Gas propulsion for tugs and offshore support vessels (OSV) was high on the agenda at yesterday’s Saudi Aramco-sponsored Global Workboat Technology Forum.
Sanmar’s Tamer Geckin, an electrical engineer, revealed details of the world’s first LNG-fuelled tugs nearing completion for Bukser ad Berging AS at the Turkish yard.
The 35m azimuth stern drive tugs, built to DNV class, will incorporate Rolls-Royce propulsion systems and will have a bollard pull of 70 tonnes.
They are to go on charter to Statoil and will operate at the state energy firm’s gas terminal in Kärsto, Norway.
Meanwhile, Terje Nordtun, a project manager in Wärtsilä Ship Design, outlined the benefits of dual-fuel propulsion systems for use on board OSVs.
Hybrid systems made very good sense for such vessels, he explains, because of their wide-ranging operating profile. The fact that offshore craft spend as much as 60% of their time operating at low loads reinforced the need to optimise engine performance and therefore fuel consumption at low engine output.
However, incorporating gas propulsion into such hybrid systems had various additional advantages including cheaper fuel and lower emissions.
The company delivered its first dual-fuelled OSV in 2003 and has, since then, accumulated more than 30 years of vessel operating time using gas as a fuel. These propulsion units have proved to be very reliable and safe, Nordtun told delegates, with no incidents and no reported off-hire of any vessel caused by its gas operation.
A total of 22 LNG-powered OSVs are either in operation or on order and 19 of these have Wärtsilä dual-fuel engines. Ten of them were designed by Wärtsilä Ship Design.
Seatrade, October 3, 2013