The greening of fast cats - a new wave of catamarans

Incat maintains that the 130m long, 31.9m wide Ecoship 130’s environmental credentials are overwhelming. Using fuel efficient marine diesel engines, the new design is optimised for speeds of up to 30 knots at which speed the vessel will be operating in displacement mode. Consequently the hull form is optimised for displacement speeds with the longitudinal centre of buoyancy (LCB) centre moved further forward and less transom immersion enabling drag to be kept to a minimum by use of retractable or low profile appendages.

Dual level bow and stern loading will reduce port turnaround times to 15 minutes when matched with efficient port facilities. The dual levels allow heavy vehicles to transit at the same time and separate to the cars above, ensuring car passengers are isolated from trucks and commercial vehicles.

Speed reduction is beneficial in terms of reducing emissions and improving efficiency, but the real effectiveness of such a scheme depends on the possibility of reducing port time. This means that the role of ports is of paramount importance for overall ship emissions. The dual level bow and stern loading of the Ecoship 130 will help develop an efficient on/off loading capacity.

Propulsion system

The Ecoship 130 is powered by four MAN 20v 28/33D diesel engines, each rated 9,000kW at 1,000 rpm. This engine has been made first choice because of proven durability, efficiency, low noise and low maintenance costs. Low fuel consumption means burning less weight of fuel per cargo tonne per hour than other high speed catamarans.

The MAN engines will meet all current and future requirements for low NOx emissions set out by IMO, ensuring the Ecoship 130 remains environmentally friendly throughout its working life.

The most stringent low noise emission standards will be addressed through a series of engine room innovations, reducing machinery noise while the ship is alongside and ensuring interior noise levels are below recommendations.

The importance of sub 30 knot speeds cannot be overstated since it means that the vessel is designed as a ship capable of sustained economic service with up to 1,700 tonne load at 90% MCR. Lower loads with reduced power, e.g. 200 tonnes, require only 50% MCR.

Engine power is converted to propulsive thrust through a new design of waterjet from Wärtsilä. The new LJX waterjet offers, in comparison with other waterjets, a 25% reduction in mounting flange diameter, a 10% overall weight reduction and a 35% increase in cavitation margin, all contributing to the lighter seaframe and a more efficient fast ship.

With a 1,500mm diameter high flow impeller and inboard layout for steering and reversing hydraulic cylinders, the new design results in lower vibration levels, less noise and greater vessel manoeuvrability, further extending the environmental credentials of the Ecoship 130.

To aid the vessel in slow speed manoeuvrability and berthing, bow thrusters integrated with a Wärtsilä waterjet control system will be fitted. The combination of bow thrusters and high mass flow jets will reduce the power required to manoeuvre, thus reducing impact on the seabed and marine life within the port.

Green solutions

Solar panels can be mounted on the superstructure roof, using light energy (photons) from the sun to generate electricity to charge batteries and run minor electrical services. The modular nature of solar panels allows the operator to determine the optimum number of units and therefore power generated for the ship’s operating profile.

Wind turbines mounted on the superstructure roof will capture the wind flow across the ship to convert wind energy into electrical power to augment the power required by the electrical services to further reduce the ships dependency on the diesel powered generators. Unlike solar panels, the wind turbines remain operational at all times of the day or night and also alongside the wharf when the ship is stationary.

Thermal reductive glass has the potential to reduce external heat loads on the passenger space from direct sunlight and outside temperatures. Reductions of up to 30% can be expected through multi layer panels and increasing glass angles.

A water heat recover system using heat from the main engine exhausts will provide additional passenger cabin heating in colder climates, reducing the dependency on the air conditioning units, and heat the domestic water used in the hand basins, bars and galley while the vessel is operational.

The Ecoship 130 will be coated with a toxin-free antifouling system which will continue to provide protection against marine growth for up to two years, ensuring marine organisms are not transferred to different ports.

To enable the carriage of high cost perishables the Ecoship 130 will be fitted with at least 20, 30A power sockets for plug in refrigerated containers. By using the ship’s electrical power, the refrigeration machinery can be turned off during the voyage reducing the emissions produced by the refrigeration plant.

Emerging LED lighting technology has the potential to reduce electrical loads, reducing generator sizes and fuel consumption reducing airborne waste. There is also an increase in the service life of fittings leading to a reduction in replacement cost and the solid waste produced by the vessel.

Interior solutions

Interiors can be tailored for a single class operation or encompass both business and tourist class areas. The design of the interior makes use of weight saving features required in high traffic areas while maintaining a safe, sturdy, easily cleaned and maintained vessel. The materials used on the Ecoship 130 will meet the IMO regulations for fire/flame retardment, smoke development and toxicity levels.

Passenger comfort is further enhanced due to the large size of the vessel since the increase in length, breadth, weight, all contribute to a smoother and more comfortable ride, reducing the MSI (motion separation index) index of the 130m to almost half that of Incat’s 98m wave piercing catamaran.