SAAM Towage Canada’s electric twins go to work in Vancouver

SAAM Volta [Photo: Sanmar Shipyards]

Now in service with SAAM Towage Canada, the SAAM Volta and Chief Dan George are the first battery electric tugs built specifically to operate in Vancouver, B.C. Built to Robert Allan Ltd’s ElectRA 2300-SX design by Turkey’s Sanmar Shipyards, the tugs mark a milestone in the Port of Vancouver’s goal of becoming the world’s most sustainable port as well as SAAM Towage’s leadership in the drive to the decarbonization of harbour operations.

Optimized for emissions-free ship-docking operations in their home port, the tugs’ compact 23 meter lengths and outstanding maneuverability make them well suited for operations between the tight “finger piers” where many ships are docked in Vancouver. They are also ideal for ship-berthing and unberthing work at Neptune terminals in Vancouver where their environmental credentials were instrumental in winning them a contract to provide towage services.

The vessels’ maneuverability is a product of a concerted effort during the design to give them handling characteristics tuned to the preferences of SAAM Towage Canada’s crews. After surveying SAAM’s local tug masters, Robert Allan Ltd. embarked on a series of live trials to quantify handling characteristics that these captains identified as most favourable. Using a specialized sensor package, and by closely listening to what the tug masters said they could feel, it was possible to establish a quantified baseline for what the new design should ideally achieve.

Predictions of the performance of the new tugs were made using a proprietary CFD-based manoeuvring tool which was validated using the earlier trials. Using this tool, it was possible to establish that the new design, for which underwater features were customized to suit the desired performance, should indeed deliver the specific characteristics that SAAM Towage Canada’s crews had identified as being optimal. The tool was also used to check that directional stability would be on par with expectations. A key feature of the hull design is a relatively minimalistic and strategically shaped single skeg that has low drag in all directions, and the benefit of reduced energy consumption in transit.

Sea trials showed that handling, performance, and maneuvering characteristics were exactly what had been hoped for. This was demonstrated when SAAM ordered a new 25-meter ElectRA 2500-SX design from Sanmar to operate in Chile and specified that the existing 25 meter design be updated to have a geometrically similar underwater hull and appendages to the 23 meter tugs.

The two tugs feature a 3,616 kWh lithium-ion battery installation, split between two battery rooms, that sets a new standard for the total capacity that can be installed in a compact tug. The high capacity enables the relatively high-usage harbor tugs to perform their missions on battery power alone. With charging from the local hydroelectric power grid in as little as one to two hours, the tugs can quickly get out to the next job and accommodate a busy schedule.

Each of the two new SAAM Towage Canada tugs is expected to reduce emissions by over 1,200 tonnes of CO2 per year from tank-to-wake (and even more from well-to-wake) compared to diesel counterparts. Emissions of NOX, SOX, CO, and particulate matter will all be zero as well when operating on their generous battery banks. The reductions for the tug pair are on par with removing over 600 cars off the road.

Impressive as these tugs’ maximum performances may be, they also perform their missions with exceptional finesse, says Robert Allan Ltd. The electrical propulsion system affords fine control of thrust including at very low speeds. This affords the master additional control in feathering up against an assisted ship, with soft contact ensured by an extended cylindrical fendering system that keeps pressures below 20 tonnes per square meter, even when applying the full bollard pull of 70 tonnes.