With the focus of attention in the offshore wind and offshore oil and gas industries firmly on reducing costs, interest in solutions such as offshore access systems and walk-to-work vessels that enable platforms and turbines to be accessed quickly, easily and cost-effectively is growing. That walk-to-work is one of the very few growth markets in the industry at the moment is evidenced by the growing number of vessel owners entering it and being awarded contracts. New access systems intended for both markets – such as Van Aalst’s Safeway – are also being brought to market, as are ‘service operation vessel’ or SOV concepts.
A sign of its growing importance in the market is also evidenced by DNV GL’s publication in June 2015 of an industry guidance document for walk-to-work. The guidance is the culmination of a joint industry project led by DNV GL to help those involved in developing walk-to-work solutions and enhance understanding and selection and implementation of walk-to-work solutions. Hamish Holt, a senior principal consultant with DNV GL who managed the joint project, said walk-to-work “has the potential to offer significant opportunities and benefits for operators of new or existing offshore facilities but, in order to maximise these, there are many aspects that need to be understood and considered. The comprehensive and detailed industry guidance takes a lifecycle approach to walk-to-work, from initial business need definition, through concept development to operation. It identifies and details the key aspects to help ensure that appropriate decisions are taken along the process.”
The offshore renewables workgroup at the International Marine Contractors Association (IMCA) is one of the association’s best-attended workgroups, primarily as a result of the growing number of highly relevant guidance documents for the renewables industry that it is publishing. Among the topics that IMCA is addressing that are of direct relevance to the offshore wind industry are workboat operations by crew transfer vessels. The association recently published Guidance on competence assurance and assessment: marine roles for small workboats (IMCA C 017), together with the Workboat crew logbook. Work in the pipeline includes a technical industry study on standardised boat landings, which will be published later this year. There are design differences between boat landings that vary from location to location and workboat operators are having to modify fender arrangements to take account of different boat landing designs. IMCA and the workgroup participants have been attempting to develop a consensus on the optimum design and configuration of boat landings for accessing wind turbine foundations from crew transfer vessels, to standardise the structural design and strength with the aim of reducing operator costs and increase safety of personnel when transferring to these offshore structures. Other work being undertaken with the offshore renewables industry in mind includes the revision of IMCA M 202 Guidance on the transfer of personnel to and from offshore vessels and, in particular, the vessel-to-vessel supplement.
Safeway/Van Aalst spokesperson Remko de Boer highlighted the purpose-designed walk-to-work vessel that NAM recently chartered from Royal Wagenborg as a prime example of this trend, but others have been delivered recently, are on order and are being designed. “In the current market, many vessel owners are looking at alternative strategies for employment for their assets, and adding accommodation and an access system opens up a whole new market segment for them,” said Mr de Boer. However, says Mr de Boer, the availability of high quality vessels is only half the equation and will not induce operators towards the use of walk-to-work concepts on their own. The key issue, he believes, is ‘workability’ and the level of availability that the combination of vessel and walk-to-work access systems can provide.
“The average gangway system available on the market has a workability limit of around 2.5m significant wave height,” he said. “This is achieved on main deck level but will often reduce when installed on higher decks. A 2.5m wave height limit offers operators a year-round workability of around 75 per cent. This of course depends on the exact location and the motion behaviour of the vessel used but effectively means full workability during the summer season and slightly better than 50 per cent in the remainder of the year. Operators could find they have a walk-to-work system that provides the availability they need in the summer, but they may have to return to their traditional way of working in wintertime and pay a premium for doing so.” In his view, the situation would be much different – and the attractiveness of a walk-to-work solution much greater – if a vessel/access system could guarantee workability in up to 3.5m significant wave height. “In that case, year-round workability improves to 92 per cent,” which, he says, provides operators with a much sounder basis for moving to a walk-to-work solution.
Another well known player in the walk-to-work access system market, Osbit Power in the UK, continues to develop its range of access systems. The company’s access solutions, based on its MaXccess offshore access systems, are designed around the principle that passive compensation of vessel motions provides a more reliable, safer and cost-effective access solution than actively compensating motions. The company’s managing director, Ben Webster, said Osbit Power can provide three main types of access solution, ranging from large, passive telescopic gangways to active systems for monohulls for the offshore oil and gas and offshore wind industries to smaller systems primarily intended for crew transfer vessels for the offshore wind industry. Interest in the latter is growing internationally, including in Japan for the planned Fukushima offshore windfarm. Mr Webster said Osbit Power is engaged in ongoing discussions with clients in the offshore oil and gas sector regarding larger systems, such as the one it supplied to Subsea 7 last year, “looking to adapt to the needs of the market” as a whole, whether this be for fixed systems installed on a vessel or systems installed on a rental basis. Mr Webster also highlighted the ability of Osbit Power’s access systems to be used to transfer cargo from a vessel to an offshore installation, complementing the ability of cranes on vessels to do so.