Once little more than powered barges, a whole new generation of highly efficient work boats ply the Seven Seas
Although it is arguably more crucial to our well-being than monster tankers and container ships, the hard-working, vital offshore support vessel gets little respect. There is hardly a major port city in the world that has not been visited by these vessels, but their history has been neglected by a maritime press that glorifies sexier, more celebrated ships such as aircraft carriers, guided-missile destroyers, strategic-missile subs, oil tankers, mega-container ships, classic passenger liners, blockhouselike modern cruise ships and ferries.
To a large extent, offshore drilling counteracts the terrorist threat to shore-based overseas oil resources, even though it has some security issues of its own. Additionally, it supplements the diminishing or uncertain oil supply from domestic and friendly land-based wells. The ships that serve these structures underpin the entire industry.
The offshore oil rigs, drilling platforms and the business end of the operation get all the glory, but the hardy ships that link these artificial islands to the mainland in all weathers are the forgotten heroes. I am talking about a whole family of robust little vessels that replenish and reposition the drilling platform “artificial islands.” Support vessels play a vital role in the search for reserves of offshore oil and gas, and subsequent production.
The offshore supply boat sector furnishes crucial lifelines to offshore drilling rigs, fixed platforms, and floating platforms. The main services provided are: 1) Delivering drilling supplies, fuel, water, and food; 2) Moving personnel to, from, and between offshore installations; 3) Towing rigs from one location to the next and placing or retrieving its anchors (modern semi-submersible rigs are secured and braced by a network of anchors, contrasted to “jack-up rigs” or fixed rigs that sink heavy concrete and steel pilings into the sea floor); 4) Providing safety and emergency response services and, 5) Supporting offshore construction projects.
It might be useful here to briefly examine the history of offshore oil exploration and production. In the late 1800s, entrepreneurs in Summerland, California, began exploiting the numerous springs of crude oil and natural gas that dotted their landscape. These early oilmen noticed that the wells nearest the shoreline were the most productive. In order to exploit the near-shore wells, in 1887, one innovator hit on the idea of setting up a wharf and erecting the drilling rig on it. The first such coastal water rig extended about 300-ft into the ocean and, by the early 1900s, industrialists had built several more wharfs, the longest extending some 1200-ft into the Pacific.
By 1910, the widespread use of the internal combustion engine, especially for automobile propulsion, greatly accelerated the consumption of gasoline and new drilling technologies furthered exploitation of oilfields though the 1920s and 1930s.
By the 1930s, drillers were developing giant oil reservoirs in Venezuela’s Lake Maracaibo and this project became an inspiration to those developers who had faith in offshore oil near US shores.
Several attempts to develop Gulf of Mexico oil had been made before the war, most of them unsuccessful. One operation, however, spearheaded in 1937 by Pure oil Co. and partner Superior Petroleum, did pay off. It was conducted on a 33,000-acre State offshore lease near the town of Creole in Calcasieu Parish about 20-mi east of Cameron, Louisiana. The companies built a 30,000-sq-ft wooden platform in 14-ft of water. Though the platform was erected less than a mile from dry land, its mere existence set a record for both platform size and water depth for the Gulf.
As America made the transition from a wartime to a peacetime economy in the late 1940s, the petroleum industry was encouraged by the end of government controls on crude oil prices, while States began disputes among themselves and with federal authorities over offshore water-bottom ownership. It was during this period that the industry met such challenges as underwater exploration, weather forecasting, tidal and current prediction, drilling location determination and offshore communications.
Apparently, it was Soviet Russia who was first to develop the offshore oil platform in 1947 – the oil Rocks, called Neft Dafllar in the Azerbaijani language, lying 35-mi offshore in the Caspian Sea. Only snippets of information leaked out concerning this revolutionary development. Given the veil of secrecy surrounding Stalinist Russia, it had little or no effect on the development of oil drilling platforms elsewhere, but is an interesting phenomenon nevertheless; and it enhanced the old USSR’s mania for achieving technological “firsts” to trump the decadent capitalistic west.
In 1947, when the oil industry first dipped its toes into the greater Gulf of Mexico off Morgan City, Louisiana, companies were so eager to find where the oil and gas was buried that they used almost anything that would float to get out there – old Naval vessels, lashed together barges. As long as it didn’t sink, they used it.
Once they were out there, these Gulf pioneers approached drilling the same way they did land drilling carrying equipment and parts to the site where they built the derrick and drilled their well. They then dismantled the rig, floated their boats and parts to a new location, and started all over again. All supplies and workers were stowed on support boats anchored next to the rigs.
It was a costly, time-consuming process and it wasn’t much fun. All the Gulfs men agreed there must be a better way to drill a well offshore. They just didn’t know what that better way was.
Despite the unprecedented difficulties encountered, in 1947 the Kerr-McGee Corporation managed to drill the first American well from a fixed platform. Its improvised barge and platform combination, incorporating de-motorized war surplus landing craft, comprised a major step forward in drilling-unit design for offshore employment. Besides, although it sat on tidelands, it was touted as the first “out of sight of land” well, about 10.5-mi from shore in around 18-ft of water Nevertheless, this was in bayou and swamp waters, therefore technically not open-sea based.
By 1949, eleven offshore fields were found in the Gulf of Mexico with 44 exploratory wells. However, these were more or less stationary devices based on the Kerr-McGee model. When the well went dry or the drilling rig needed to exploit newly discovered fields, the whole shebang had to be dismantled and carted piecemeal to a new site, or a new platform had to be built from scratch. In either case, this was hardly cost-effective.
However the real breakthrough occurred with the arrival of Mr. Charlie, the first “submersible ” and mobile operating offshore platform that could function in the ocean, as opposed to tidelands. Later rigs modeled on Mr. CharHe would comprise a semi-submersible (anchored) transportable class. This rig was designed by Alden J. “Doc” Laborde, founder of Ocean Drilling and Exploration Co. (ODECO) in New Orleans. The rig was capable of drilling wells in water depths up to 40-ft.
Laborde came up with a plan to put the entire drilling operation on a transportable barge that could be floated to any location. Water would be pumped into the barge to sink it. When it was resting on the bottom, the barge became a stable platform from which to drill. When they were finished drilling, the barge could be pumped out, re-floated, and transported to the next location.
Mr. Charlie was built in 1952 and finished in 1953. In 1954, it was employed by Shell oil Company, drilling a new field in East Bay, near the mouth of the Mississippi River. In the face of the doubts of offshore industry professionals, Mr. Charlie performed just as anticipated and went on to drill hundreds of wells for every other major oil company operating in the Gulf. Although the offshore industry was born in the tidelands surrounding Morgan City, Louisiana, Mr. Charlie allowed it to cross the threshold of the Gulf of Mexico proper and to be exploited on the high seas in all climates and all locales.
After noticing the enhanced stability of submersible rigs when they were only partially submerged for relocation, Laborde designed and constructed an improved model the first purpose-built semisubmersible rig, Ocean Driller, in 1964. This was the prototype of more weatherly, hence, safer platforms allowing the rigs to pursue new discoveries extending hundreds of miles from a land base.
Thus, it was in the Gulf of Mexico that the first “offshore” structures were built and it was from here that many of the designs – and certainly the experience – for the more challenging and ambitious North Sea offshore industry derived.
As the rigs and oilfields moved further offshore, it became apparent that the makeshift tenders servicing them – specially adapted fishing vessels/shrimp trawlers, motorized barges, Naval yard service craft, war surplus tugs and LCTs (tank landing craft) – were but a temporary solution to setting up reliable all-weather shore-based logistic links between the rigs and the coastal stations.
The most-common vessel pressed into service was the Louisiana shrimp trawler. Typically these vessels had a large open work deck aft to handle the trawls and nets, roughly 2/3rds of the hull length while the pilothouse and crew berthing was located at the bow. They were relatively small, usually ranging from 50- to 85-ft overall. It soon became obvious that these boats were only temporary expedients.
The era of the purpose-built offshore support vessel commenced in 1955 when a group of investors, once again led by the Laborde family of New Orleans, pioneered the development of the first offshore service vessel tailor-made to support the new and growing offshore oil and gas industry. It was Doc Laborde who drafted the concept, although he was neither a marine engineer nor a professional sailor.
Laborde’s offshore experience had convinced him that there was a requirement for a specially designed vessel to serve and supply the growing number of offshore oil rigs off the Louisiana and Texas Gulf Coast. Rigs had to be supplied with drilling mud, cement, water, spare parts, groceries and people, all of whicb required transport. While there were plenty of surplus Navy vessels, fishing boats and tugs, as noted, they just weren’t suited for the work. With such co-opted craft it was cumbersome to moor up offshore to discharge cargo, maneuver and manhandle the cargo using gear originally designed for fishing trawls.
Laborde came up with the concept for a unique vessel with a long, flat aft deck to serve the rigs, thereby moving the pilot house and accommodations well forward. Since the shrimpers had a suitable layout, Laborde’s concept was essentially a refinement of these trawlers. His designs were based on sketches on lunch bags, polished up by marine draughtsmen.
Although the shrimp trawlers were familiar to those in the offshore drilling field, the same configuration applied to the oil rig supply vessel seemed weird at the time. They resembled sea-going pick-up trucks and the appellation stuck. Laborde soon decided that he needed a new company to handle this new boat business, so he and a group of investors formed the new company that eventually became Tidewater, Inc.
The innovative ships would be built by Alexander Shipyard in New Orleans. Alexander Shipyard was a small shipbuilder since before WWII, and a pioneer of the offshore industry, building not only the Breton Rig 20 (the world’s first movable offshore drilling barge for protected waters, designed in 1948 to operate in depths up to 20-ft) and Doc Laborde’s early submersible rigs but also these first supply boats for Tidewater. The shipyard would furnish a pilothouse, a used engine and some other equipment salvaged from various tugs and fishing vessels that they had on hand and patch them onto the hull designed by Laborde.
The first boat, the Ebb Tide, cost about $125,000 to build. When it came out of the shipyard, it went to work for Shell Oil. Shell was pleased with the vessel’s performance and asked for a second similar boat, so Laborde ordered a sister vessel, Rip Tide.
Both of these vessels were only 127-ft long and had a gross registered tonnage of around 150tons, quite small by today’s industry standards, but considerably larger than the work boats previously pressed into service. A few years later, the Tidewater boats were still only about 136-ft long overall and just under 200-gross tons.
These very earliest ships were provided with A-frames on the stern in order to handle anchors and a small roller in the center allowed the wire to be paid out. Some on the other hand had no A-frame and were unable to pull the anchors onto the deck at all. It’s commonly believed that the first time a ship pulled an anchor onto the deck over the roller it was an accident.
From that first vessel, other vessel designs followed – anchor handling towing supply, towing supply and supply vessels, specialty boats, offshore tugs and crew boats, to name a few.
Collectively, the boats did and still do – transport people, equipment and supplies between mainland locations and various offshore installations. They also tow and position mobile drilling rigs, assist in a variety of offshore construction projects and aid in a number of specialty services, including cable-laying and threedimensional-seismic work.
After a few years, the rigs were drilling in depths between 300- and 330-ft, tripling the depth of the early wells, but this depth is dwarfed by the newer fields such as the North Sea, West Coast of Africa, etc. In the early days, 20-mi out was regarded as being “far offshore,” then, by the late 1960s, rigs were sited at 100-mi plus, and now the rigs go wherever there is oil, regularly 500- to 1500-mi from the nearest piece of land.
The Tidewater-developed boats were designed with the sea conditions in the Gulf of Mexico in mind. While the area is notorious for hurricanes from late-July through October, the usual sea state is rather sedate relative to other sub-sea oil fields. The Tidewater-inspired vessels were not sufficiently robust to stand up to the North Sea and this became critical in the early 1970s when offshore oil and gas development in the Norwegian and British sectors of the North Sea got under way and it became apparent that more seaworthy and effective support vessels were required.
The Tidewater-inspired boats lacked the freeboard aft necessary for working in turbulent seas and the forecastle was insufficiently tall to shelter this aft work area when green water was shipped over the bow. Often the uncovered work deck was awash, being mere inches above the waterline and the hands mustered for duty would be wallowing in waisthigh water on steel decks slippery as ice. Further, the funnels were stubby and located in the aft third of the vessel outboard, near the bulwarks. In such an exposed position, heavy swells could send water cascading over the work deck and swamp the funnels resulting in engine shutdown – a quite hazardous situation while in close proximity to the rigs. Bolt-on towing gear was situated aft where it was also exposed to breaking seas. Further, there were no stern controls for anchor handling. The engineer simply sat on a tractor seat down on main deck near the towing winch (later, all winch controls were situated in the aftlooking portion of the wheelhouse, enjoying protection from the elements as well as excellent visibility). The winch was controlled from this uncovered station in the stern.
Thus, in the experimental period of offshore vessel operations, there was little communication between Master and Engineer during anchor handling; but fortunately the anchorhandling crew knew their jobs well and made up for the lack of interaction with instinct and experience. Further, these old boats lacked bow thrusters and the joystick controls essential to maneuvering in tight quarters, having only the standard old wood helms, traditional wheels that would be familiar to sailing masters on the clipper ships. Navigation equipment was nil, the helmsman guiding on existing rigs to fix his position. This usually sufficed when operating only 20- to 30-mi out.
In 1959, an exploratory/experimental well drilled at Ten Boer near Groningen, Netherlands, was deepened and discovered a significant gas deposit. Appraisal and development wells over the next few years brought the realization in 1963 that the Groningen field was not just “economic, ” nor even merely “big,” or “large,” or “giant,” but was an “elephant” field of huge potential. Given that, extending exploration into adjacent areas was an obvious decision. The story of how the first North Sea fixed platform rigs were erected in the late 1960s is an epic of fortitude and engineering savvy.
The British made the first steps from the Gulf of Mexico designs to a type of ship which was specifically planned to deal with the rougher waters and more-arduous tasks of the North Sea. The funnels were moved from outboard of the after deck to a position immediately aft of the bridge and the winches were enclosed and powered by electric or hydraulic motors, rather than standing on the after deck, with a diesel engine providing the power. However, the British designed ships, while serviceable for the preliminary exploitation of the discoveries in the southern portion of the North Sea, were not quite up to the more-arduous conditions found in the more-productive fields in the North Sea’s stormier northern sector between the Shetland Islands and Norway.
Ulstein Trading (UT), a Norwegian firm, used knowledge gained from designing fishing vessels for such extreme conditions to develop improved types of offshore support vessel that could stand up to the rigors of the exposed northern seas. The first vessel, the UT-704 anchor-handler Stad Scotsman, was ordered in 1974 by the shipowner that is today Farstad Shipping.
UT had analyzed in detail both the requirements of the emerging North Sea offshore support market and the existing fleet, talked to Norwegian owners experienced in operating fishing vessels in hard conditions, and recognized that here was the opportunity to do a better job.
The goals were a higher service speed, good sea keeping under tough North Sea conditions, safer working conditions, more comfortable crew accommodations for long, exhausting weeks at sea, and a bigger load capacity, particularly with respect to cargo carried on deck. A key requirement was that vessels should come under the 500-GRT (gross register ton) mark under the existing tonnage rules, since this had a major impact on manning scales and harbor dues.
By the end of October 1973, plans and specifications had been drawn up and the UT way of thinking rapidly captured the attention of ship owners, who did not hesitate to place contracts to have vessels built at shipyards in Europe and Scandinavia.
The first UT-705 supply vessel went into service in 1974, and the first UT-704 anchor handling tug supply vessel (AHTS) in 1975.
The UT-704 is probably the mostprolific supply vessel type ever built, and may only be exceeded in numbers as a ship type by the American Liberty and Victory ships built during and after the second World War, a total of 91 having been built all over the world between 1975 and 1987. Although there have been successful parallel and subsequent offshore ship designs, the UT-700 series and its offshoots continues to serve as the industry model.
Accommodation was Spartan by today’s standards, the winch being set well forward between the funnels giving a clear deck area of 124-ft by 36-ft.
The UT-700 series spun off nine basic designs in the 1970s and ’80s. Principal particulars are for each of the nine are as follows (tonnage is in deadweight/displacement measure and overall length is shown in meters and feet in parentheses):
UT-704, a 65m (214.5-ft), 1800dwt, anchor handling tug/supply vessel;
UT-705, a 80.77m (266.5-ft), 2450dwt (open) pipe carrier;
UT-706, a 68.5m (226-ft), 2500dwt, (open) platform support vessel suitable for pipe carrying and which can have a hull 40-ft longer for carrying additional pipes;
UT-707, a 104.4m (344.5-ft), 4000-dwt, (summer) diving-support ship;
UT-708, a 67.7m (224ft), 1050/1950-open/closed dwt, anchor-handling tug/supply vessel;
UT-711, a 53m (175ft), 900-dwt, a/h tug/supply vessel;
UT-712, a 75.5m (249ft), 3000-dwt (max.), a/h tug/supply vessel;
UT-713, a 59m (195-ft), 1300-dwt (on 4.6m draught), platform supply vessel; and
UT-714, a 58.6m (193ft), 1700-dwt (max.), a/h tug/supply vessel.
The UT-704 seemed to have combined all the possible requirements for offshore anchor handling and supply operations in a single vessel without sacrificing anything. Some of the Smit-Lloyd and OSA ships of the period were superior in engine power but invariably they had less available deck space and, in the case of the Smit-Lloyd vessels, the master was still required to stand at the controls. The majority of the British ships of the period were dimensionally smaller, and generally lighter in construction. Indeed all these companies seemed wedded to their designs, which in a way is not surprising since they were generally subsidiaries of deep-sea ship owners whose trademarks were often the actual shape of the ships. It was therefore against their whole philosophy to accept a standard type with no sign of their personal imprint.
Powered by two main engines producing some 7040-bhp (brake horse power), she was fitted with a 500-hp bow thruster giving her incredible maneuverability when weighed against to her peers. Other improvements included winch control from the bridge – as noted above, on many of the older type of vessels this was sited away from the wheelhouse, often in US-style “dog houses.” Visibility was additionally improved by furnishing superior surveillance of the working deck, a factor that contributed to safety as well as to cargo and anchorhandling/towing operations.
With a very useful bollard pull (measure of useable towing capacity) of some 80+ tons and a clear after deck of 124-ft by 36-ft width, built to take a cargo load of some 850-tons with a strength rating of 5-tons per square meter on wooden sheathed decks that provided crews more sure footing and curtailed cargo shifting, she provided her owner and charterers with a useful all-round capability.
With the 704’s semi-enclosed hydraulic towing winch, the “bolton” winch pack was outmoded. This vessel had begun to display the multi-task, all round vessel type able to provide everything required offshore by rig owners. Charterers also liked the design – it could not only supply a semi-sub drilling rig wildcatting for oil with all it needed but could then assist in raising its anchors and in towing it to a new location.
Anchor-handling operations are often on-going, in all weathers, and once started, cannot be interrupted. The usual pattern is eight anchors for a semi-submersible drilling rig and the operation is carried out by – usually – two vessels. Charterers quickly realized that the new design was a costeffective type to charter, being available to them “on demand,” and able to fulfill all of the requirements in one vessel rather than having to charter a tug in when a rig needed to relocate as well as continue to pay a supply ship to stand-by as the rig move took place.
A spin-off from the British automotive giant, Rolls-Royce Marine is the latest inheritor of the UT design subsidiary operations. They have been spinning out newer designs to handle rougher and remoter sub-sea fields. Lengths approach 300-ft with gross tonnage of up to 4000 – a 50-percent increase over the UT-704 derivatives prevalent in the 1990s.
Today ships can be made as powerful as anyone thinks necessary. Typically, the recently delivered UT-741 Far Sovereign develops 27,400-bhp giving a bollard pull (practical towing power) of 280tons, and what might be termed runof-the-mill vessel models used in the North Sea, the KMAR-404 and the UT-722 both develop around 180tons bollard. They are all very large ships and essentially owe their being to the improvement in the equipment which turns the power into thrust, and the means of controlling speed and direction.
Digital Global Positioning Systems and fanbeam have helped with the task of getting a fix on the precise track required to reposition mobile rigs, and to retrieve and re-lay their anchoring systems. The positioning systems, used together with multiple thruster engines, enclosed maneuverable propellers (kort nozzles) and fine-tuned rudders, can be controlled by a driver with suitable skills to take the hazardous seat-of-the-pants guesswork out of the delicate work conducted under the shadow of the big oil platforms.
The UT-704 design has lent itself to adaptation to individual owner requirements. Offshore operators take the basic design and improve on it to produce a vessel that is specific to its owner’s business. Some example of this practice can be seen in Tidewater Marine’s 1974 Goliath Tide. At 218-ft long she produced 8000-bhp via four main engines and, in effect, derparted from US design philosophy.
Another UT-704 operator, Star Offshore, built the enhanced 704 Star Polaris in 1983 with added, better accommodation and with a superior bollard pull. This design was known as the UT-704 Mk3. With larger screws, a different profile superstructure, twin main engines producing 9000-bhp and twin work drums, the ship was to prove her worth early on when the semi-sub Pentagon 84 broke her anchor wires in extreme weather conditions. The Star Polaris recovered some 6000-ft of wire and was able to re-lay the anchor, a factor not without merit considering the conditions she found herself in.
One more vessel worthy of mention in the UT-704 Mk3 series is the Arild Viking which had a power upgrade to 11000-bhp to give her the distinction of being the most-powerful of the 704’s designs to be built.
The UT-704 proved to be such a good solid design that Star Offshore produced a variant in collaboration with Ulsteins’ known as the UT-734. This vessel is similar to the Mk3 but had been designed to be larger, morepowerful and to have better bulk/cargo carrying capacity. Three examples of note are the Star Spica, Star Sirius and the Norwegian Northern Frontier, which was built for the firm of Stobakk and Voll.
The fundamental UT-704 design can be said to epitomize the offshore shipping industry. Many of the ships are still operating today, which is a tribute to the designers and builders, demonstrating their ruggedness, given that many have spent their whole operating life in the intimidating waters of the North Sea or other exposed areas off Africa’s western coast or in Southeast Asian waters.
Thanks to Bob Crutchfield of Panama City, Florida, who used to crew on the early Tidewater boats. Bob provided the author with a wealth of information as to how they functioned plus some illustrations of early vessels. Other information was furnished by an online article by John Griffiths in the UK and from the websites of the various designers and shipyards.
Copyright Challenge Publications Inc. Jan 2008
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