Robert Allan Ltd. TundRA Designs

Robert Allan Ltd. has decades of experience in designing ice-capable vessels including tugs. The TundRA series was developed as a compact icebreaker capable of continually breaking ice with a thickness of up to 1-1.2 metre at a speed up to 3 knots. The hull structure is designed to meet Finnish-Swedish (FS) Ice Class Rules to ensure safety during icebreaking operations.

Each TundRA is also customised to meet the end-user requirements. Although the emphasis of the design is based on ice-class requirements these tugs are a multi-functional tool, combining good open water performance with effective icebreaking capability as well as being capable of providing significant escort performance.

Typical tasks for a TundRA tug include ice breaking and ice management, channel clearing, ship assist in ice as well as escort service, coastal towing, navigation aids service, firefighting service, limited cargo transfer and other capabilities in extreme climate conditions. The wheelhouse and deckhouse are designed for optimum all-round visibility.

These tugs break ice with their acceleration, weight, hull shape and power. The well proven spoon-shape bow, and round bilge hull form is developed based on extensive model testing. This hull shape merges into a modern ship-docking style bow, providing low fender contact pressures for ship handling duties.

Ice-knives are added under the stern to prevent large blocks of ice hitting the propulsion units when going astern or turning around in the channel. The hull shape combined with dual z-drive configuration allows for dynamic clearing of a channel to a width of twice the tugs beam.

Some of the additional design features include the covered winch on the foredeck and heated working-decks and other winterization elements.

The propulsion options vary between a single screw, open wheel TundRA 1900 to z-drives with controllable pitch propellers in nozzles as on TundRA 3600. Bollard pull performance vary between 6 and 100 MT respectively.

The design is optimised for the most onerous ice performance criteria. This results in slightly less efficient open water performance, but this can be minimised by using the modern diesel mechanical-electrical hybrid power configuration designed to match the intended operational profile. The hybrid configuration results in a significant reduction in carbon emission as well as flexibility in the operational modes. This, in turn, leads to less maintenance cost, fuel savings and minimal environmental impact.

The TundRA series of ice-class tugs are denoted by length. For example: TundRA 1900 (19 m LOA).