A special hull vane – a kind of underwater spoiler – means that the vessel produces fewer waves, which has a positive effect on fuel consumption. It is also better for the quays and other ships along the patrol boat’s routes, which can be damaged by heavy wave action. The hull is made from aluminium. Aluminium is three times lighter than steel, meaning that the RPA 8 consumes less fuel.
RPA 8 isn’t the only hybrid patrol vessel that can soon be seen moving through the port area. Once RPA 8 has been taken into operation in September, work will start on RPA 10 and 11. These existing vessels will be converted so that soon they can also be powered by a combination of diesel fuel and electricity.
Half power or 'full steam ahead'?
Is there an emergency? Full steam ahead! Good news for the diesel engines. Because they’re made to work hard: diesel engines operate best at full capacity. And this also reduces the emission of pollutants like CO2 and particulates. These are lowest, relatively speaking, when the engine is going full out. The ‘problem’ is that usually, patrol boats move at a calm pace through the port area. Which means that the diesel engine is running at half speed and is relatively polluting. The solution? A hybrid propulsion system that allows you to operate with optimal efficiency at low cruising speeds.
For technology fans: hybrid in a nutshell
When the engine is in hybrid mode, diesel engine D is powered off and uncoupled. Diesel engine B supplies 85% of the power used by propeller 1. In addition, the engine allows electric motor A, which is connected via the propeller shaft, to serve as a generator for electric motor C. This motor powers propeller 2. The maximum speed in hybrid mode is 23 km/h. The remaining electricity generated by A is used to power the boat’s on-board equipment (E). Total fuel savings: 15-20%. Resulting in lower CO2 and particulates emissions.
With its innovative technology, RPA 8 saves roughly the same amount of energy per year as is consumed by 65 households. This also means far lower CO2 emissions – equivalent to the annual CO2 uptake of 8,088 trees.