Norwegian fishing company Liegruppen is no stranger to innovation, and its new pelagic trawler Liafjord is outfitted with the first system of retractable foils to be delivered to a fishing vessel.
Three years ago, Liegruppen took delivery of the ground-breaking LNG-powered Libas, and even before its delivery had placed the order forLiafjord – with the same designer and with the same shipbuilder. Unlike the purse seiner/trawler Libas, Liafjord is a dedicated pelagic trawler, and Liegruppen opted not to go for LNG propulsion a second time.
Instead, Liafjord has diesel propulsion, backed up by a heavyweight battery pack to optimise energy consumption and make full use of excess energy from a variety of systems on board.
The innovation lies in the retractable bow foil technology from Wavefoil. The bow foils are seamlessly integrated into the vessel’s design, significantly reducing vessel motion and improving energy consumption in in heavy seas. This results in lower fuel consumption and emissions, while also making the vessel a more comfortable and stable working platform – while also allowing higher speeds to be maintained under rough conditions.
Wavefoil estimates that the retractable bow foils typically save 5-15% of fuel.
The benefits of bow foils have long been known, but Wavefoil is the first to develop a commercial and patented solution for foils to be retracted into a vessel’s hull. The Wavefoil system installed on board Liafjord is a WF3970 module, with a wingspan of approximately 8 metres, and a control system for foil retraction. The control system enables remote monitoring, which increases the operational safety and ensures optimal performance.
Flexible propulsion
Designed by Salt Ship Design and built at the Cemre Shipyard in Turkey, the 71.45-metre by 16-metre breadth Liafjord has a 2,100 cubic metre capacity in its tanks, chilled by a double MMC-SX RSWplant. The 720 g03/h ozone plant is from Normex and the vacuum pump system on board is a double installation with four 85kW compressors, supplied by Tendos.
The electric deck layout is from Evotec, with a pair of 120 tonne MultiSoft main trawl winches, plus a 120-tonne centre trawl winch. There are twin 170-tonne net drums, and the Evotec package includes tail-end, net sounder and auxiliary winches.
Rapp supplied Liafjord’s CP-3501E-20 electric fish pump, as well as the reels for the power cable and the fish hose, and additional accessories.
Seaquest Systems delivered Liafjord’s 4t/13m crane forward, and the 5t/13m knuckleboom crane aft is mounted on the stern gantry.
The propulsion package is a 4800kW Bergen Diesel B33:45L8P powering an integrated Brunvoll reduction gear and controllable pitch propeller with shaft and stern tube, tunnel thrusters and control system. This is a two-speed system with PTO/PTH function from a combined shaft generator/electric motor. This allows supply surplus energy to be routed to the main switchboard from the main engine in PTO mode, and in PTH mode the ship runs electrically in emergency mode.
Brunvoll’s two-speed system is designed for high flexibility with two propeller speeds for efficient operation adapted to the ship’s operating profile. This reduces 0-pitch loss to a minimum, resulting in significant fuel savings, reduced emissions, and reduced costs.
The auxiliary engines are a pair of 750eKw Yanmars, and the energy network on board included a 509kW Corvus battery pack.
Thrusters are controllable pitch Brunvoll units and steering is a Kongsberg SR722FCP system.
