In this second of our four sector-specific guides to the world's LNG-fuelled tonnage, Mike Corkhill reports on growth in bookings for PSVs
There has been little change in the number of service and supply vessels in the world LNG-fuelled fleet over the past year. According to LNG World Shipping’s new review of gas-powered ships that are not LNG carriers, both the operational and on-order fleets of service and supply vessels rose by three units.
Platform supply vessels (PSVs) figure prominently in the at-sea LNG-powered service and supply fleet, accounting for 20 of the 33-ship complement. The orderbook, in contrast, shows much more variety, with a portfolio encompassing dredgers, a jack-up rig, a semi-submersible crane vessel, a cable-layer and a wind farm installation ship.
DEME of Belgium has been a leading advocate of LNG-fuelled dredgers and has investigated the challenges of using gas to power them. Factors to be weighed up include bunker tank size and location, LNG bunker availability, shipboard bunkering connections, crew training and the step load capability of the various gas-burning engine options.
Combined with its cold box encasement a cylindrical Type C LNG bunker tank occupies about three times as much space as a prism-shaped tank of marine gas oil (MGO) containing the same energy.
While Type C pressure vessel tanks offer many advantages, accommodating them has a significant impact on vessel layout. Also, the tank location restrictions imposed by the new International Code of Safety for Ships using Gases or other Low-Flashpoint Fuels (IGF Code) add another level of complexity to the design challenge.
Naval architects working on the DEME dredgers found that dual-fuel diesel engines worked best for the vessels as they have a better step load capability than gas engines. The mix of LNG and MGO bunker tank capacities associated with such propulsion units also offers a measure of redundancy.
The aim is to optimise the use of LNG, assuming that the cost of this fuel is lower than MGO, but to provide sufficient MGO as a backup. The crew can switch to MGO if the dredger has to operate longer than planned before the next LNG bunkering stop.
Harbour tugs are the second most popular type of LNG-fuelled service and supply vessel, after PSVs. There are now six gas-powered tugs in service and eight on order. Wärtsilä, with its medium-speed dual-fuel engines, and Rolls-Royce, with its gas-only units, have both enjoyed success in providing tug propulsion systems.
LNG-fuelled tugs are in operation in Norway, China and Japan, while Dubai and Singapore are poised to join the club as a result of vessels on order. The next new member could well be the US where a number of designs for gas-fuelled tugs and towboats have been tabled.
Three of the tugs on order are under construction at the Gondan yard in Spain for Østensjø Rederi AS. The owner has opted for Wärtsilä engines and the series is slated to provide ship assist and escort services for the LNG carriers loading cargoes at the Statoil export terminal near Hammerfest in northern Norway.
LNG-fuelled service and supply ships, March 2017
|STATUS||SHIP NAME||SHIP TYPE||DELIVERY DATE||OWNER||SHIPBUILDER||ENGINE||PROPULSION||CLASS SOCIETY|
|1||In service||Stil Pioneer||PSV||2003||Møkster||Kleven Ulsteinvik||Wärtsilä||DF||DNV GL|
|2||Viking Energy||PSV||2003||Eidesvik||Kleven Ulsteinvik||Wärtsilä||DF||DNV GL|
|3||Viking Queen||PSV||2008||Eidesvik||West Contractors||Wärtsilä||DF||DNV GL|
|4||Viking Lady||PSV||2009||Eidesvik||West Contractors||Wärtsilä||DF||DNV GL|
|5||Barentshav||Patrol vessel||2009||Remøy||Myklebust||Mitsubishi||Gas + oil||DNV GL|
|6||Bergen||Patrol vessel||2010||Remøy||Myklebust||Mitsubishi||Gas + oil||DNV GL|
|7||Sortland||Patrol vessel||2010||Remøy||Myklebust||Mitsubishi||Gas + oil||DNV GL|
|8||Skandi Gamma||PSV||2011||DOF||STX OSV Soviknes||Wärtsilä||DF||DNV GL|
|9||Normand Arctic||PSV||2011||Solstad||STX OSV Langen||Wärtsilä||DF||DNV GL|
|10||Viking Prince||PSV||2012||Eidesvik||Kleven Ulsteinvik||Wärtsilä||DF||DNV GL|
|11||Viking Princess||PSV||2012||Eidesvik||Kleven Ulsteinvik||Wärtsilä||DF||DNV GL|
|12||Island Crusader||PSV||2012||Solstad||STX OSV Brevik||Rolls-Royce||Gas||DNV GL|
|13||Island Contender||PSV||2012||Solstad||STX OSV Brevik||Rolls-Royce||Gas||DNV GL|
|14||Olympic Energy||PSV||2012||Solstad||STX OSV Aukra||Wärtsilä||DF||DNV GL|
|15||Rem Leader||PSV||2013||Remøy Shipping||Kleven Verft||Wärtsilä||DF||DNV GL|
|16||Econuri||Harbour vessel||2013||Incheon Port Authority||Samsung||Wärtsilä||DF||KR|
|17||Hai Yang Shi You 521||Tug||2013||CNOOC||Guangzhou Huangpu||Wärtsilä||DF||CCS|
|18||Hai Yang Shi You 522||Tug||2013||CNOOC||Guangzhou Huangpu||Wärtsilä||DF||CCS|
|19||Børgoy||Tug||2014||Buksér og Berging||Sanmar||Rolls-Royce||Gas||DNV GL|
|20||Bokn||Tug||2014||Buksér og Berging||Sanmar||Rolls-Royce||Gas||DNV GL|
|21||Turva||Patrol vessel||2014||Finnish Border Guard||STX Turku||Wärtsilä||DF||DNV GL|
|22||Stril Barents||PSV||2015||Møkster||Hellesøy||Wärtsilä||DF||DNV GL|
|23||Harvey Energy||PSV||2015||Harvey Gulf||Trinity Offshore||Wärtsilä||DF||ABS|
|24||Harvey Power||PSV||2015||Harvey Gulf||Trinity Offshore||Wärtsilä||DF||ABS|
|25||Harvey Liberty||PSV||2016||Harvey Gulf||Trinity Offshore||Wärtsilä||DF||ABS|
|26||Harvey Freedom||PSV||2017||Harvey Gulf||Trinity Offshore||Wärtsilä||DF||ABS|
|27||Rem Eir||PSV||2015||Remøy Shipping||Kleven Verft||Wärtsilä||DF||DNV GL|
|28||Hai Yang Shi You 525||Tug||2015||CNOOC||Zhenjiang||Rolls-Royce||Gas||CCS|
|29||Siem Symphony||PSV||2015||Siem Offshore||Hellesøy||Wärtsilä||DF||DNV GL|
|30||Siem Pride||PSV||2015||Siem Offshore||Remontowa||Wärtsilä||DF||DNV GL|
|31||Sakigaki||Tug||2015||NYK Line||Keihin Dock||Niigata||DF||ClassNK|
|33||Siem Thiima||PSV||2017||Siem Offshore||Remontowa||Wärtsilä||DF||DNV GL|
|1||On order||Elemarateyah||Tug||2017||Dubai Maritime City||DDW Dubai||Wärtsilä||DF||Tasneef|
|3||Siem Melody||PSV||2017||Siem Offshore||Remontowa||Wärtsilä||DF||DNV GL|
|4||Siem Rhapsody||PSV||2017||Siem Offshore||Remontowa||Wärtsilä||DF||DNV GL|
|5||Harvey America||PSV||2017||Harvey Gulf||Trinity Offshore||Wärtsilä||DF||ABS|
|6||Harvey Patriot||PSV||2017||Harvey Gulf||Trinity Offshore||Wärtsilä||DF||ABS|
|7||Hammerfest||Tug||2017||Østensjø Rederi||Astilleros Gondan||Wärtsilä||DF||BV|
|8||unnamed||Tug||2017||Østensjø Rederi||Astilleros Gondan||Wärtsilä||DF||BV|
|9||unnamed||Tug||2017||Østensjø Rederi||Astilleros Gondan||Wärtsilä||DF||BV|
|10||Scheldt River||Dredger||2017||DEME||Royal IHC||Wärtsilä||DF||BV|
|11||Minerva||Dredger||2017||DEME||Royal IHC||Anglo Belgian||DF||BV|
|12||Bonny River||Dredger||2017||DEME||Cosco Guangdong||Wärtsilä||DF||unnamed|
|16||Sleipnir||Semisub crane vessel||2018||Heerema||Sembawang||unnamed||DF||unnamed|
|17||Werkendam||Dredger||2018||Van Oord||Neptune Shipyards||unnamed||DF||unnamed|
|18||Ecodelta||Dredger||2018||Van der Kamp||Barkmeijer||Anglo Belgian||DF||unnamed|
|19||Atair||Survey ship||2018||German Maritime Authority||Fassmer||unnamed||unnamed||unnamed|
|20||unnamed||Tug||2018||Ningbo Port Co||unnamed||Niigata||DF||CCS|
|21||unnamed||Tug||2018||Keppel Smit Towage||Keppel||unnamed||unnamed||unnamed|
|23||Orion||Wind farm installation vessel||2019||GeoSea||Cosco||unnamed||unnamed||unnamed|
Source: LNG World Shipping, March 2017
* conversion project
DF: medium-speed dual-fuel
HPLSDF: high-pressure, low-speed dua-fuel
LPLSDF: low-pressure, low-speed dual fuel