Ice-breaking tug designs unveiled

ILS Ship Design & Engineering has introduced a new series of design concepts for harbour, escort and offshore tugs with ice-class hulls. Its Knight series includes an azimuth stern drive (ASD) harbour tug with ice-breaking capabilities and an Arctic-class dual-fuel, escort tug for year-round operations in terminals and coastal waters. 

ILS also designed an ice-breaking escort and oil-spill response tug and multipurpose offshore support vessels and anchor handlers for various markets. 

“We are launching a series of tug, workboat and offshore support vessel concepts, Knight design series, all with the traditional ILS design philosophies behind them,” says ILS Ship Design & Engineering chief executive Kristian Lehtonen. 

Based on vessels ILS previously designed, they were built by shipyards for the most extreme Arctic environments and ice conditions encountered in the Baltic, Gulf of Bothnia, Gulf of Finland and the Sakhalin Sea area. 

Designed for vessels built for ice breaking, ship handling, harbour operations, coastal towage, ship escort and emergency response throughout northern Europe, Asia and in North America, when these designs are selected for a newbuild, ILS will complete the conceptual and basic design, and carry out full-scale ice and escort trials. 

The ILS Knight ASD harbour icebreaker and escort tug is based on the design for Ahto, which is working at the northernmost Finnish harbours Kemi and Tornio, with class notations for a tug with unrestricted navigation to Ice 1A Super and automation for unmanned machinery spaces.  

This vessel is capable of escort towing and ship berthing, ice breaking and management, oil spill response and general towage, with an overall length of around 40 m, moulded beam of 13 m, moulded depth of 6 m and draught of around 5 m. With a bollard pull of 43 tonnes and speed of 12 knots, it can break 90 cm of ice at 2 knots, from total propulsion power of 3,600 kW. 

Ahto achieves this with two Wärtsilä 9L20 main diesel engines, each developing 1,800 kW at 1,000 rpm, driving two Kongsberg US 305 azimuth thrusters with controllable-pitch propellers. It has a Kongsberg TWH 1500/100 towing winch, Melcal deck crane with capacity of 6 tonnes at 16 m and a Kongsberg ETWH anchor windlass and escort winch. It has capacity for 150 m³ of fuel oil, 150 m³ of ballast and 16 m³ of fresh water. 

Another Knight ASD harbour icebreaker and escort tug design is based on the tugboat Vityaz, which is operating at the De-Kastri oil export terminal near Sakhalin Island, with class notations for ship escort, Ice 1A Super, and oil recovery. 

This 52-m vessel is designed for escort towing, ice breaking and management, anchor handling, oil spill recovery, fire-fighting and coastal towage. With a moulded beam of 14 m, depth of around 7 m and under-keel draught of 5 m, it has accommodation for 12 people. Vityaz has twin Wärtsilä W6L26C main engines, each developing 2,040 kW of power and driving two Kongsberg US 305 P40 azimuth thrusters with controllable-pitch propellers, a Kongsberg bow thruster with 350 kW of power and Cummins K-19 DM generators. 

ILS has also designed a Knight Arctic-class escort tug suitable for harbour ice breaking and management and year-round towing, search and rescue operations, fire-fighting and anchor handling. 

This 52-m, 447-gt tug will be classed to Polar Code 5 with FiFi1 fire-fighting and automation and ship-escort equipment. With a moulded beam of 14 m, moulded depth of around 8 m and under-keel draught of 6 m, it has total power of 8,600 kW.  

Dual-fuel main engines and generators drive ABB Azipod azimuth thrusters and one electric-driven Kongsberg bow thruster. This escort tug will have transit speed of 14 knots and could break 1 m of ice.