VESSEL CONVERSION | Sanco Sailor – Research vessel rebuilt for seismic source work
Sanco Shipping's Sanco Sailor, the former PGS Apollo, entered service in February 2026 as a seismic source vessel after a six-month conversion at Vard Langsten in Norway.
The work added a DP2 system and reworked the seismic spread of a hull that PGS had commissioned in 2010 to tow ten streamers.
Sanco took over the ship on July 31, 2025, renamed it and sailed it to Vard Langsten, where it arrived in August. The seller was the Norwegian group TGS, which had previously absorbed the PGS fleet.
The conversion began with a purpose-built 3D seismic ship. Factorias Vulcano in Vigo, Spain, built the vessel to a Skipsteknisk design in 2010. PGS placed it in the medium-capacity segment, and its equipment included ten full-length streamers and twelve reels in a central arrangement, along with processing nodes, disk storage and tape drives for full onboard data processing.
Structural modifications and installation of an improved DP2 system
A low-resistance hull and an 18-knot transit speed were intended to cut steaming time between projects. Skipsteknisk said the original ship was 102 metres (335 feet) in length, with 19.2 metres (63 feet) in moulded beam and eight metres (26 feet) depth to main deck, with accommodation for 60 people plus a hospital.
Vard said the work involved substantial changes to the vessel's structure and improvements to the existing seismic equipment, together with installation of a DP2 system to enhance operational capability.
The resulting Sanco Sailor is flagged in the Bahamas with Nassau as port of registry. Principal dimensions are 106.8 metres (350.4 feet) length overall, 92.1 metres (302 feet) between perpendiculars, a 19.2-metre beam at the waterline, 22.2 metres (72.8 feet) maximum beam and 6.5 metres (21 feet) maximum draught.
Class notation is I +HULL +MACH, HABITABILITY, COMF-VIB 2, +AUT-UMS, SYS-NEQ, MON-SHAFT, HEL, INWATERSURVEY, MANOVR, + DYNAPOS AM/AT R, AVM-DPS (RP), SPS IMO A.534(13). Navigation is unrestricted.
The DP system itself is a Kongsberg KPOS DP2, paired with Kongsberg track steering running dedicated software for line-keeping during acquisition. Electrical distribution is at 690V, 440V and 230V, all at 60 Hz, and emergency and auxiliary generation comprises one 250kW unit and one 1,190kW unit.
The propulsion plant is the original diesel-mechanical arrangement. Four MAN 32/40 engines, two of 4,500 kW (6,000 hp) and two of 3,000 kW (4,000 hp), drive two controllable-pitch propellers through two Flender twin-in, single-out gearboxes, giving 7,500 kW (10,000 hp) per shaft and 15,000 kW (20,000 hp) in total.
Station-keeping and manoeuvring rely on three thrusters: a retractable, fixed-rpm, controllable-pitch bow unit of 1,500 kW, a Rolls-Royce (now Kongsberg) tunnel bow thruster of 1,250 kW and a Rolls-Royce tunnel stern thruster of 750 kW. The specification gives a bollard pull of 216 tonnes.
Maximum speed is approximately 18 knots at 65 cubic metres (15,000 gallons) of fuel a day, service speed is 12 to 14 knots at 30 cubic metres (6,600 gallons) a day and economic speed is 10 knots at 23 cubic metres (5,100 gallons) a day. Seismic shooting is 4.5 knots and 20 cubic metres (4,400 gallons) a day, a figure that includes the load from the compressor plant.
MGO capacity is 1,840 cubic metres (405,000 gallons) at 90 per cent filling, with 80 cubic metres (18,000 gallons) of lubricating oil, 174 cubic metres (38,300 gallons) of freshwater and 1,105 cubic metres (243,100 gallons) of ballast. Two Alfa Laval freshwater generators produce 30 cubic metres a day each, and an Optimarin ballast water treatment system is rated at 167 cubic metres (36,700 gallons) an hour.
Full equipment fit enabling different source modes
The source spread defines the vessel's new role. It comprises Bolt 1900 LLXT air guns arranged in six sub-arrays, each with six gun positions in use and a maximum of seven, at 2.5-metre (8.2-foot) spacing. The spread can be flown as a single, dual or triple source. In dual-source mode, three sub-arrays are assigned to each source for a maximum tow width of 200 metres (660 feet). Each gun plate carries two near-field hydrophones, one pressure transducer and one depth transducer.
Compressed air comes from five compressors: three LMF 48/138-207 E60 units of 1,800 cubic feet per minute (cfm) each and two Neumann and Esser SAPS 62 units of 2,200 cfm each, for 9,800 cfm in total at a working pressure of 2,000 psi. All run on frequency drives with automatic rpm control. An Evotec high-flow air manifold with non-return valves was installed in 2026. Firing control is Gunlink 4000 and quality control runs on RadExPro.
The tow system uses Baro Flex 18-foot floats with deflectors, the deflectors are Baro C 680-4000 and Baro DT500-2000, and door steering is handled by Ulmatec's Mini Defcon system. Umbilical cables run to 800 metres (2,600 feet).
Deck machinery on the gun and streamer decks comprises ten seismic gun winches of 950 metres (3,100 feet) each, two seismic cable winches of 12,000 metres (39,000 feet) each and 18 auxiliary winches, served by two hydraulic power packs at 280 bar. Two deck cranes are rated at 12 tonnes at 17 metres (56 feet) outreach. The retention of two long cable winches means the vessel keeps some streamer-handling capacity despite its designation as a source ship.
Positioning of the source is handled by a Fugro suite. Primary navigation is Fugro Starfix XP3/G4+, with Fugro StarPack 2 and Starfix X5 receivers. The gun array tracking uses Fugro StarTrack 2 relative GNSS, two units per sub-array. Post-processing is FGPS SeisPos and the online navigation system is ION Gator II.
Two 350mm bottom valves are fitted for acoustic transducers. Survey heading comes from a Kongsberg MGC R3 gyro compass, separate from the two Kongsberg MGC R2 units serving the bridge, and two Nortek VMCP acoustic current profilers are installed. A Simrad EA600 echosounder operates at 18, 38 and 200 kHz alongside the JRC JFE 380 bridge sounder.
Comprehensive electronics selection
Radars are Raytheon Anschütz Synapsis NB45-014 units in X-band and S-band, the autopilot is an MT Bridge Mate Navitron NT999G integrated with K-Pos, electronic charts run on MT Bridge Mate ECDIS, the speed log is a Skipper DL 850 Doppler and the voyage data recorder is a Danelec DM100. Communications include a Marlink Ku-band VSAT with Starlink, a Cobham TT-3672A FleetBroadband terminal, two JRC JUE-85 Inmarsat C terminals, a Sailor 6301 MF/HF set at 150 W, four fixed and three handheld JRC VHF radios, and five fixed and eight portable Motorola UHF units. Internal telephony is via Innovaphone IP system.
Extensive safety systems coupled with ample accommodation
Accommodation matches the original 60-person design. There are 36 single cabins and 12 two-berth cabins, all with bathrooms, plus a hospital with bathroom. Lifesaving capacity is 60 persons, provided by two 60-person lifeboats and six 20-person inflatable rafts, with 65 survival suits, 15 lifebuoys, three JRC JHS-7 emergency radios and three Jotron Tron SART 20 transponders.
The rescue craft is a Mare Safety FRB-700 unit for ten people, launched from a Vestdavit davit with a 12-tonne safe working load. Safety manning is ten persons. The mess seats 36 and the vessel has two day rooms, a conference room and a gymnasium, with air conditioning from Teknotherm Marine and Aeron.
Specialist spaces include an air-conditioned instrument room, an air-conditioned gun shack, two air-conditioned workshops and three seismic stores. The helideck is rated for a Sikorsky S-92 in daylight, with a D-value of two metres and a 14.6-tonne limit.
Fire protection comprises Autronica detection, two Itur fire pumps of 132 cubic metres per hour each and a Heien Larssen CO2 system. Waste handling uses a Gertsen and Olufsen BR-011100 BVG sewage plant, a Delitek DT-500 MC compactor and a Team Tec GS 500 CS incinerator.
