been given every support from the Masters whilst handling these vessels during transit.  Most of the Masters in these vessels have been associated with similar operations here in the past, are well used to the way in which TPL pilots operate and relationships are good. It should be noted that each pilot was accompanied by a trainee pilot and the trainee on board of Bonga was very helpful to the pilot during the berthing operation.

Due to the obstructions overside of Bonga the berth had been furnished with two dolphins which meant that positioning would be fairly critical. Whilst the sea-going tugs held the vessel in position the inboard harbour tugs were released and utilised to ‘push up’. However, since all the moorings had to come from winches ahore the operation took an inordinate amount of time. It was not until 1330 that the sea-going tugs could be released, the harbour tugs being involved for some considerable time afterwards. The job was finally completed without incident and to the satisfaction of the owners and the yard.

Soon after arrival the appearance of Bonga began to change rapidly. The fitting out commenced with the placing of many prefabricated modules on board. The lifting was accomplished by Smit’s Taks Asian Hercules which I believe is their biggest selfpropelled floating crane. One of the lifts was her personal best at about 2,800 tons. There was a pilot on board the crane for all moves and lifting operations.

At time of writing the outward passage has already been provisionally planned and despite over 20,000 tons being placed on board she will be sailing with only 5.8 metre draught. Air draught has increased to 95 metres so there is no possibility of negotiating the overhead power cables which are situated at about one mile down-river from the berth and they will have to be removed. These conductors form part of the National Grid and though provision was made when they were erected for a temporary removal, such removal is subject to a one year notice period. Although at a height of just over 87 metres above Chart Datum at lowest point of the catenary these lines have presented many problems in the past for vessels and structures wishing to pass beneath them. On occasions, surveyors have been required to monitor the heights of the conductors during a transit owing to the fact that demand surges cause heating, expansion and consequent drooping of the catenaries. Additional to the straight-forward physical clearance there also needs to be an electrical clearance.  Owing to the windage area having increased to over 118,000sq.ft.  the maximum wind speed from any direction has now been set to 10 knots. Maximum swell height of 4 to 5ft is being maintained particularly as the landing provision offered is the same as that on arrival.

Tidal requirement is once again for neap tides with the vessel leaving the berth at two hours before high water.

Tug requirement remains the same as for the inward transit. It is understood however that SNEPCO (Shell Nigeria) have engaged a different towage company so it is not yet known which sea-going tugs may be chartered.

Once again TPL pilots have been assiduously simulating and it is expected that once again the media will announce that the simulator did the job ! JH Burn

Update from John H Burn: 5/10/03

Due to strong winds the departure for Nigeria has been cancelled until 17^th October. A five day weather window has been demanded by the insurance company for departure from the Tyne and the tow down through the English Channel. As with operations off the Port there is of course the same problem in the Channel with depth of water. The catenary of the tow is such that in event of bad weather it needs to be of such length as to be in danger of snagging the bottom. It is uncertain as to which tugs will be in attendance for the job but for the two ends for the river transit the Maersk Logger and the Far Saltire are presently in Port. For the four corners it was to be Ormsby Cross and Aydon Cross (which are the two largest in the Tees) plus the Kincraig from Cromarty Firth and the Rowangarth from the Tyne. Plus two Tyne tugs Flying Spindrift and Yarm Cross in attendance for breakdowns. Waiting offshore are the ocean going tugs Wolraad Woltemade (S Africa) and the Smit Rotterdam which will be undertaking the sea tow to Nigeria.

 

2006:

The BONGA was successfully positioned in the Shell Bonga field off the Nigerian coast and is now fully operational. Full details of this facility can be found at the following link:

www.ship-technology.com/projects/bonga/