TUGS & SALVAGE

New Escort Tug Under Construction for Norwegian Owners

23 years ago

Norwegian tug owners Bukser og Berging AS have entrusted Moen Slip A/S of Kolvereid, with the construction of the new state of the art escort tug. One of the worlds most advanced vessels of its kind, the new tug will serve the Statoil Mongstad Oil Terminal and replace the escort tug Bob that will then be released for use elsewhere. Escort towage is an essential element in measures taken by Statoil at Mongstad to prevent tanker related accidents and possible oil pollution in the relatively narrow Fensfjord.

A new escort tug for B&B will have the latest Voith propellers.

The new vessel is a larger and more powerful version of the ‘fin first’ tractor tug Boxer that entered service at Mongstad in 1999. In keeping with earlier escort tractors designed by Bukser og Berging’s own naval architect, the hull and skeg will have similar highly developed underwater characteristics intended to generate maximum steering forces whilst operating in the ‘indirect towing’ mode at relatively high speeds. When meeting ships arriving from sea, the new tug will be able to make fast towline at speeds of up to 14 knots.

Moen Slip has built a number of technologically advanced escort tugs for the same owners in the past decade and delivery is scheduled to December 2003.

The new vessel will measure 40.5m in length, have a beam of 14.30m and moulded depth of 5.14m. When completed the tug will have a static bollard pull of 95 tonnes and produce a steering force of 160 tonnes in the indirect towing mode at 10 knots.

Running free at full escorting draft the vessel will have a top speed of 16 knots.

Two Deutz SBV 16 M 628 main engines producing a total of 9348bhp will power a pair of Voith Schneider 36R6/255-2 cycloidal propulsion units of the very latest type. These units are a recent development of the well-tried Voith propeller that now incorporates six blades of a new profile and length.

These will be fitted in conjunction with an improved ‘nozzle and protection plate’ expected to provide a significant improvement in bollard pull per unit horsepower.

Special attention has been paid to the towing gear. The winch, manufactured by Karmoy Winch AS, will have a single, hydraulically powered, drum with a maximum line pull of 175 tonnes and brake holding load of 300 tonnes. Sophisticated, programmable, winch controls will incorporate a tension and compensation system, capable of maintaining preset towline lengths and forces. For escort duties a high-tech Dyneema towline will be used, with a length of 180m and 82mm in diameter and a maximum breaking strain of 450 tonnes.

In common with all escort tugs at the Statoil Mongstad terminal and in the Bukser og Berging’s fleet, the new vessel will be subjected to full-scale trials by Det Norske Veritas (DNV) in order to achieve an approved escort tug notation. When completed the vessel will carry the classification: – DNV +1A1, ice C, EO, tug, SF, FiFi I, oilrec, escort (160, 10).