Danish fishing company Gitte Henning is leading the way in bringing fishing into a new, green age by contracting to build an environmentally-friendly new pelagic fishing vessel at the Zamakona shipyard in Bilbao.
Henning Kjeldsen had initially intended to withdraw from fishing after the sale of Gitte Henning to the Faroe Islands, as well as receiving offers for all his pelagic fishing rights.
‘After thinking about the future, I got cold feet about the prospect of doing nothing, and got in touch with Salt Ship Design,’ he said.
Together, he and Salt’s designers have come up with a new, green Gitte Henning incorporating a number of environmentally friendly systems, many of them new to pelagic fisheries. Throughout the design process and in the choice of equipment, the focus has been on improving quality of the fish and reducing emissions through reduced energy consumption and efficient power production.
This new Gitte Henning it is the fourth design collaboration between Henning Kjeldsen and the Sandvik family, and this will be the second Salt-designed Gitte Henning. This latest vessel to carry the name will have an overall length of 87 metres with a 20 metre beam.
The conventional single large propeller has been replaced by two propellers and a twin-skeg hull design. Extensive flow analysis and model tests demonstrate that this a more efficient stern and propeller design, providing better towing power and lower fuel consumption while trawling. Large rudder angles are often needed on conventional fishing vessels to maintain course, even in moderate weather conditions – so two propellers provide the opportunity to steer the ship with minimal rudder impact, which reduces additional energy requirements during sailing and trawling.
The twin propellers are powered by two electric Permanent Magnet (PM) motors to be supplied by Brunvoll. This type of motor has less electrical loss and can operate significantly greater efficiency than conventional electric motors throughout the power range, particularly at low engine speeds. Low propeller rpm has the advantage of ensuring better propeller efficiency at typical loading and there is no need for a reduction gear and consequent mechanical loss, plus noise levels are reduced.
All winches are also powered by PM motors for reduced loss and optimal operation. Evotec electrical winches provide the opportunity to regenerate energy when shooting away that would otherwise be lost. This energy is available to other systems on board and can be routed to propulsion or RSW cooling. Opting for electrical winches eliminates the requirement for hydraulic oil in large volumes on board.
The new Gitte Henning’s innovative RSW layout is arranged in a new way that gives inner surfaces of the tanks a smooth finish with no obstructions or sharp edges. The design is for four independent Johnson Controls cooling systems, with four RSW tanks per facility. This provides a more efficient cooling process by only cooling sections of the tank volume as required, resulting in an energy-saving cooling system. In addition, the capacity of the C-Flow vacuum system for unloading has been increased by 40% compared to normal unloading capacity. SeaQuest has been chosen to supply the electric fish pumps.
All electric motors, from winches to pumps, are frequency controlled. This will provide a more customised power supply and hence reduce the overall energy consumption.
Energy for the propulsion system is to be provided by five Yanmar diesel generators, located in two separate engine rooms for the best possible safety and working environment, supplying the propulsion PM motors and all other energy consumers on board. All generators are equipped with catalytic converter (SCR) to reduce emissions and meet new and stricter IMO Tier III requirements.
Energy requirements on board a pelagic trawler fluctuate significantly with varying weather, operational conditions, cooling requirements, speed and other factors, and the number and size of generators are chosen to optimise the power balance based on the vessel specific operational profile and ensure that the diesel engines have optimum operating conditions and thus high efficiency.
To further improve the operating conditions of the diesel engines, Henning Kjeldsen has chosen to invest in a large battery pack that support the generators when the load is high and recharges when load is low. Regenerated power from the winches during trawling also helps to charge the battery pack.
In this way, the diesel engine will not encounter large load variations, which in itself results in a fuel reduction of roughly 10%, based on the experience with other diesel-electric vessels, as battery usage ‘shaves’ the load peaks.
The batteries are located in a separate room, thus providing an additional source of emergency power in addition to the diesel generators in the two engine rooms. In addition, they will significantly reduce noise and emissions in port.