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  • 1 Introduction
  • 2 A Brief History of the Offshore Industry
  • 3 The ships
  • 4 The Design
  • 5 Basic Data
  • 6 Conclusion
  • 7 Contributors

This Guide tells the story of the UT 704 Anchor-handling Tug/Supply Vessel - the "Offshore Workhorse".

They have been around since 1975 and continue to provide sterling service. Today, thirty five years plus after the design took shape and left the builders slips, the UT 704 AHTS vessel continues to earn its keep in the highly competitive world offshore. They have been referred to as the 'Liberty ship' of the oil and gas logistics industry, an accolade that is not too far from fact, and - like the Liberty ship - have provided service to their owners as well as ensuring that their designer and builders continue to maintain the reputation that they justly deserve.

Built by Ulstein Hatlo - now Rolls-Royce Ulstein - the type revolutionised a fledgling industry and is the forefather of the many AHTS in service today. So great was its impact that improvements on the basic design spawned a generation of vessels that have made the company the premier ship designer / builder in its field. If any single ship type deserves a place in shipping history, then the Ulstein Type 704 is it..

This entry will attempt to illustrate the impact that this design had on the offshore marine industry - even today, as the oldest vessel of the class continues to soldier on. The type was, without doubt, a mini revolution in ship design whose impact continues to be felt today in the ultra modern ship types produced for the offshore industry, a pedigree that continues to make Ulstein designs amongst the most sought after by offshore shipowners across the world.

A Brief History of the Offshore Industry[edit]

It was in the Gulf of Mexico that the first 'offshore' structures were built. Typically operating in water depths of around 90 to 100 metres they were nothing like what is found in the North Sea nowadays but it was from here that many of the vessel designs - and certainly the experience - for the European offshore industry came.

In 1959 geologists discovered the Groningen land gas field in the Netherlands and surmised that the rock formations could well extend beneath the Southern North Sea. A year later, in 1960, gas was discovered off the east coast of the UK. Later, geologists working around Greenland predicted that the rock formations supporting oil and gas could extend to the Scottish coast. During the '60's, oil exploration in the northern North Sea began, however, success was late in coming and it wasn't until 1969 that the first 'oil strike' produced enough for oil exploration and development companies to want to speculate in the area. To stake their claim as it were, in what was to prove to be a significant chapter in the economic history of Great Britain - the North Sea Oil industry.

However, whilst the companies who came over from established fields off the US coast and in the Gulf of Mexico in the early days knew oil and had a wealth of experience drilling for it at sea, they did not have any real knowledge of the North Sea itself. Weather conditions were a factor that they had to sit up and be very aware of for the North Sea can and does produce large waves driven by winds often in excess of 180 km per hour at its worst, whilst its relatively 'calmer' cousin in the Southern sector - being shallower water - can produce a surprise or two for the unwary itself. It is, without doubt, a hard place to earn a living- something that the marine operators were to discover in a very short space of time.

Together with the US based companies who rushed to stake their claim in the new fields being discovered offshore of the UK came the owner-operators of the ubiquitous supply vessel, the 'maid of all work' that had been borne of the need to maintain, supply and service the rigs out in the Gulf of Mexico. Yet whilst the US designed ships had been adequate offshore of the US, they very quickly proved to be relatively unsuited to the far more treacherous conditions found in the North Sea.

The ships[edit]

By the mid '70's the US design had almost been usurped by one more suited to the conditions off the UK's coastline. To begin with however, the ships that worked offshore were of an almost 'standard' profile suited to, and built for, the US market. The US design could be said to be 'flimsy' in that it was not really able to cope with most of the weather conditions found offshore UK. Most US ships of that time - if not all - followed the accommodation forward, clear deck aft design that was categorised by the twin funnels right aft profile peculiar to the Gulf of Mexico. They also had minimal freeboard aft to the point - in some cases - of having the main deck mere inches above the waterline! However, those pioneering craft - despite their shortcomings - blazed a trail that is the start point for the ships we see today.

Many of these early vessels also suffered from seriously inadequate 'area of operation' design faults including major power losses brought on when seas would wash down the funnels and literally stop the main engines. They had steel decks which were not suited to the conditions found off the UK coast as it allowed cargo to slide, often affecting vessel stability. Also, in many of the earlier designs, equipment was rudimentary and extremely basic having been based on - again - the US experience. For example, a 'stand alone' diesel powered anchor winch often provided the towing and anchor-handling facilities of the ships - this could be called a 'bolt on accessory' as it was not a permanent fixture - being lifted off to allow for more cargo to be carried as and when required. Basically, it was a nothing more than a huge diesel winch driven entirely separately of the ship's main power plant. In terms of anchor handling, many ships were fitted with 'A' frames right aft as US practice had been to raise anchors to the 'tail gate' and hang them off. Anchors were rarely brought aboard. It has been said that the first time an anchor was decked it was due to being more by accident than design!

These then, were 'wet' ships and crews would spend a lot of time working in conditions that were typical of the image of the oil industry back then - basic and very dangerous. It was not unusual for operations to be spent working in water that was more often than not waist high for the deck crew, with the steel decks underneath adding to the already many risks involved..

Despite these failings, many British designed and built ships continued to follow what was the almost 'standard' US design practice illustrating, perhaps, the lack of knowledge and awareness amongst UK ship operators at that time. Yet British ship owners were also quick to learn - if they wanted a share of the offshore game they had no choice. It was the established UK ship owners that took the basic design and developed it further as a vessel better suited for the task it faced in European waters, closely followed by their neighbours in other European countries whose seas had also been found to be 'oil rich'.

At this stage of the game the UK market was dominated by the old British traditional 'deep sea' ship owner with fleets such as Cunard, Blue Star and Blue Funnel being amongst the largest operators, best known at that time under their 'offshore' names of Offshore Marine, Star Offshore Marine Services and Ocean Inchcape respectively.

Despite the freshness of the industry, shipping companies hung onto their 'traditional' image. Ocean Inchcape, for example, ran their ships with black hulls, white upperworks and green decks - the same scheme operated by the parent Blue Funnel company with the exception of the funnel colours, which in OIL's case were red with a white central banding bearing the 'OIL' logo. Offshore Marine's fleet had grey hulls, green decks and white upperworks. Funnels were buff yellow and bore the 'OM' symbol. In each case, both companies flew their parent company house flag, for example, OIL flew the distinctive 'AH' (Alfred Holt) house flag of the Ocean Group. Another well known shipping operator who appeared on the scene about this time were Harrison's (Clyde) whose vessels also had a traditional but strikingly 'personalised' colour scheme of blue hull, white upper works and red funnels. The days of the 'colourful' OSV we see today had yet to arrive, although the Norwegians had already adopted the style within their own fleets. It is understood that the Aberdeen based company Seaforth Maritime - who very quickly became a major shipping operator - were the first of the UK companies to break from tradition and paint their ships in a distinctive style - maroon hull and cream upperworks being a radical departure from tradition. Seaforth did, however, have Norwegian connections and the Norwegian side of the partnerships vessels - Stad Offshore (now Farstad) - were painted the same.

In terms of type design, the early ships were broadly similar to their US relatives in that they were accommodation forward, low working deck aft types - but funnels were now amidships and the winch had become either electric or hydraulic powered, in many cases undercover in its own separate winch room - a design factor which was common on, and 'borrowed' from, deep sea tugs. The ships still had a relatively low freeboard but their hull shape had adopted an altogether more business like look. Whilst the 'big' UK operators dominated the scene, other companies began to appear as the 'boom' attraction of the industry developed and the need for marine support became widespread. A lot of the US owner-operators began to discard their early tonnage and go in for ships whose capabilities - and appearance - began to look more European in its profile.

The Design[edit]

However, European ship owners have always looked closer to home for their ships and 'Standard' designs such as the Ulstein UT 704 started to make their mark on the industry. This Norwegian design first appeared in 1975 and was the most 'popular' of all the designs produced within the supply ship industry with over 91 vessels being built between 1975 and 1986. Initially they were built for Norwegian owners. Ulstein, having a reputation of building fishing and other vessels used to the harsh environment found in the North Sea, produced 19 vessels alone between 1975-6 for Norwegian companies and they became a 'type' which worked extremely well in terms of suitability for the very specific role demanded offshore.

The first of the UT704's to enter service was the Finnish built Skaustream owned by the I.M. Skaugen Line and built at the Oy Laivarteolisuus shipyard. Powered by two Nohab main engines producing some 7040 BHP, she was fitted with a 500HP bow thruster giving her incredible manoeuvrability when compared to her peers. Other innovations included winch control from the bridge - on many of the older type of vessels this was sited away from the wheelhouse, often in US style 'dog houses'. Visibility was also improved by giving a better view of the working deck, a factor that contributed to safety as well as to cargo and anchor-handling / towing operations

With a very useful bollard pull of some 80 + tons and a clear after deck of 124 feet by 36 feet width, built to take a cargo load of some 850 tons with a strength rating of 5 tons per m2 on wooden sheathed decks, she provided her owner and charterers alike with a useful all round capability. With her semi-enclosed hydraulic towing winch, the days of the 'bolt on' winch pack were numbered; 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 have to continue. The usual pattern is eight anchors for a semi-submersible drilling rig and the operation is carried out by - usually - two vessels. Charterers quickly realised that the new design was cost effective type to charter, being available to them 'on demand', and able to fulfil 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.

Apart from the basic innovations offered, the UT 704 design was also the first vessel of its type built with rounded quarters, allowing the tow wire free movement. Traditional tug designs, modified to include a gate over an open stern, were very much in evidence on other types of offshore supply ships and required the crew to open the 'gate', connect the tow up, and then close it for the towing operation itself. One ship - the 8000BHP Oil Hustler of Ocean Inchcape Limited (OIL) - was so fitted and was very 'heavy' in terms of workload. The UT 704 was also fitted with hydraulic pins which rose from the deck and trapped the tow wire - restricting its movement, especially in a seaway - an improvement that was not only in advance of anything yet seen offshore but which also had the benefit of making anchor-handling and towing operations significantly safer for the crews. The device, again modified, is now standard on all vessels of this type as well as on tugs. Paradoxically, the aforementioned Oil Hustler - despite being built at this time - had nothing like these items to assist anchor-handling / towing operations, perhaps illustrating how behind British shipowners were when specifying assistive technology aboard their vessels.

When Stad Seaforth Shipping - now Farstad - took delivery of the Stad Scotsman in 1975, the ship attracted great attention and provided further proof of the versatility of the design, setting almost an industry standard for ships that followed in terms of horsepower, bollard pull and cargo handling. - facts noted by ship owners who began to include the type in their fleets. Indeed, Viking Offshore had, at one time, no less than 11 UT 704's on their books! Built by Ulstein Hatlo, Stad Scotsman is still sailing today, owned by Seabulk Offshore UK Ltd named Seabulk Condor. Up to March of 2005 she was on charter to the UK MOD operating off the Falkland Islands. Modifications from the original design to date include an additional bow thruster and comprehensive fire fighting equipment enabling her to continue to compete against newer tonnage.

Over the years this design also proved suitable for many developments which included higher horsepower / bollard pull, conversion to salvage ships, salvage and towing vessels and effective conversion to stand-by / safety vessel - a fate that has been the last role for many supply boats over the years. In many ways, the UT 704 also brought forward the demise of the 'pure' deep sea salvage tug - versatility was now the key to operational success and the AHTS made a significant impact into an industry that was once the domain of the prestigious salvage tug. The UK firm of Alexander Towing's UT 704, Invincible, built in 1983 at Tangen Werft, was used not only in the offshore sector but also completed ocean tows - significantly, the tow of the barge Goliath Atlantic which was carrying the jack-up rig Zapata Heritage 13500 miles from the Gulf of Mexico to Singapore. The inroads made by vessels like this surely contributed to the demise of the traditional ocean going tug, a result of which saw established tug owners like Wijsmuller incorporate the open stern and roller arrangement in their newbuildings in order to compete.

Star Offshore Marine Services of Aberdeen had an improved UT 704, Star Polaris, built in 1983 with additional accommodation and with a superior bollard pull. This design became known - though not officially - as the UT704 Mk 3. With larger screws, a different profile superstructure, twin main engines producing 9000 BHP and twin work drums, the ship was a bold step forward for the usually conservative British shipowner - but one that enhanced their trading position considerably. Norwegian owners were not slow in seeing the versatility of Star / Ulstein's collaboration! Worthy of mention in the UT 704 Mk 3 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 ever to be built. Interestingly, she was originally ordered by Balder Offshore but they were, at the time of her launch, selling off tonnage and so she became the Schelde, owned by Dalia Shipping of Holland. She sails today as Northern Comrade of Trico. However, to look at, the UT 704 Mk 3 bears little resemblance to the original, although the pedigree is unmistakable.

The design proved to be so robustly successful that Star Offshore later produced a further variant in collaboration with Ulstein that became known as the UT 734. This vessel was similar to the UT 704 Mk 3 but had been designed to be larger, more powerful and to have better bulk / cargo carrying capacity. Three examples - the Star Spica, Star Sirius and the Norwegian Northern Frontier built for Stobakk and Voll - showed that the original design could be further and significantly improved. These vessels continue in service today - Star Spica is in service as the Dea Signal, Star Sirius is the Hua Shan and Northern Frontier sails for Swire Group as the Pacific Frontier. A fourth was constructed by Dae Dong Shipyard in Singapore for Vietso-Petro of Vietnam - the Vung Tau 01.

Other ship owners also took the basic UT 704 design and upgraded the original power-train, creating a UT 704 Mk 2 class almost by default - the major one being the Dutch company Smit-Lloyd. Known as the SL90 Class and built at the Titova shipyard in Yugoslavia they had a bollard pull of 110 tons and, via Sulzer Jugoturbine main engines, produced 9000BHP. These three vessels - Smit-Lloyd 90, 91 and 92 - also had joystick control, were fitted with Karmoy forks / hydraulic towing pins and the usual liquid and cement tank storage spaces below the main deck. They joined two Korean built 'XX' Class vessels in the Smit-Lloyd fleet - the lower horsepower Smit-Lloyd 118 and 119. This pair, built by Samsung Koje in South Korea, had a bollard pull of 82 tons and were powered by twin main Polar Nohab engines of 7200 BHP - basically, a standard vessel.. The Smit Lloyd 90 soldiers on as the Boa Princess whilst the Korean built sisters sail as Seabulk Cormorant (ex Smit Lloyd 118) of Seabulk International and Smit Lloyd 119 as the French flag Carangue of Abeille International, providing anti-pollution duties as part of her remit.

The image below is an original illustration of Smit-Lloyd 90 by John Griffiths.

Vehicle Bulk carrier Ship Boat Cargo ship

The design was now being constructed all over the world - being built in Canada, Poland, Korea, Singapore, Finland, Australia, Italy, Yugoslavia, Malta - and for owners as diverse as Russia and China, whose own offshore industries were beginning to develop and who quickly realised the potential of the UT 704. For example, the British company Offshore Marine took delivery of the Dee Shore built by Astilleros de Santander SA in 1976. This vessel, one of the original UT 704 designs, was last in service with Tidewater Marine ( Pan Marine, a Brazilian subsidiary ) as the Cruz Tide. According to Equasis, she remains in existence.

The image below is an original illustration of Dee Shore by John Griffiths.

Vehicle Boat Ship Watercraft Naval architecture

Indian and Chinese yards also built the smaller but identical looking UT714, whose principal role was designed as a multi-purpose type (in the same manner as its larger sister) for work in shallower waters and at a more cost effective price for cash strapped economies. To look at they bear an almost carbon copy profile though their dimensions are slightly less and power is around the 6000 BHP mark. One current example of this type is the Field Express of Vroon Offshore BV. Built by Jiangnan Shipyard, Shanghai, China, with a length of 55m, beam of 13m and a draft of 5m, and of 1299 GRT She was delivered to Solstad in 1984 as the Normand Sky, .

1986 was supposedly the final year of construction for the UT 704. Two, built for the Chinese National Shipping Company, were built by Malta Drydocks and that should have been it - but then there was the Ballantine. Purchased as a hull by Balravie Shipping of Aberdeen, she was contracted to Hall Russel (Aberdeen) for completion but both the owners and Hall Russell filed for bankruptcy shortly after she was purchased, thus leaving the vessel still in the hull only form and bearing the name Ballantine. Originally built ( as a hull )in 1983 by Sarpsborg Mek, she was not fully completed until almost 10 years later. The hull was sold to Berge Partners in 1991 and laid up in a Norwegian fjord with plans for completion as Lancelot Rover. However, she became the Torbas, having been purchased by Remoy Management from 1991 to 1998 and then purchased by Havila Supply and re-named as the Havila Charmer. She now sails for Bourbon as the Bourbon Charmer. Alas, only her hull bears any resemblance to the original design but even that has been modified so that the vessel appears totally different. She does, however, bear the distinction of being the last of the class launched as an UT 704.

Basic Data[edit]

UT 704 Dimensions: (Based on Smit Lloyd 90 - other individual vessels varied slightly)

  • Length: 64,76m
  • Breadth:13,82
  • Depth: 6,90 m
  • GRT: 2914,2
  • Main engines: 2 x 16 cylinder Sulzer Jugoturbine type 16ASV25H 16ASV
  • Power: 8640BHP
  • Bollard Pull: 110 ton .

Dee Shore (for comparison)As above but main engines Alco Engine Inc. Type: 18V-251-F 7040 BHP


If any vessel can be said to exemplify the offshore shipping industry then it has to be the UT 704. Many of the ships are still operating today, which is a testament to the designers and builders to their ruggedness, given that many spent almost their whole operating life in the hostile waters of the North Sea. When one considers that boats built in the 60's, 70's and 80's were built only for a 15 to maximum 20 years of economic life, then the longevity of this type says a great deal about the knowledge of the builders and the foresight of their vision.

Throughout the industry, the design of ships continues to change and evolve as do the increasing needs of the offshore operators themselves. Rigs move further and further out into deeper, more hostile waters as oil and gas exploration expands. Platforms are being sited in deeper water. Floating Production Platforms, drill ships, dive ships and pipe layers all need more powerful, more robust and more versatile support ships capable of performing different tasks as individual operations dictate - yet despite this, the UT 704 design continues to sail on, performing the work for which it was first designed. 91 vessels were built to this design in total - a testimony to the initial concept and more than just a passing nod to the creativity and forward thinking of the original design team. Rolls Royce Ulstein now build and design many of the worlds most advanced offshore shipping types - from straight supply ships to complex multi-purpose types - and shipowners continue to purchase them. However, each of these vessels owes its lineage, in no small way, to the robust UT 704 - the original workhorse of the offshore industry.

  1. Initial entry and original artwork from an unpublished article donated to SN by John Griffiths (SN member Ddraigmor) and uploaded/formatted as an SN Guide by Benjidog
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