The Singapore owner has taken delivery of its first dual-fuel harbour tug, PSA Aspen
Singapore’s drive to develop cleaner port operations took another important step forward with the delivery of a dual-fuel, ship-handling tug. PSA Marine began operating its first gas-fuelled tug after PSA Aspen was completed by PaxOcean Shipyard.
This harbour tug was built to a Robert Allan design with an engineroom system that runs on both gas and marine diesel.
PaxOcean built PSA Aspen to a RAmparts 2800-DF design and Bureau Veritas class as a harbour tug with high levels of automation and for coastal towage.
This 447-gt tug has an overall length of 28.2 m and moulded beam of 11.5 m. It has a hull depth of 5.5 m and maximum navigational draught of 4.6 m.
During sea trials, PSA Aspen achieved a bollard pull of more than 56 tonnes and free running speed ahead of over 13 knots.
Its main propulsion, supplied by Niigata, includes two medium-speed 6L28AHX dual-fuel main engines, each generating 1,618 kW of power at 750 rpm.
These each drive a steel shaft connected to a Niigata ZP-31 Z-Peller propulsion unit, with a 220-cm diameter fixed-pitch propeller, and zero-to-idle slipping clutch.
These engines can transition seamlessly between gas and diesel fuels and back without impacting power output. When operating in gas mode, they comply with IMO Tier III emissions requirements but attain IMO Tier II in diesel mode.
Gloryholder Liquefied Gas Machinery supplied the LNG storage tank and gas fuel system on PSA Aspen. This comprises a 25-m3 vacuum insulated IMO Type C LNG storage tank.
Robert Allan said it worked with Bureau Veritas to design, engineer and configure the gas system for PSA Aspen.
They previously worked together on a RAstar 4000-DF tug design used to construct a series of dual-fuelled escort tugs operating at the Melkoya LNG production terminal near Hammerfest, northern Norway.
“By utilising the RAstar 4000-DF reference design, the approval process [for RAmparts 2800-DF] was significantly streamlined,” said Robert Allan. “The same innovative features used on the reference tug were easily transferred and refined for the new design, providing PSA Marine with an evolutionary tug.”
Inside PSA Aspen’s engineroom is electrical plant consisting of two identical Perkins E70 TAG3M ship service generators with a power output of 130 ekW.
PaxOcean equipped this tug with deck machinery for a variety of towage and ship manoeuvring operations. This includes two stern anchor winches and a MacGregor-supplied MG-HTW1 hydraulic, double-drum hawser winch on the bow, which is spooled with two 220-m lines on each drum. Palfinger supplied a PK12000M foldable knuckle-boom deck crane for the aft deck.
PSA Aspen’s fendering includes an upper 800 x 400 mm cylindrical fender and a lower 600 x 300 mm cylindrical fender at the bow. A 300 x 300 mm hollow-D fender provides protection at the main deck sheer line and along the knuckle while at the stern there is 600 x 300 mm cylindrical fendering.
The vessel’s accommodation was outfitted to comply with the latest Maritime Labour Convention compliant standards for a crew of up to six people. All the crew cabins are outfitted with en-suite bathrooms and there is a common bathroom located close to the wheelhouse.
This is the third LNG-fuelled tug to enter service in the Port of Singapore after two were delivered to Keppel Smit Towage (KST Liberty) and Maju Maritime (Maju Loyalty) in 2018. Their introduction is in parallel to the developing LNG bunkering facilities in Singapore.
PSA Marine has another dual-fuel tug of similar design to PSA Aspen on order at PaxOcean.
PSA Aspen particulars
Owner: PSA Marine
Designer: Robert Allan
Class: Bureau Veritas
Type: dual-fuel harbour/coastal
Length, oa: 28.2 m
Beam, moulded: 11.5 m
Hull depth, moulded: 5.6 m.
Total power: 3,236 kW
Bollard pull: 56 tonnes
Main engines: 2 x Niigata 6L28AHX-DF
Propulsion: 2 x Niigata ZP-31 Z-Peller
Gensets: 2 x Perkins E70 TAG3M
Fuel oil storage: 50 m3
LNG storage: 25 m3