'Le Boreal', designed for mega-yacht cruising comfort

30 Sep 2010
Le Boreal undergoing sea trials

Le Boreal undergoing sea trials

When the French cruiseship company Compagnie du Ponant approached Fincantieri with a new and innovative project to develop, design and build a mega-yacht style cruise ship, the Italian shipbuilder devoted its technical expertise to turn dream into reality when the order was placed for two such vessels in 2008.

The first in the two-ship series, Le Boreal, was delivered in April this year from the Ancona shipyard which is also building the sistership, L’Austral, scheduled for delivery in May 2011. This custom-built vessel claims to revolutionise small ship cruising with a new generation of ship design and technology and unprecedented standards in elegance and comfort. Measuring 142.1m length overall, 18m wide and a draught of 4.7m, the 10,700gt newbuilding has a flexible passenger capacity from 224 up to 264 accommodated in up to 132 outside suites/staterooms on six decks.  

The diesel electric power plant comprises four Wärtsilä medium speed 8L20 gensets each with power output of 1,480kW at 900rpm. These deliver power to the two 2,300kW Indar induction motors each of which drives a Wärtsilä 3.1m diameter FP propeller to give a service speed of 16 knots at 4,200kW. The vessel is fitted with an 800kW Rolls-Royce bow thruster, has a DP capability, is built to ice class 1C and has the highest BV Comfort classification.

The electric propulsion system is designed for fuel efficiency, as well as enabling the ship to cruise with little vibration and significantly less engine noise to provide a smooth, quiet and comfortable passage. The ship meets the latest ‘Cleanship’ standards and operates an advanced navigational dynamic positioning system.

Onboard comfort is enhanced by Rolls-Royce Aquarius 100 retractable stabilizer system equipped with 8m² stabilising fins.

Recreation, fitness and wellness facilities include a swimming pool, spa, Turkish bath-style steam room, full range of fitness equipment and open-air sun deck. The ship is equipped with Zodiac landing craft, in addition to two large tenders.

The structure of the stern and the propeller parameters have been analyzed with particular care for the position of the main restaurant directly above the propellers. The final vibration predicted levels were calculated using a global finite element model and the vibration measurements performed onboard during sea trials show a good correlation with calculations.

The propeller designed for the newbuilding followed a new procedure which does not consider the hull wake as a fixed input data, but as an integral part of the propeller design loop. The wake optimisation was carried out in parallel with the blade design and this was a decisive factor leading to the complete suppression of the cavitation on the blade surface and the cavitating tip vortex.

The specific power per square metre for the propeller was very low and this factor allowed the designers to achieve a very high efficiency and low pressure values. The fixed five-bladed configuration proved to be the best compromise between efficiency and propeller load. During testing carried out at the vacuum tank of Marin, pressure values in the order of 0.5 kPa were measured giving the ship a propeller excitation lower than those required for a high comfort mega-yacht.

All the equipment installed was taken into account to ensure that it would never cause a problem from a noise and vibration point of view. The ship is equipped with two propulsion induction motors that are believed to guarantee that no pure tones are transmitted through the structure into the upper deck public areas. The four gensets for propulsion and hotel load are mounted on a common sub base with a system of mass dampers.  

The concept of comfort on board a vessel at a high level of luxury extends beyond noises coming from machinery and an important aspect is the level of privacy guaranteed between cabins. This has been achieved using a double panel system giving superior noise abatement with lower weight of partition compared with a single panel.

All the work done in the preliminary design phase, both from hydrodynamic and structural points of view, has been confirmed by results achieved during sea trial measurements, thus obtaining the challenging highest grade of Bureau Veritas Comfort Class and confirming Fincantieri's claimed high quality standards of technical and shipbuilding capabilities in the luxury cruise vessel field.

Links to related companies and recent articles ...

Fincantieri SpA

view more