Cooperation Smoothes Path to Gas Powered Tugs

Sanmar, Turkey’s leading pioneering tugboat building specialist, reports that its new build contract to deliver the world’s first Liquid Natural Gas (LNG) powered escort tugs for Buksér og Berging AS of Norway, is proceeding smoothly despite it being ‘ground-breaking’ technology for the tug sector.

Sanmar’s Board Member, Ali Gürün, explained: “Cooperation between the shipyard team, the owners and designers Bukser og Berging, the classification society DNV and the Norwegian Maritime Authority is proceeding well. Some 90 per cent of the steel construction is already finished and the critical process of installing the LNG tanks and engines has been completed successfully without any hitches. The rest of the outfitting continues as planned.

“Furthermore, we do not anticipate any slippage of the original delivery schedule despite the ‘learning curve’. Both vessels will be in service by the end of this year on long term charter with Statoil ASA, the international energy company, and Gassco, the operator of the gas transportation network off the Norwegian coast.”

The LNG system has been designed by AGA Cryo and integrated with the Rolls-Royce propulsion system. This single tank LNG system has got full gas redundancy i.e. no diesel back up is required. The vessels will also be equipped with two Rolls-Royce azimuthing Z-drives.

A cleaner engine room, less waste oil and no ‘switch over’ problems are amongst the operational benefits of a gas fuelled propulsion system. Other environmental benefits with the spark ignition gas engines incorporated in the new design include 92 per cent reduced NOx emissions, 17 per cent reduced greenhouse gas emissions, 98-100 per cent reduced SOx emissions and 98 per cent reduced particulates. The system is compliant with Tier III regulations.

The vessels will measure 38m x 14.5m, have accommodation for 5 persons and achieve a static bollard pull of 70 tonnes with about 20 per cent greater efficiency than standard designs.

Furthermore, the hull and layout design has been optimised for the potential installation of 9-cylinder engines to give a bollard pull of 70 tonnes. Moreover, a DNV Classified 120 tonnes steering-force at 10 knots is not just a revolutionary result but will have considerable appeal in the escort tug market.