More than economy: Hull Vane installation on RPA-8
The savings from the Hull Vane were designed into the latest patrol and inspection boat for the Port of Rotterdam “from the very beginning”.
So explains Hull Vane’s Bruno Bouckaert, gaining the vessel both efficiency and Seawork’s Vessel Design and Construction Award.“Our CFD analysis and the model tests at Marin showed us the energy savings came in between 20% and 29% at a speed range from 10 knots to 20 knots,” he explained.
Combined with a modest hybrid unit, it meant installed engine power could be dropped by 40% in comparison with its predecessor, along with smaller exhaust systems, engine room ventilation and even a lower capacity fuel tank for the given range resulting in a lighter boat overall and saving more on the downsized engines than the price of the Hull Vane itself, says Mr Bouckaert.
The Fast Displacement Hull Form of the 25m RPA-8 (another innovation from the original Van Oossanen office), combines with the Hull Vane to avoid ‘hump’ speed which means pace can be manipulated efficiently. Most importantly, there’s only a minimal wake throughout the range, he explains. “Rotterdam actually has a station that measures the wave wake as vessels pass: the previous patrol boats, now 16 years old, create waves of about 60cm at normal patrol speeds,” he says. “The port does get a lot of complaints from the heavily loaded cargo vessels as the wash comes over their freeboard.”
“So, in the tender Rotterdam specified 40cm maximum wave at 20km/h (11 knots), but this new patrol boat only created waves of 29cm: it’s down to under half that of the port’s other patrol vessels,” says Mr Bouckaert.
The boat was handed over from the Kooiman yard early this year, but apparently not to everyone’s immediate approbation: “The RPA-8 sails very level and it also creates only 49 dB when it’s running,” explains Mr Bouckaert. “One of the harbour masters told me, ‘we don’t get the same feedback, we actually have to read the speed off the display’. I told him to switch on the intercom in the engine room to hear what the engines are doing. Two months later I asked him how that was going but all he said was, ‘Are you crazy? We like the quiet’.
