(With video) Shipyard Kooiman recently started building a new 25-m patrol vessel for the Rotterdam Port Authority. The Hull Vane will be one of several innovations to improve efficiency.
The principal focal points for the vessel were complete life-cycle costs, a minimal amount of emissions and a minimum of wave formation. The vessel is to be delivered in the summer of 2017.
FDHF and Hull Vane
Shipyard Kooiman contracted Van Oossanen Naval Architects for the hull design. The design which best suited the operational profile – a rarely used top speed of 30 km/h, and a normal cruising speed of 20 km/h – is a combination of two of Van Oossanen's patented innovations: the Fast Displacement Hull Form (FDHF) and the Hull Vane, winner of the Maritime Innovation Award in 2015.
The FDHF allows the vessel to stay in displacement mode at high speeds with almost no running trim, and the complete absence of a “hump speed”. The Hull Vane, a hydrofoil-like appendage fixed to the transom, generates hydrodynamic lift angled forward. Self-propelled model tests at Marin showed that the Hull Vane reduces the required propulsion power – and thus fuel consumption – by 25 per cent at 20 km/h, 29 per cent at 27 km/h and 22 per cent at 35 km/h.
Generated Waves
The Hull Vane also impacts the vessel's wave profile. Marin measured both the wave pattern immediately behind the transom and the waves at a distance. The Port of Rotterdam insisted on low wave generation: at 20 km/h, the generated wave at 30 m from the boat should not exceed 40 cm (significantly below the wave generated by the current fleet). The model tests showed this height to be only 7 cm for the boat with Hull Vane and 10 cm for the boat without Hull Vane.
Emissions
Reducing resistance means consuming less fuel and therefore reducing emissions. With 350 sailing days per year, the Hull Vane on the RPA-8 reduces CO2 emissions by 162 tons. In addition, Shipyard Kooiman was able to install a smaller propulsion plant (736 instead of 939 kW), with benefits such as cost saving, reduced ventilation requirements, reduced exhaust systems, a lower noise level and more space in the engine room.
Hybrid Propulsion
For efficient patrolling at low speeds and a reduction in engine running hours of 40 per cent, the RPA-8 will have a parallel-hybrid propulsion installation from Holland Ship Electric. This system allows the boat to be sailed in diesel-electric mode up to 25 km/h on one of the main engines, or with both main engines engaged in diesel-direct mode from 25 km/h to 35 km/h. The engines are always properly loaded, which means more efficient combustion.
The video below shows a test of the RPA 8 at Marin.
