CGN refits Valais with Hull Vane and bulbous bow

CGN refits Valais with Hull Vane and bulbous bow
CGN
CGN estimates that the retrofit will reduce carbon dioxide emissions from Valais by 129 tonnes per year

Swiss ferry operator CGN has retrofitted its 30-metre ferry Valais with Hull Vane and bulbous bow devices, as well as replacing its engines with new common-rail V8 MAN engines.

“We selected Valais and commissioned a ship optimisation study by means of computational fluid dynamics software, comparing several possible hydrodynamic improvements at our operating speed,” said Irwin Gafner, technical director of CGN. “In the study, the benchmark hull was compared to various retrofit alternatives for the stern, such as ducktail extensions, interceptors and a Hull Vane, which is a rather novel solution and can be described as a “spoiler for ships”. The best alternative to come out of this optimisation was the Hull Vane, promising a resistance reduction of 15 per cent. We also asked to optimise a bulbous bow for the ship with Hull Vane.”

After the study, CGN ordered the Hull Vane from Hull Vane and the bulbous bow from a local subcontractor. Both devices were then installed at the CGN Technique facilities in Lausanne, Switzerland, along with the new engines. After the launch of the vessel, ballast was added to the bow to bring the ship to the appropriate draught.

Subsequent measurements showed that the fuel consumption of the vessel was reduced by 24 per cent following the dry dock. Noise levels were also reduced by 2 A-weighted decibels (dBA) in the wheelhouse and by 6 dBA in the passenger lounge. Valais now makes significantly less waves, and the added submerged surfaces have improved the stability of the ship. The operator estimates that the retrofit will reduce carbon dioxide emissions from the ship by 129 tonnes per year.

“There are a lot of small passenger ships ranging from 20 to 100 metres in use worldwide, on rivers, lakes and servicing islands,” said Bruno Bouckaert, sales director of Hull Vane. “Because of their length and displacement, they often operate at excellent speeds for Hull Vane effectiveness, making a retrofit very worthwhile. We are very happy that CGN took this pioneering step.”

Valais has returned to service on the route between Yvoire, France, and Nyon, Switzerland, making up to 40 crossings of Lake Geneva a day.

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Alex Smith
By Alex Smith
17 July 2020

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