Stena’s new formula for ro-pax market
Six E-Flexer ro-pax vessels have now been contracted in China for fleet modernisation and service upgrades by north European short-sea specialist Stena Line, writes David Tinsley.
With the recent confirmation of an order by Stena RoRo for a sixth ro-pax ferry of the E-Flexer concept, the Swedish group is now close to realising its originally envisaged programme of eight ships of the new generation.
The series has been entrusted to the AVIC Weihai shipyard in China, using a design which, it is claimed, will rate the ferries as the most efficient worldwide, while offering a high degree of flexibility as regards operating profile, route or service allocation, and tailoring to clients’ specific needs.
The promised versatility is already expressed in the mix of deployments planned for the six vessels booked to date, which entail not only tonnage renewal by Stena Line, but also long-term charters to other prominent players in the short-sea ferry market.
Each newbuild will offer a ro-ro capacity of 3,100 lane-metres plus provision for up to 1,000 passengers. Deliveries are scheduled from early 2020 onwards. Primarily as a consequence of economies of scale, advances in propulsion technology, and an erudite approach to power, propulsion and underwater design, the vessels will produce about 25% less CO2 emissions per freight unit than existing ro-pax ferries.
Although specified with diesel machinery, the first five newbuilds have been laid out and will be certificated to be ‘gas ready’, so as to facilitate any future conversion to LNG or methanol fuel. It is understood that the sixth ship will have a dual-fuel installation from the outset. In addition, the engineering design for the E-Flexer type provides options for retrofitting scrubber plant or selective catalytic reduction(SCR) systems as means of combating SOx or NOx emissions.
Technical consultancy Deltamarin, founded and headquartered in Finland, but owned by the Chinese shipbuilding contractor’s parent AVIC group, has developed the design and is supplying the comprehensive engineering, procurement, construction and management (EPCM) package.
Within main dimensions of 212m length overall and 27.8m breadth, a drive-through configuration has been chosen to speed port turnarounds on busy short-sea crossings. The primary power installation is based on two engines, rather than the four-engine solution common to high-capacity ro-pax ferries, and is distinguished by arrangements that make efficient provision for a larger speed range and wide variations in load intake.
Anticipated maximum speed is 22 knots from two MaK medium-speed engines driving two controllable pitch propellers via reduction gears. The complete propulsion driveline is being supplied by US-owned, Hamburg-based Caterpillar Marine through Scandinavian dealer Pon Power. An unusual feature is the nomination of fully-feathering propellers. At speeds under 18 knots, economical operation can be maintained on a single propeller, with the other unit feathered so as to reduce resistance.
The main machinery in the ‘gas-ready’ ferries will be 12-cylinder, V-type M43C diesels, individually rated at 12,600kW. DNV GL’s Gas Ready notation applicable to the ships defines a level of preparedness for operation on or conversion to LNG fuel, and affords guidance as to the measures need to achieve the transition. Caterpillar’s MaK portfolio includes the proven dual-fuel derivation of the M43C series, the M46DF design, which has a slightly wider bore and which delivers a slightly lower output at the same running speed, while achieving IMO Tier III compliance in gas mode. MaK’s DF technology can be applied through in-situ modification of the standard diesel engine.
The sixth newbuild, destined for charter to Brittany Ferries, is likely to be equipped with LNG-capable, DF machinery from the outset. Other characteristics of the E-Flexer generation include the unique shape of the hull with an optimised bulb, plus special openings for the bow thruster tunnels, so as to reduce resistance and improve hydrodynamic performance. The rudders have been designed to recover energy losses from the propellers, and the stern has been formed in such a way as to minimise wave making.
The ships will also be accredited with DNV GL’s TMON optional notation, covering the modalities for condition monitoring (CM) of shafts, bearings and the lubricant system. The CM-based survey process offers potentially unlimited tailshaft withdrawal intervals for inspection purposes.
Through the investments in the E-Flexer series, the Stena Group is not only building a future, long-term platform for areas of Stena Line operations, but is also responding to new and evolving business opportunities in the wider ferry market.
Initially, the indications had been that the first four newbuilds would be assigned to Stena Line’s Belfast hub, a primary element of its Irish Sea network. In fact, the first ro-pax is destined for the company’s Holyhead/Dublin crossing, linking the British mainland with the Republic of Ireland. The second and fourth vessels will be allocated to the Belfast/Birkenhead run, while the third ship has been assigned on long-term charter to Brittany Ferries for service between southern England and Spain.
Under charter to DFDS, the fifth in the series from China will be phased into the intensively utilised, Anglo-European service corridor across the Strait of Dover, while the newly-booked sixth ship will be the second E-Flexer to be deployed by Brittany Ferries.
Portsmouth is Brittany Ferries’ UK hub and will serve as the base for both of the chartered ships, to support growing traffic on the long-haul routes to Santander and Bilbao in northern Spain. Secured on bareboat terms of five and 10 years, with effect from respective completions in 2020 and 2021, the E-Flexers will supersede the French operator’s Baie de Seine and Cap Finistere. The deals carry purchase options. DFDS also has an option to buy its E-Flexer at the end of her 10-year charter commencing in 2021 and has yet to announce whether she will be placed on Dover/Calais or Dover/Dunkerque service.
Keel-laying for the first of the sextet took place at the AVIC Weihai yard in February this year, with a view to the vessel being phased into Stena Line’s Holyhead/Dublin connection at the beginning of 2020. The two other newbuilds slated for the buoyant Irish Sea freight and passenger market, the second and fourth in the production run, are due to be brought to bear on Stena’s service between Belfast and the 12 Quays Terminal at Birkenhead, on the Mersey, in the spring of 2020 and early 2021, respectively.
Internal configuration and interior design will vary throughout the E-Flexer series in accordance with operators’ specific requirements. For instance, the ships bareboated to Brittany Ferries and scheduled to make longer overnight passages, will be fitted with about 300 passenger cabins plus around 36 for freight drivers, while the Stena Line ferries will have 175 cabins. The change will be accommodated by replacing the dedicated car deck with passenger spaces. The variant for DFDS is expected to have a minimal number, or no passenger cabins at all, due to the short crossing time on the Dover routes.
The Stena Group has a long track record in devising new concepts of ro-ro ferry conducive to series production, lower unit costs, and a wide field of applicability. This reputation dates from the early 1970s, when 11 trailerships of the Stena Searunner class were ordered from Hyundai Heavy Industries in South Korea. The Searunners proved to be one of the most successful and long-serving designs ever constructed, and were the subject of numerous adaptations and conversions.
2017 was a record year for Stena Line on the Irish Sea, whereby total freight carryings on the various routes surpassed 800,000 units.
PRINCIPAL PARTICULARS - E-Flexer
3,100 freight lane-metres + 120 cars
Ro-ro freight decks
Main engines(first 5 ships)
2 x 12,600kW
Stena E-FLEXER programme
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