Iolair (Gaelic
Scottish Gaelic language
Scottish Gaelic is a Celtic language native to Scotland. A member of the Goidelic branch of the Celtic languages, Scottish Gaelic, like Modern Irish and Manx, developed out of Middle Irish, and thus descends ultimately from Primitive Irish....

 for eagle) is a specialised semi-submersible
A semi-submersible is a specialised marine vessel with good stability and seakeeping characteristics. The semi-submersible vessel design is commonly used in a number of specific offshore roles such as for offshore drilling rigs, safety vessels, oil production platforms and heavy lift cranes.The...

 offshore platform designed for BP
BP p.l.c. is a global oil and gas company headquartered in London, United Kingdom. It is the third-largest energy company and fourth-largest company in the world measured by revenues and one of the six oil and gas "supermajors"...

 to support and service oil platform
Oil platform
An oil platform, also referred to as an offshore platform or, somewhat incorrectly, oil rig, is a lаrge structure with facilities to drill wells, to extract and process oil and natural gas, and to temporarily store product until it can be brought to shore for refining and marketing...

s in the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

 and served as an emergency support vessel (ESV) in the Forties Oil Field. Since 2000 she has been working in the Bay of Campeche
Bay of Campeche
The Bay of Campeche is the southern bight of the Gulf of Mexico. It is surrounded on three sides by the Mexican states of Campeche, Tabasco and Veracruz. It was named by Francisco Hernández de Córdoba and Antonio de Alaminos during their expedition in 1517...

, Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 as an offshore construction and service vessel.


Iolair is a self-propelled, twin hull, vessel and operates as a dynamically positioned
Dynamic positioning
Dynamic positioning is a computer controlled system to automatically maintain a vessel's position and heading by using its own propellers and thrusters...

 (DP) construction support vessel. The vessel can operate up to a water depth of 488 metres (1,601 ft), is 102 metres (334.6 ft) long and 51 metres (167.3 ft) wide, and has 207 beds with single and double occupancy.

This unique vessel did not start as an ESV, but rather as the concept of a maintenance and support vessel (MSV). It was proposed for the Forties oil field, operated by BP Petroleum Development Company Ltd in the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

. A particular feature of the design by the Naval Architects was that there was no cross-bracing between the pontoons
Pontoon (boat)
A pontoon is a flotation device with buoyancy sufficient to float itself as well as a heavy load. A pontoon boat is a flattish boat that relies on pontoons to float. Pontoons may be used on boats, rafts, barges, docks, floatplanes or seaplanes. Pontoons may support a platform, creating a raft. A...

. Instead, the platform was given extra strength by a box-girder construction and diagonal bracing was arranged from the centre of the platform to the pontoons. This arrangement remained virtually unchanged to the build completion and offered exceptional speed when the vessel was de-ballasted on the surface. The intention was to achieve a rapid response to emergencies, wherever they might be experienced in the North Sea.

As an MSV, the vessel was always conceived to provide accommodation for about 220 persons, saturation diving
Saturation diving
Saturation diving is a diving technique that allows divers to reduce the risk of decompression sickness when they work at great depth for long periods of time....

 facilities, a large workshop, craneage, and helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...

 landing area with hangar and re-fueling. All were still featured in the eventual design but had been enhanced with other features and sophistication much of which was to support the emergency role. ESV incorporated novelty and ideas that were years ahead of their time. Indeed, part of the brief was that she should still be modern ten years after entering service.

The saturation diving system was equipped with an advanced launch and recovery system.


She was built by Scott Lithgows in Port Glasgow
Port Glasgow
Port Glasgow is the second largest town in the Inverclyde council area of Scotland. The population according to the 1991 census for Port Glasgow was 19426 persons and in the 2001 census was 16617 persons...

, and launched on 6 April 1981. In her early years, she was based in the BP Forties Oil Field.

In 1995, she was sold to U.S.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 drilling company Reading & Bates. She was to be converted to a workover/well intervention vessel and was stationed West of Shetland. The modifications included removal of some of the top structures, removal of the fire-fighting systems, closing of the dive tube and wave surge tank
Surge tank
A surge tank is a standpipe or storage reservoir at the downstream end of a closed aqueduct or feeder pipe to absorb sudden rises of pressure as well as to quickly provide extra water during a brief drop in pressure...

. However the intended conversion was never carried out and she was heavily involved in the installation of subsea production equipment using Remote Operated Vehicles. She was also heavily involved in the commissioning of the Foinaven
Foinaven oilfield
Foinaven oil field is deepwater oil development approximately west of the Shetland Islands. Together with Schiehallion, Loyal and Clair fields it forms the area generally termed as the West of Shetland.-Field description:...

 and Schiehallion
Schiehallion oilfield
The Schiehallion oilfield is a deepwater offshore oilfield approximately west of the Shetland Islands in the North Atlantic Ocean. The Schiehallion and adjacent Loyal field were jointly developed by BP on behalf of the Schiehallion field partners; BP, Shell, Amerada Hess, Murphy Oil, Statoil and...

 floating production vessels.

In 2000 she left the UK oilfields and went to the Bay of Campeche, Mexico, working in the Cantarell Field
Cantarell Field
Cantarell Field or Cantarell Complex is an aging supergiant oil field in Mexico. It was discovered in 1976 by a fisherman, Rudesindo Cantarell. It was placed on nitrogen injection in 2000, and production peaked at in 2003. In terms of cumulative production to date, it is by far the largest oil...

. There she carries out construction and platform support work. She was sold in 2001 by Transocean
Transocean Ltd. is one of the world's largest offshore drilling contractors. The company rents floating mobile drill rigs, along with the equipment and personnel for operations, to oil and gas companies at an average daily rate of US$282,700...

, who had taken over Reading and Bates, and is now owned by Exeter Marine Ltd. and registered in the Marshall Islands
Marshall Islands
The Republic of the Marshall Islands , , is a Micronesian nation of atolls and islands in the middle of the Pacific Ocean, just west of the International Date Line and just north of the Equator. As of July 2011 the population was 67,182...

, a long way from her original registered port of Dundee
Dundee is the fourth-largest city in Scotland and the 39th most populous settlement in the United Kingdom. It lies within the eastern central Lowlands on the north bank of the Firth of Tay, which feeds into the North Sea...

 in Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...


Industry firsts

  • Heave/swell compensation in the diving tube to enable operation in rougher weather.
  • A Citadel area to which people could retire and survive if the vessel was engulfed in gas.
  • A drenching system to cool exterior surfaces if the vessel was close to a burning platform.
  • The largest capacity and longest range firefighting monitors ever at sea.
  • Fixed water-cannon on the after columns to cool the underside of production platforms.

Iolair is assured of its place in history by being the subject of a 28p
A penny is a coin or a type of currency used in several English-speaking countries. It is often the smallest denomination within a currency system.-Etymology:...

 commemorative stamp issued by Post Office Ltd.
Post Office Ltd.
Post Office Ltd is a retail post office company in the United Kingdom that provides a wide range of products including postage stamps and banking to the public through its nationwide network of post office branches.-Structure:Post Office Ltd...

on 25 May 1983. This was one of a series of three stamps celebrating British Engineering Achievements.
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