VESSEL REVIEW | Truck-transportable tug for barge handling and ship assist duties
The first example in a new series of compact, truck-transportable tugs has been handed over to the US Army Corps of Engineers (USACE).
The tug was built by Silverback Marine of Tacoma, Washington, to a design by Seattle-based naval architecture firm the Elliott Bay Design Group (EBDG).
The vessel has a length of only 25 feet (7.6 metres), a beam of 16 feet (4.9 metres), a draught of only 40 inches (one metre), and space for up to four crewmembers.
Compact platform offering versatility typical of larger vessels
Two Qummins QSL9 diesel engines power two Schottel SRP 100 216kW compact Z-drives housing 850mm propellers to deliver enhanced manoeuvrability, a bollard pull of approximately 7.2 tons, a top speed of 12 knots, and an average range of 150 nautical miles.
EBDG said the concept was designed to fulfil the vision of a truly tow-capable, tractor tug-style vessel for use by operators in the non-US Coast Guard Subchapter M market. Traditional truck-transportable tugs, driven by propellers and rudders, are suited strictly for pushing, with limited manoeuvrability.
Silverback remarked that the tug’s bollard pull, coupled with its compact size, will help operators avoid costly Subchapter M requirements while providing a more economical alternative to larger tugs. The company’s founder Ian Gracey said that, because of their manoeuvrability, two compact tugs of this design can take on the workload of one larger tug.
The deck equipment includes a 480V three-phase towing winch and two line handling winches all supplied by Wintech. The wheelhouse provides 360-degree visibility as well as upward-facing windows, thus significantly enhancing the helm operator's situational awareness.
Modular construction permitting flexibility in deployment
The wheelhouse itself is removable, allowing the tug to be easily dismantled, transported to a work site, and then reassembled on-site.
The helm operator sits on a NorSap seat. Additional seats are also available in the wheelhouse for up to two other crewmembers. The electronics include a Furuno radar.
The engines are fed by a 400-gallon (1,500-litre) tank while power for the onboard systems is supplied by a 30kW generator. The other key equipment includes a tow bitt, bollards, chocks, and push knees.
Secondary training function
The tug may also be used as a training platform to help familiarise crews with operation of vessels with azimuthing thrusters.
The new tug handed over to the USACE will be used primarily for barge handling and ship assist duties.
Silverback said the hulls of later tugs in the series can be built in either steel or aluminium and that each vessel can be tailored to better satisfy operator requirements.
