Developing an entirely bespoke large new ferry is an expensive and resource intensive task. Multiple years of work often take place before any order is placed with a shipyard. Operators will usually ask a number of different parties to provide a concept design based on outline requirements so that the operator can assess different options and select the best proposal for them. This concept will be a basic design proposal without the detailed drawings which will be drawn up in cooperation with the winning shipyard.
One recent example of this process was when KiwiRail’s ferry subsidiary Interislander solicited submissions to replace their existing vessels with brand-new tonnage in August 2019 for their Inter-island Resilient Connection (iReX) Project. The proposal selected at the end of this process was from OSK-Shiptech and Hyundai Mipo Dockyard (HMD), but other concepts were also considered. Sweden-based Stena RoRo was one of the other parties to submit concept proposals. These concepts were based on Stena’s proven E-Flexer design. We will look at one of these proposals further in this article.
The winning bid
During December 2020, Interislander signed a letter of intent with Danish company OSK-Shiptech and Hyundai Mipo Dockyard (HMD) of South Korea to build two ships for its fleet replacement strategy. In June 2021, the final contract was signed. While the concept design was by OSK, Hyundai Mipo is looking after both the detailed design and construction of the vessels. The two new ships will replace Interislander’s existing three smaller vessels. One of these, ARATARE, was the last vessel to be purpose-built for the company and is a rail ferry. The other two, KAITAKI and KAIARAHI, are Ro-Pax ferries acquired second-hand from Northern Europe.
The OSK/HMD proposal was for two 220m long Diesel-electric-hybrid rail enabled Ro-Pax ferries with capacity for 1,910 people, 43 rail wagons, 62 trucks, and 170 cars each. The 43 rail wagons are accommodated on deck 3, though up to 1,370lm of road vehicles (or a mix of rail and road vehicles) can be accommodated instead. Up to 1,235 lane metres of freight and passenger road vehicles can be located on deck 5. There is also a dedicated passenger car garage which stretches the length of deck 7. This is accessed via a pair of fixed ramps (one each on the port and starboard side) from deck 5. Passenger facilities are spread out over three decks: decks 8, 9, and 11.
We will be covering the winning iReX design in more detail in a future feature.
An alternative proposal
The following images and information about Stena’s Interislander E-Flexer proposal are taken from photographs of a physical brochure sent to us by one of our correspondents. As a consequence, the quality of the images may not match our usual standards.
Stena’s E-Flexer concept
Sweden-based Stena RoRo has already been successful in securing twelve firm orders for its E-Flexer design. Sister-company Stena Line, Brittany Ferries, DFDS, and Marine Atlantic all have either E-Flexer vessels in service or orders placed. The E-Flexer platform is modular in nature and was designed to be customised to the needs of operators, hence its popularity. In addition to changing the overall length of the vessel, nature of passenger facilities and the number of cabins onboard the ferry, operators are also able to select from different propulsion options such as Diesel or LNG/Diesel dual-fuel, mechanical or diesel-electric, and battery hybrid options.
By using a standard platform operators are able to keep fleet replacement costs low as economies of scale come into play. Stena RoRo is also able to take care of all project management, and shoulder the financial risks associated with shipbuilding. The Swedish company offers long-term charters for E-Flexer vessels with a purchase option, removing the need for ferry operators to raise hundreds of millions of dollars to fund a new-build programme.
The Interislander E-Flexer concept
The proposal that we will look at in this article was for a vehicle Ro-Pax ferry, though it has been reported elsewhere that Stena has also made provision for installing rails on E-Flexers to make them rail enabled.
As with other E-Flexer designs, public passenger facilities were to be located on decks 7 and 8. There would have been no separate passenger car garage, however, as is also the case on the three Brittany Ferries E-Flexers delivered to date. There was an option to add a mezzanine deck on the upper freight deck to give capacity for about 160 cars.
The passenger facilities offered would have been similar to those on other E-Flexer ferries – a passenger restaurant, cafe, two children’s play areas, truckers restaurant, a bar cafeteria, a premium lounge, and a reclined seat lounge.
However, there would have been at least two big changes – a rear facing observation lounge over decks 8 and 9 (a similar concept to that on the existing Interislander ferry KAITAKI), and a large sundeck aft on deck 7 where a car garage would be located on a Stena Line E-Flexer. This area would be cabins on a Brittany Ferries ship.
The total capacity would have been for 3,100 lm of freight (just like a standard 215m E-Flexer such as. STENA ESTRID) and about 1,900 passengers and 100 crew. With such a large passenger capacity, almost twice that of some other E-Flexer ferries, six lifeboats would have been provided rather than two.
Unlike the OSK/HMD proposal, this concept proposed by Stena RoRo would have used conventional controllable pitch propellers turned via shafts rather than the Azimuth pods used on the successful design.
Stena RoRo’s proposal would have offered two-level drive-through loading and unloading in contrast to the stern-only loading and unloading capability of OSK/HMD’s proposal.
Side by side – Interislander’s iReX and the E-Flexer alternative
| Winning iReX proposal | Interislander E-Flexer proposal | |
|---|---|---|
| Concept Design | OSK-Shiptech (Denmark) | Deltamarin (Finland) / Stena RoRo (Sweden) |
| Detail Design | Hyundai Mipo Dockyard (Korea) | Deltamarin (Finland / China) |
| Interior Design | Steen Friis Design (Denmark) / Designworks (New Zealand) | Likely Figura Arkitekter (Sweden) and local designers (New Zealand) |
| Shipyard | Hyundai Mipo Dockyard, Ulsan, South Korea | China Merchants Jinling (Weihai), Weihai, China |
| Length | 220m | 215m |
| Beam | 30.8m | 27.8m |
| Gross Tonnage | Approx. 50,000 | Unknown but likely around 42,000 or more |
| Passenger capacity | 1,910 | Approx. 1,900 |
| Vehicle capacity | 43 rail wagons plus up to 1,235lm of freight and 170 cars OrUp to 2,605lm of freight and 170 cars Or 652 passenger cars | Up to 3,100 lane metres of freight and cars. A mezzanine 2000m2 car deck could have been specified on deck 5 to allow the carriage of about 160 cars but with a reduction in freight capacity when deployed (similar to Brittany Ferries’ GALICIA, SALAMANCA, and SANTOÑA). |
| Passenger facilities | Interislander has published the following non-exhaustive list of facilities: Food and beverage choices. Premium lounge. Shops and cinema. Observation and promenade decks. Family zones. Facilities for pets. Cabins for passengers, including for people with disabilities. Commercial drivers lounges. Cabins specifically designed for commercial drivers. | Passenger restaurant. Cafe. Onboard shop. Two children’s play areas. Commercial drivers restaurant/lounge. Bar cafeteria. Gaming area. Premium lounge. Reclined seat lounge. Twin-level rear facing observation lounge. Two sundecks. A selection of passenger cabins including cabins for people with disabilities. |
