The fitting of fire-fighting capacity on harbour tugs is very common, but typically those installations are limited to up to the capacity of the classification society Fi-Fi 1 designations with a total pump capacity of 2,400m3/hour.
Kuwait Fire Services required a major terminal support tug with significant towing and ship-handling capabilities, as well as a Fi-Fi II capability of 8,400m3/hour, however, and turned to Canadian designer Robert Allan to develop a new design.
The result is 'Mojaweb', the first RAstar 3900-class fire-fighting tug, which was built by Simulation Tech of South Korea.
The new vessel was delivered in early March 2011, and is currently sailing under its own power from Korea to its new home in the Port of Shuwaikh, Kuwait.
Features
The hull form incorporates a significant outward flare (or sponson) on the upper hull sides. When the tug is heeled over under influence of the towline during an escort operation, the sponson is submerged and a large righting force is generated to improve the stability, thus increasing the available towline force.
In addition, the hull has a large extended skeg, also designed to provide increased roll-damping. This design approach is an alternative to simply making a tug "fatter" on the waterline, and results in better fuel economy.
The RAstar hull form also provides reductions in roll amplitude and roll accelerations compared to old-style, wall-sided tug hull forms, and thus provides a safer and more comfortable platform for the crew.
'Mojaweb', although equipped primarily as a fireboat, is also equipped for typical tanker support and ship-handling work, with a hawser winch on the fore deck, and a 75-tonne SWL towhook aft. The accommodation is arranged for an operating crew of up to 14 persons, with a berthed crew of nine, but it also has the capability to accommodate survivors and/or additional fire fighters.
The wheelhouse is designed to provide maximum all-round visibility from a single split type master console forward, and a fire-fighting console aft.
The propulsion machinery consists of a pair of Wärtsilä 6L26 medium-speed diesel engines, each rated 1,946kW at 1,000RPM. These each drive a Wärtsilä-Lips CS250-CP Z-drive unit, with a 2,400mm diameter propeller. The Fi-Fi II fire-fighting capability is provided by a centre independent pump engine, Wärtsilä 8L26 diesel, rated 2,590kW at 1,000RPM, driving two pumps, each rated at 2,400m3 per hour, and a pair of 1,800m3 per hour main engine-driven pumps.
