VESSEL REVIEW | SD Aisemaht & SD Qwiy Aanitsa Sarah – Kotug Canada places methanol-powered escort tugs into service

Kotug Canada, the partnership formed by Dutch towage specialist Kotug International and Canada’s Horizon Maritime. recently unveiled what it said are the world’s first large, purpose-built dual-fuel methanol-powered escort tugs.

Designed by local naval architecture firm Robert Allan Ltd (RAL), SD Aisemaht and SD Qwiy Aanitsa Sarah each have an LOA of 43.8 metres (144 feet), a beam of 15 metres (49 feet), a minimum draught of 6.3 metres (21 feet) and a bollard pull of between 115 and 120 tonnes, placing them among the most powerful escort tugs operating in Canada.

Rather than retrofitting existing tonnage, Kotug chose to invest in purpose-built vessels optimised from the outset for performance, safety and sustainability.

Flexible dual-fuel propulsion

The RAL-designed tugs are equipped with Anglo Belgian Corporation 16V DZM dual-fuel engines capable of operating on diesel or methanol, enabling substantial reductions in CO₂ emissions when supplied with renewable methanol. Fully compliant with IMO Tier III standards, the propulsion system on each tug integrates advanced emission control technologies, shaft alternators, and optimised energy management systems.

The engines on each tug drive two Schottel SRP 710 rudder propellers to deliver a free running speed of 14 knots. Schottel also supplied each tug’s STT 170 side thruster.

A mechanical cross-link system will enable one engine to power both azimuthing thrusters during transit operations. Kotug said this will reduce fuel consumption, lower engine running hours and improve overall efficiency, particularly during low-load sailing. According to the owner, the result is a smarter energy profile and reduced environmental footprint without compromising operational readiness.

In addition, advanced hull coating solutions help minimise underwater radiated noise, contributing to the protection of sensitive marine ecosystems along Canada’s West Coast, including whale habitats.

Also outfitted for firefighting and oil spill response

The tugs are equipped with firefighting equipment meeting the requirements of American Bureau of Shipping’s (ABS) FFV 1 notation and will have the largest spill response capabilities of any tugs on the British Columbia coast to mitigate the risk of marine spills to the Salish Sea and communities from laden tankers as well as other commercial marine traffic.

High quality onboard equipment will include heavy duty electric winches fit fore and aft for reduced noise and to significantly reduce the risk of a hydraulic oil spill into the environment. The forward escort system on each tug has been customised to suit the requirements of local pilots.

RAL said the aft towing system with a dual drum winch with steel wire is among the largest fit to an escort tug and combined with the vessels’ exceptional manoeuvrability, it provides the capability to perform emergency towage of vessels that may find themselves in distress along the route.

Inside each tug, the accommodation includes spacious dedicated cabins and en suite toilets for all regular crew, all with natural light, and well in excess of regulatory standards. To facilitate training and additional response capability, extra berths will be provided for use by Western Canada Marine Response Corporation spill response technicians.

Particular attention has been paid to minimise noise and vibration aboard the vessels, with a crew comfort (habitability) class notation to be assigned by ABS along with the ENVIRO and SUSTAIN notations indicating reduced environmental impact.

SD Aisemaht and SD Qwiy Aanitsa Sarah will service the Trans Mountain Expansion Project that runs from Edmonton, Alberta, to the Westridge Marine Terminal in Burnaby, BC. In particular, the tugs will escort tankers from the harbour limits of the Port of Vancouver to the open Pacific Ocean through the commercial shipping lanes of the Salish Sea.