Trans RINA, Vol 153, Part A1, Intl J Maritime Eng, Jan-Mar 2011
platforms or rigs, located adjacent to both fixed structures, platforms and floating units such as FPSOs, semi-submersible drill ships, jack-ups, spar platforms, etc. A means of holding position is necessary and this could be achieved by the use of a mooring/anchor system or a dynamic positioning system. Transfer of personnel between the flotel and the offshore platform is normally provided by a telescopic gangway.
of introduction, Table 2 shows in a synthetic way the four main floating types of structures used as flotels.
As mentioned, flotels are positioned alongside the host installation and connected to it by means of a telescopic gangway. This also provides the rig with a “safe haven” in the event of an emergency. Together with the supply of various utilities to the installation to which it is connected, the floatels
provide excellent welfare
services, catering and comfortable accommodation for the offshore workforce.
3.2 TYPES AND BRIEF HISTORY Figure 6: semisubmersible flotels attached to oil rigs.
JCE Group AB (founder of Consafe Offshore AB) built the world’s first purpose built flotel semi-submersible in 1977, named Safe Astoria. Since that time, the best solution for short-term offshore accommodation consists of the use of these flotels next to the rig. But these semi- submersible flotels also present some disadvantages:
Figure 7: telescopic gangway in a semisubmersible flotel. (source: Prosafe AS).
The need for offshore flotels comes from the fact that oil platforms (FPSOs, drilling rigs,…) are designed to accommodate only those required for normal operation, which means between 100 and 200 people: For example, the FPSO “Texaco Captain” has a capacity of 200 people; the drilling rig “Stena Clyde" only 160 people. The problem comes when extra capacity is needed to accommodate workers during operations such as:
construction and installation. maintenance / shutdowns / refurbishment projects. decommissioning. hook-up of satellite fields to existing infrastructure.
Not only do such operations require more
accommodation, but there are other needs such as storage areas and repair workshops, lifting capacity, and diving.
The options for fulfilling these requirements of extra accommodation and services are varied, and the most appropriate will depend on the mix of services required. Table 1 shows in a schematic way those options with gross day rates and weather operational environments. Among these options, a flotel is best when the only requirement is for extra
accommodation: whether
accommodation is needed for 2 months or 3 years, it can be made ready within a few days. And some of them offer also extra duties, like small cranes or ROVs, but with a capacity much lower than a
real offshore
construction vessel. The following paragraphs study in detail each of the structures used as a flotel, but by way
High cost of acquisition. High operation costs. Limited mobility. Lack of multipurpose operation. Complex connection systems. Highly variable operation frequency depending on adverse weather.
In 2005, M/V Edda Fjord, a platform supply vessel of Østensjø
Group, was converted to provide
accommodation services offshore Nigeria for a total of 330 people. Therefore, it is considered the first flotel ship. It supported the Bonga FPSO during the onsite construction, hook-up and commissioning of the FPSO facility. Edda Fjord was connected to the FPSO by means of a gangway and took advantage of the dynamic positioning system onboard to maintain a precise and continuous position. The living quarters were containerized accommodation modules, as shown in the picture below:
Figure 8: M/V Edda Fjord in operation as flotel and a virtual image with container module. (source: Østensjø Group and SKM Offshore)
In the following years, and as a consequence of the excellent performance of Edda Fjord, several companies decided to build their own flotel ships (Table 3 shows the current fleet, in operation and on order).
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©2011: The Royal Institution of Naval Architects
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