VIDEO: First Hull Vane Retrofit on an OPV
(With extra pictures) The Offshore Patrol Vessel (OPV) Thémis from the French Coastguard (Affaires Maritimes) is the first patrol vessel to receive a Hull Vane, an underwater wing that reduces the ship’s resistance.
The vessel’s hydrodynamic upgrade was carried out at CMN Shipyard in Cherbourg, France.
Comparison of the sea trials with Hull Vane on 13 June with the benchmark sea trials – conducted in January in exactly the same conditions – showed a reduction in fuel consumption of 18% at 12 knots, 27% at 15 knots and 22% at 20 knots. The top speed increased from 19.7 knots to 21 knots.
After the order for the Hull Vane, the device was specifically optimised by Hull Vane BV for the Thémis, which differs from the standard CL52, but the results were very similar.
Bruno Bouckaert, sales director of Hull Vane BV: ‘The Hull Vane is basically a patented application of a hydrofoil on ships where you would not expect one: steel and aluminium vessels that operate in the area between full displacement and planing mode, what we call fast displacement vessels. It works by creating a lift force from the upward flow at the stern. This lift force is angled forward and therefore not only lifts the vessel, but also pushes it forward. The Hull Vane also reduces the stern wave, which is a form of energy loss, which we try to minimise.’
OPV to Become Major Market for Hull Vane
The Hull Vane for Thémis is the eleventh unit built, but it is the first one retrofitted on an OPV, a ship type which Hull Vane BV expects to become one of their major markets. About a dozen studies and model tests have indicated similar savings percentages on patrol vessels ranging from 25 to 108 metres.
The Hull Vane was built of steel in the Netherlands and was transported to Cherbourg by truck. CMN was in charge of the installation and the structural integration, including a lengthening of the divers’ platform. It is the first time the Hull Vane has been applied in France.
The influence of the Hull Vane can be clearly seen in the modification of the wake behind the vessel, as shown in the pictures in the album below, which show the wake before and after the retrofit. The results match very closely the performance predicted in CFD, by Hull Vane BV’s sister company Van Oossanen Fluid Dynamics. Model tests were not done for this project to save on cost and time.
Thémis has a top speed of 21 knots, but most of the time it sails around 12 knots to save fuel. Taking into account the operational profile of the vessel, the annual savings amount to 20% of the fuel consumption, and of course the same percentage in emissions of CO2, particulate matter, NOx and SOx.
Picture (top) by CMN.
Please see the album below for more pictures. Click the pop-out link to view them in their proper dimensions.