Evolution for P&O cross-Channel ferries

The Channel Tunnel was supposed to kill it. But in the years since the Channel Tunnel opened, trade on the short-sea crossing from Dover in the UK to Calais in France has boomed. While roro demand out of Dover and other Kent ports to Ostend, Zeebrugge and Boulogne, etc. has contracted, demand on this shortest Channel crossing ? to Calais ? has grown to the extent that P&O Ferries, the major operator on the route, is now expanding capacity on it.

The company has committed to the conversion of two freight roros into ropax ferries at German shipyard Lloyd Werft. The ships ? European Pathway and European Highway ? were built in the early 1990s at another Bremerhaven shipyard, Schichau Seebeckwerft. They were built with 1,860m of roro lanes, equivalent to capacity for 124 lorries, and a forward superstructure containing 81 cabins and various other facilities for up to 200 passengers. The ships had been operated until late last year between Dover and Zeebrugge in Belgium, one of the routes experiencing shrinking demand.

When the two ships complete their refits ? and enter service renamed as Pride of Canterbury and Pride of Kent respectively, one as this issue goes to press in late April, the other later this month (May) ? they will have roro lanes for up to 115 lorries, or 640 cars, and a superstructure extended aft with facilities for 2,000 passengers.

The £50 million ($77.5 million) conversion of the two ships is known within P&O Ferries circles as the Darwin-project (evolution of the species). Lloyd Werft won the contract having seen off competition from A&P Tyne (UK), Stocznia Remontowa (Poland) and SSW (Germany ? the yard that built the ships, albeit under different management). Lloyd Werft sub-contracted SSW to undertake the steelwork design. Work on the first ship commenced slightly ahead of the second, in December last year.

In setting the configuration for the new ships, P&O Ferries in collaboration with P&O?s architectural design boutique Three Quays Marine Services, adhered to a design brief that listed requirements such as for: a 2,000 passenger day ship; wide alleyways; shops and lounges located to minimise congestion; ability to close off areas at night; optimal passenger space arrangement; and for a live aboard crew of technical, deck and key hotel services staff.

The extension of the superstructure from deck seven and above, to run about 75 per cent the length of the ship, has provided the space to meet many of these requirements. It has involved adding about 1,400t of steelwork per ship and raised significant challenges related to stability, windage, evacuation, noise and vibration.

Stability

P&O originally hoped to undertake a conversion that would give the ships two-and-a-half decks for passenger facilities. However its initial stability calculations showed that the hull could not control the extra weight and windage this would involve, so it settled on a configuration with two decks of passenger facilities, amounting to about 5,000m2, topped by a structure containing crew facilities including 50 new crew cabins.

Damage stability tests were re-run for the revised design with all the Stockholm Agreement on

Stability

approvals undertaken at Strathclyde University?s model test tank in Dumbarton, Scotland. The potential capability of the sub-division draught has increased from 6.25m moulded to 6.4m moulded as a result of the conversion, which corresponds to 600t displacement. There is a restriction on the freight that can be carried, but P&O says this is no worse than other ships in the Dover to Calais fleet. Effort was made to keep weight forward as much as possible to avoid giving the ship a stern trim.

Windage

The ships? original manoeuvrability outfit comprised twin high lift rudders behind CP propellers at the stern, complemented by two 1,200kW bow thrusters. However P&O had adequacy concerns over the ability of this outfit to handle the extra windage of the enlarged superstructure. As a consequence, thrust has been increased at the bow from 170kN to 240kN through the replacement of the bow thrusters with larger 2,000kW Lips units.

This in turn has required new, larger output (2,200kW) shaft alternators to be fitted in order to supply the required power to the bow thrusters. The new bow thrusters are driven through a 6.6kV system with new changeover panels that allow either bow thruster to be driven by either shaft. A new switchroom containing the 6.6kV equipment has been located in a space formerly occupied by a freshwater tank at the stern of deck 2. Tests run on the Rembrandt simulator at BMT Seatech determined that with the new bow thrusters fitted manoeuvrability at the stern was not as good as at the bow, so the rudders have been changed to spade flap units.

Machinery

The machinery in the main engine room, four 5,280kW Sulzer 8ZAL40S medium-speed diesel engines with clutches, flexible couplings and single reduction gearing to twin screw shafts, remains as per the original configuration.

The additional electricity that carrying and catering for up to 1,800 more passengers will require is met through the addition of an extra auxiliary diesel generating engine ? a 1,440kw Wärtsilä Vasa 8L20C. This has been located within the existing machinery space alongside the three original 1,150kW sets. A new Aalborg auxiliary boiler has also been fitted on Deck 2 of the auxiliary engine room to supply the greater quantity of hot water that the expanded passenger capacity ships will require.

Exhaust gas scrubbing

Also fitted within the auxiliary engine room of the second ship, Pride of Kent, on the port side underneath the engine control room, is sophisticated filtration equipment for a new exhaust gas scrubbing system. This is fitted as part of a joint project between P&O and BP Marine. The system is intended to reduce the engines? SOx emissions by 95 per cent, particulate matter emissions by 80 per cent and NOx emissions by 10 to 20 per cent. The first ship, Pride of Canterbury, has been prepared to have the same DME-manufactured kit fitted. It isn?t fitted yet because the eco-silencers couldn?t be made in time, says P&O.

In preparing the first ship for the installation, two racks have been created which slot into the funnel. These currently contain the original silencers, plus one for the additional auxiliary engine. They are designed such that eight new eco-silencers can be put into racks of equal dimensions and retrofitted onto the exhaust gas system with relative ease. Seawater piping for the system has already been put in place in preparation for the retrofit. Racks fitted in the second ship already contain the eco-silencers, which are marginally fatter than the conventional silencers.

The system works by bubbling the exhaust gases through seawater in the eco-silencers. This removes pollutants from them before they are emitted from the stack. The seawater containing the scrubbed pollutants passes back down to the filtration equipment in the auxiliary engine room. Here pollutants are removed and sent to a sludge tank located in the heeling room. The circulation pump for the silencers is located in the main engine room.

The eco-silencers for the auxiliary engines are fitted with dimple jackets – cloaks through which the seawater passes ? which recover waste heat. This, says P&O, helps ensure there is no negative impact on fuel consumption or the efficiency of the exhaust gas system. The system is similar in principle to that used on tankers to create inert gas for the cargo tanks when unloading. The cost of fitting the complete system to one ship and preparing both ships for its installation has been about $3 million.

The system is being fitted largely in response to proposed EU amendments to EC Directive 99/32, which are intended to push through anti-pollution measures outlined in Marpol Annex VI. P&O anticipates the system will reduce sulphur emissions on Pride of Kent by 800t per year.

P&O argues that the environmental benefit of using lower sulphur fuels is limited. The eight-ship Dover fleet currently operates on two per cent sulphur fuel. Switching to one-and-a-half per cent sulphur fuel across this fleet would bring about a reduction of about 1,500t per year of sulphur emissions, it says.

The company wants to be allowed to offset the 1,600t sulphur reduction of the two ships fitted with exhaust gas scrubbers against the rest of its Dover fleet and thus continue to operate on two per sent sulphur fuel. It adds to its argument that dealing with sulphur onboard ship makes more environmental sense than using residue reduction equipment in refineries.

Evacuation

The extension of the superstructure has required two additional stair towers and two extra elevators to be fitted to provide vertical movement between all the decks. Each of the three fire zones containing passenger facilities has a stair tower running from top to bottom. Each also contains two 450-person marine evacuation systems ? one port, one starboard ? on Deck 7 (the lower passenger deck).

The no-lifeboat solution, in favour of the RFD Marin-Ark MES system, was supported by the UK?s Maritime & Coastguard Agency. It is the first time that a roro passenger ferry operator has opted for a MES as the (virtually) exclusive means of evacuation. The ships also have four Fassmer fast rescue boats. Their launch davits, on Deck 5 and 7, are also able to launch lifeboats for passengers unable to use the evacuation chutes, such as the disabled.

On Deck 2 a central stores area has been created through a change in the subdivision and placing a B/5 bulkhead in a previously void space. The stores are loaded from Deck 3, the lower car deck, through an elevator. A passenger lift and service lift have been switched in this area to account for the ships? revised lay-out.

Roro decks

The upper car deck, Deck 5, has been complemented by the addition of a mezzanine platform capable of accommodating up to 70 cars on the starboard side. This addition is set against a loss of some roro capacity through siting two of the fast rescue boats on this deck. The ramps onto and off the mezzanine deck are not full width allowing it and the deck below to be loaded/unloaded simultaneously. The mezzanine platform can be hoisted up to enable the accommodation of trucks on the starboard side of deck 5, although P&O expects it to remain down for most of the time.

Noise and vibration

Efforts to minimise engine-induced noise and vibration from those areas most susceptible to it, at the stern, include modified steelwork, the fitting of a visco-elastic membrane to the flooring, the synchronisation of each engine onto each shaft and the precise mounting of exhaust systems. The eco-silencers are also said to give noise attenuation and smell benefits. The engines are rigidly mounted, which doesn?t help the situation, but P&O says to resiliently mount them via a retrofit is virtually impossible.

Public areas are configured such that the most exclusive spaces ? such as the Club Lounge and Brasserie ? are located forward, furthest from noise and vibration sources. These areas also benefit from the provision of a new forward observation section. The retailing area and truck drivers lounges are located midships of the passenger accommodation decks, with less exclusive cafeterias and bars located aft. A gangway runs aft on Deck 7, the lower passenger deck, to facilitate loading and unloading of foot passengers in Dover. The interior of these spaces was designed by the consultancy group FCG.

Simon Pollard, a naval architect based at P&O Ferries Dover office, was in charge of development of the conversion concept. On-site supervision of the project was overseen by Neil Farquhar. Nick Holness, at group headquarters in London, managed the exhaust gas scrubber project.

The new Pride of Canterbury and Pride of Kent are replacing two smaller ships of the same name on the Dover to Calais service.