Isle of Man flag for NZ Interislander ferries

KiwiRail has commissioned the two future-proofed vessels to modernise its Interislander service which connects New Zealand’s State Highway and national rail networks between Wellington in the North Island and Picton in the South Island via the Cook Strait, carrying approximately 850,000 passengers, 250,000 cars and up to NZ$14Bn (US$9.8Bn) worth of freight annually.

The Isle of Man Ship Registry will serve as the newbuilding Flag, working in partnership with KiwiRail’s chosen classification society, and overseeing the build process once a shipyard has been confirmed.

Denmark’s OSK-ShipTech will design the two 220-m diesel-electric hybrid power ropax ferries capable of carrying 1,900 passengers each. Diesel generators and batteries will provide electrical power for azimuth thruster propulsion.

KiwiRail said it is focused on maximising efficiency and incorporating environmental features to minimise CO₂ emissions. This includes making the ferries adaptable to new fuel sources as they become available. The vessels will also have a capacity of approximately 3,600 lane metres allowing them to transport a combination of vehicles including up to 40 18-m rail wagons.

A senior surveyor at the Isle of Man Ship Registry, Chris Martin said “As these two sister vessels will be carrying passengers, cars, freight and rolling stock, they will be quite flexible in their capabilities. They will need to be able to turn around in 60 minutes at peak times, so will have a dual-capability linkspan to allow rail freight and vehicles to load and unload at the same time.

“The ferries will also have to comply with quite stringent wave energy rules required for speeds in excess of 15 knots in the Marlborough Sounds, at the northern end of the South Island. This will require a very efficient hull form that must also have excellent seakeeping properties to deal with the often-challenging sea conditions experienced in this area of the world.”

In addition, the Wellington and Waitohi Picton waterfronts will now include new ferry berths, terminals and both rail and road connections to ensure the benefits of the new ferries are fully realised.

KiwiRail Interislander general manager Walter Rushbrook said “It is over 20 years since New Zealand introduced a brand-new purpose-built ferry to its fleet, and we expect the new ferries will provide another 30 years’ service. Future-proofing the vessels so they can become even more efficient in future is important to us, as our goal is to reduce KiwiRail’s carbon emissions by 30% by 2030 and become carbon neutral by 2050. We estimate that from day one the new ferries will reduce the Interislander’s emissions by 40%.”

The ships are targeted to enter service in the mid-2020s, replacing the existing three-vessel Interislander fleet.