Icelandic owners, HB Grandi, Vinnslustodin hf. and Hradfrystihusid Gunnvör, have ordered newbuildings based on two different ship designs from specialist fishing-vessel consultants and designers, Nautic and Skipasýn. Optimised for safety, operational economy and pulling power, the 50-metre-plus vessel series differ in their choice of specified propeller, aft-ship and propeller-nozzle configurations, apart from their principal design differences. The Nautic vessels for HB Grandi will be propelled by 4-bladed, 3.8-metre MAN Alpha CP Propellers, while the Skipasýn vessels will have larger, slower-running 4.7-metre, 3-bladed versions for a calculated bollard pull above 50 tons.
Styrmir Petersen, Afltækni ehf, Reykjavik said: “We have been representing MAN Diesel & Turbo for more than 20 years as sales and service agents in the Icelandic market and now we are very pleased again to see increasing activities and investments after the financial crisis and following tough years for Iceland. Additionally, it is of course both interesting and challenging for us that we will supply new MAN products and services to two state-of-the-art, Icelandic, fresh-fish trawler designs.”
High bollard pull at low propeller revolutions
Designer/consultant Skipasýn has developed the efficient 50.7-metre trawler design for Vinnslustodin hf. and Hradfrystihusid Gunnvör. In relation to the design and layout of the propulsion plant, the ship designer’s fuel-saving focus has been on the deployment of a large, efficient, 4.7-metre propeller. As a result, the 800 r/min engine (MCR) speed has had to be geared down to an optimal propeller speed of just 89 r/min. Blade-number optimisation resulted in a three-bladed configuration. At the 2,040 kW operating point, the three-bladed MAN Alpha VBS1020 propeller using the Alpha High Thrust nozzle is calculated to deliver a bollard pull above 50 tons. Both vessels will be built in China by Huanghai Shipbuilding Co. Ltd.
Reduced consumption under more operating conditions
The three Nautic-designed, 55-metre vessels for HB Grandi, which will appear with a distinctive bow design, will be built in Turkey by Celiktrans Shipbuilding Co. Ltd. As with the other series, the selected propulsion engine is MAN’s six-cylinder L27/38, accompanied by four-bladed, ducted MAN Alpha VBS 860 propeller models. A key Alphatronic 3000 control-system feature will be the tailored ‘dual-propeller load curves’ for optimising towing/trawling and free-sailing conditions.
The specified, floating-frequency concept for both trawler series increases the flexibility and economical part-load pattern. The propulsion system is able to operate in ‘shaft-alternator mode’ with reduced engine and propeller speed (within the corresponding 50 to 60 Hz speed envelope). With this part-load optimisation feature offering up to 17% lower engine/propeller speed, fuel consumption is accordingly reduced. The L27/38 engines have perfect load and low-speed characteristics for floating frequency: high torque and approx. 50% power is available at speeds reduced from the 60 Hz load point to 50 Hz.
The general propulsion management and control system specified for both trawler designs is MAN Diesel & Turbo’s new, advanced Alphatronic 3000 generation. The installations will be configured for complete control-station set-ups at the vessels’ main bridges, starboard bridge wings, aft bridges and engine-control rooms.