VESSEL REVIEW | Spartan – Hybrid escort tug enters service with US operator Seabulk

Master Boat Builders of Alabama recently delivered a new hybrid electric ASD escort tug to Florida-based the Seabulk Group for operation by its Seabulk Towing Services business unit. Named Spartan, the Robert Allan Ltd (RAL) designed newbuild is the first in a series of two tugs that are built to meet US Coast Guard regulations and classed through the American Bureau of Shipping (ABS), including escort notation.

The all-steel tug has an LOA of 98 feet (29.87 metres), a beam of 43 feet (13.1 metres), a design draught of 18.5 feet (5.64 metres), and a gross tonnage of 297. An integrated hybrid electric propulsion system includes two US EPA Tier IV Caterpillar 3512E main diesel engines that each produce 2,550 hp (1,901 kW) at 1,800 rpm, two Berg Propulsion MTA 628 fixed-pitch propellers, and two ABB propulsion motors and associated Berg variable frequency drives.

Auxiliary power is available in the form of Caterpillar generators – two C18 565kW sets and a C7.1 200kW unit – that also supply power for an electronics suite that includes two radars and a compass from JRC, an autopilot and pilothouse consoles from Alphatron, and a Furuno depth sounder.

Besides being capable of delivering a bollard pull of 90 tons (81 tonnes) and a speed of 12.6 knots, the hybrid propulsion ensures high levels of redundancy and allows the tug’s crew to easily switch among various operating modes – main engines only, generators only, or both to optimise fuel consumption – when needed. To help reduce wear on the engines, the tug can sail under its own power using just one generator.

The deck equipment include a forward hawser winch and a hydraulic capstan on the stern as part of a Jonrie Intertech package.

The tug is also equipped with two 10-person liferafts from Viking Life-Saving Equipment. The crews are housed in four staterooms with a total of eight berths. Four toilets are also fitted.

Homeported at Port Everglades in Florida, Spartan – as well as its yet unnamed sister vessel – will operate alongside two earlier RAL-designed tugs in the Seabulk towage fleet. The new tugs represent Seabulk’s initial investment in hybrid-powered towing assets and will operate as part of the company’s existing harbour support vessels in the Gulf of Mexico and the US East Coast. RAL said that the design for these tugs also includes arrangements that will allow for the future installation of batteries to help further reduce emissions.

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