The standby and emergency response vessel has evolved from modified trawler to bespoke rescue craft. Here, we trace the development of one of the most stalwart vessels in the offshore fleet
Standby search and rescue vessels (SSRVs), or emergency response and rescue vessels (ERRVs), have increased significantly in size and complexity over the last 30 years, evolving into what could be considered the offshore oil and gas market’s equivalent of a Swiss Army knife.
Beyond their primary role of offshore personnel safety, SRRVs also carry out oil spill recovery, rescue towing and dynamic positioning (DP) duties. Highlighting their development, OSD-IMT naval architect Duncan Grigg explains: “The typical ERRV of the pre-Piper Alpha period was a converted trawler with a couple of fast rescue craft, rudimentary survivor facilities and limited manoeuvrability, courtesy of a single engine and propeller and a small bow thruster.”
Sentinel Marine chief executive Rory Deans agrees: “I first came into this market 35 years ago, so things have changed dramatically. We’ve gone through many stages; they were first fishing vessels, which were later upgraded to hospitals, then small platform supply vessels. Now they are purpose-built, multi-function vessels, so they are much more marketable.”
Last year, Aberdeen-based OSV operator Sentinel Marine announced it was investing £36M (US$46M) in three newbuild multirole ERRVs.
Designed by Singapore-based Khiam Chuan Marine (KCM), Cromarty Sentinel, Trafalgar Sentinel and Viking Sentinel will be built by China's Fujian Southeast Shipyard and delivered by the end of 2020.
The trio of OSVs will be an enhanced version of the KCM-designed ERRVs that Sentinel Marine has been operating in the North Sea over the past four years. They will all feature increased DP capabilities with a notation of DP2, a firefighting class of 1, oil recovery, liquid mud and dry bulk capacities.
Their primary role will be ensuring offshore personnel safety, but they will also be able to carry out oil recovery, rescue towing and DP duties.
“While conversions (more recently of OSVs) continue to account for a reasonable part of the ERRV market,” Mr Grigg says “newbuilds are now more common, particularly as many older vessels have been removed from the market by scrapping in recent years.”
Dozens of ERRVs have been built to Dutch ship design and marine consultancy OSD-IMT designs. “There is variation in the design of modern ERRVs, driven either by specific contract requirements from field operators, or what owners perceive will be future demand,” explains Mr Grigg.
He continues: “At the most basic is the ‘pure’ ERRV. Such a vessel is intended for instances where only a safety standby capability is required, and the main design driver is the reduction of the day rate. This is obtained by making the vessel relatively small (45 m to 50 m in length overall is common) and adopting a simple machinery arrangement. A single main engine and propeller, with a retractable azimuth thruster forward is one such arrangement, and in standby mode the vessel can operate on the retractable thruster for economical operation.”
Mr Grigg notes that increasingly, additional operations are required: “A common ‘extra’ is to have a vessel capable of limited platform supply capability, with such vessels termed ‘field support vessels’. Usually such vessels are in the region of 55 m to 65 m length overall and would tend to have a diesel electric machinery arrangement more typical for a platform supply vessel.”
For fields with FPSOs and offloading buoys a combined ERRV/tanker support vessel is sometimes specified, which is a combination of large ASD tug of approximately 100 tonnes bollard pull and ERRV. “In a similar vein, large PSVs and AHTS are sometimes outfitted as ERRVs whilst maintaining their role as PSV or AHTS. The combination of roles on a single ship will be driven by the requirements and economics of the specific field at which the ERRV operates,” Mr Grigg explains.
North Star Shipping’s Grampian Endurance is an IMT960 tanker assist class OSV
Evolution of the SSRV
Mr Grigg laid out the history of the SSRV. The date 6 July 1988 is etched into the collective memory of those involved in offshore oil and gas. It is the date when a gas condensate explosion on the Piper Alpha platform led to the deaths of 167 people in the resulting explosions and fire. The large firefighting, hospital and accommodation vessel Tharos, which was in the vicinity at the time of the disaster, proved to be largely ineffectual as the disaster unfolded, and the majority of survivors (37 out of 59) were recovered by the SSRV Silver Pit.
Silver Pit was typical of contemporary SSRVs. A converted sidewinder trawler originally built in Canada in 1947, it featured a single engine and propeller, a small bow thruster and hand steering. A small fast rescue craft and davit was fitted amidships and the former fish room was converted to survivor accommodation, with seating and rudimentary medical facilities. The provision of SSRVs was mandated in the UK Sector by the Mineral Workings Act, introduced in the aftermath of the Sea Gem disaster of 1965, and the requirements for vessels and crew bordered on Laissez-Faire.
The 1991 Cullen report into the Piper Alpha disaster, while praising the actions of the master and crew, was critical of the Silver Pit, citing its lack of manoeuvrability and shortcomings in arrangements for transfer of survivors, as well as reliability issues associated with the age of the vessel. Around this time, operators of safety standby vessels (SSV) started buying older stern trawlers, anchor handling tugs and platform supply vessels for conversion, but some owners came to the conclusion that it would be possible to have something rather better by building purpose-built vessels.
Starting from Scratch
At the time, Neil Patterson had recently founded Marine Design Service, which later became IMT Marine Consultants, now called OSD-IMT, and was working out of the spare room of his Carnoustie home.
“I was working on three projects at the time,” says Mr Patterson, “so I had a drawing board in the spare room, one in the garage, one in the shed and my computer in a cupboard under the stairs.
“I was doing some consultancy work for an offshore contracting and consultancy company who had been approached by a shipowner who was also an existing client with an enquiry to design a newbuild SSV. One day I asked how they were getting on and was advised that nothing had been progressed with the other company. As I was working on some conversions and modifications, converting existing old trawlers and offshore vessels into SSV, I had some ideas for a newbuild vessel, so they gave me the go ahead to start developing a design.”
At the time there were no applicable regulations in force to govern the design of SSVs, so, armed with the conclusions of the Cullen Report, Mr Patterson and his small team began working out a design. At that stage the design featured a single azimuth thruster aft and a pump-jet thruster forward. In the end the owner decided to purchase and convert two newbuild stern trawlers which were in an advanced state of construction, rather than develop a purpose-built vessel design, but fortunately there were others in the market for such a vessel.
Through contacts in the industry, IMT was able to secure a contract with Sunset Shipping in the Isle of Man for the design and supervision of two newbuild SSRVs, to be constructed at Yorkshire Drydock in Hull. During the tender process, the design was further developed and changed to the final arrangement, with two azimuth thrusters aft and a forward retractable azimuth to give improved redundancy.
“They are good sea-keeping vessels, very comfortable in heavy weather and the crews like them”
Viewed today, the site of the now long-closed Yorkshire Drydock shipyard (YDD) seems an unlikely place to build a ship. Squeezed between Lime Street and the narrow River Hull into which new vessels were launched, archaic construction practices and small lifting capacities meant that vessels were erected piecemeal. However, the yard had a well-established track record in the construction of coasters and had recently constructed a cruise vessel for the River Nile. Therefore, it was a good choice for the construction of this small, specialised vessel.
IMT however faced other challenges.
“Our contract was for the basic design, construction drawing approval, as Owners representative and construction supervision,” continues Mr Patterson. “Although we had our own experienced construction steelwork supervisor, he was already committed on a contract to supervise a newbuild ferry and a ferry lengthening project, but as we had already worked on some projects with YDD, I knew Tony Lapthorn who had just finished building and supervising a series of coasters at the yard for his own company. As Tony was semi-retired from day-to-day ship management we managed to secure him to be our on-site superintendent, and as he knew the yard very well he was able to get the workforce he wanted working on the project.”
Yard number 332 Scott Guardian was launched in 1993 and went into long-term charter arrangement for Amerada Hess at the Scott Platform.
The second vessel in the series, Trafalgar Guardian, was completed in 1994 and was long-term chartered to Enterprise Oil for the Nelson platform. Both vessels were operated and managed by Seaboard Offshore Aberdeen on behalf of the owners Sunset Shipping Ltd.
Due to corporate mergers and takeovers the vessels have sailed for several owners and under different names. In 2005, Scott Guardian and Trafalgar Guardian sailed for Viking Offshore Services and were renamed Viking Guardian and Viking Victory, respectively. When Viking Offshore Services was sold to Vroon in 2008 the vessels were renamed VOS Guardian and VOS Victory.
VOS Guardian has just completed its 25-year special survey, so the book is not yet closed on the story of these vessels. While the conversions of the same period have mostly gone to the scrapyard, the erstwhile Scott Guardian and Trafalgar Guardian continue on. Vroon Offshore’s Robbie Coull offershis views on why they remain valuable assets: “The layout for survivor flow is probably still the most effective and they are arguably still the most manoeuvrable vessels within the industry. We have a master who is of the opinion that they are the most manoeuvrable vessels he has sailed on.”
Mr Coull continues: “They are good sea-keeping vessels and very comfortable in heavy weather. The crews that have sailed on them like them; I was fortunate to serve as master on the Scott Guardian for a number of years shortly after the vessels were built and know their capabilities. The crew accommodation is excellent, with large cabins with bunks inboard just off the centre line of ship. They have operated for the past 25 years with little or no major problems.”
Subsequently, 39 ERRVs have been built to nine different OSD-IMT designs, and most have followed the general concept introduced by Scott and Trafalgar Guardian.