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RAL-designed dual-fuel tug enters service in Asia

Aug 16, 2019 03:14 PM

Courtesy Robert Allan Ltd.

(VANCOUVER, British Columbia) — PaxOcean Shipyard Pte. Ltd. has delivered the dual-fuel ship-handling tug PSA Aspen, a Robert Allan Ltd. RAmparts 2800-DF design, to PSA Marine, Singapore. PSA Aspen is the first dual-fuel tug to enter service with PSA Marine in the Port of Singapore and the first Robert Allan Ltd. designed dual-fuel tug to enter service in Asia.

The cooperation between Robert Allan Ltd. and PSA Marine began in 2002, with the design of Z-Tech tug series. Since that time the two companies have developed a close, cooperative working relationship, providing custom-tailored tugs for the international market. There are more than two dozen of Robert Allan Ltd. Z-Tech RAmparts and RAstar tugs in the PSA Marine fleet currently.

RAmparts 2800-DF is a dual-fuel variant of the popular RAmparts series and is able to operate on either natural gas or diesel fuel.

The particulars of tugboat PSA Aspen are:

Length overall: 28.2 meters
Beam, molded: 11.5 meters
Depth, molded: 5.55 m
Maximum nav: 4.61 m
Gross tonnage: 447 GRT
Fuel oil: 50 cubic meters
LNG (gross): 25 cubic meters
Potable water: 45 cubic meters

The tug was designed and constructed to the following Bureau Veritas class notation: BV ✠ 1+Hull, +MACH, TUG – DUAL FUEL, COASTAL AREA, +AUT UMS, IWS

Robert Allan Ltd. worked in cooperation with Bureau Veritas to utilize the gas system and vessel configuration design principles used on the previously completed RAstar 4000-DF tug design series. By utilizing the RAstar 4000-DF reference design the approval process was significantly streamlined, and 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.

Trial results were as follows:

Bollard pull, ahead: 56.1 mt
Free running speed, ahead: 13-plus knots

The vessel’s accommodations are outfitted to MLC compliant standards for a crew of up to six personnel. All the crew cabins are outfitted with private en-suite washrooms, with a common washroom located in near the wheelhouse.

Main propulsion for the tug comprises a pair of Niigata 6L28AHX-DF main engines, each rated at 1,618 kW at 750 rpm, driving a straight-line steel shaft system to a Niigata ZP-31 Z-Peller propulsion unit with a 2,200 mm diameter fixed pitch propeller and zero to idle slipping clutch. The Niigata main engines attain IMO Tier III emission requirements while operating in Gas Mode, and IMO Tier II emission requirements while in diesel mode.

The vacuum insulated IMO Type C LNG storage tank and fuel gas system was provided by Gloryholder Liquefied Machinery (DL) Co. Ltd. With integration of main engine and fuel gas system complete in cooperation with Niigata.

The electrical plant consists of two identical Perkins E70 TAG3M ship service generators with a power output of 130 ekW.

Ship handling fenders at the bow consists of an upper 800 x 400 mm cylindrical fender with a lower 600 x 300 mm cylindrical fender. A 300 x 300 hollow “D” fender provides protection at the main deck sheer line and along the knuckle, and 600 x 300 mm cylindrical fender is used at the stern.

The deck machinery comprises a MacGregor MG-HTW1 hydraulic double drum hawser winch on the bow, spooled with 2 x 220 m line on each drum. With twin stern anchor winches and a Palfinger PK12000M foldable knuckle-boom deck crane are provided on aft deck.

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