The Efficient Tugbooat: Damen Design Prove Efficient World Round

Damen is well-renowned for its innovative tug design, construction and outfitting prowess, a reputation upheld on a pair of vessels, the recently delivered Levanto Secondo and the currently under construction Damen Azimuth Stern Drive Tug 2411 yard number 512201.

Levanto Secondo

Levanto Secondo is a Damen Azimuth Stern Drive Tug 2810 delivered in October 2002, to SCAFI, an Italian operator. The design of the Azimuth Stern Drive 2810 has been completely prepared to comply with U.S. tonnage rules and USCG-requirements, so that it can be of interest and use to the U.S. market as well. Levanto Secondo is the second vessel of this type, ordered by SCAFI, and it will be used in the harbor of La Spezia in the northern part of Italy.

The ASD Tug 2810 has a round bilge hull with a transom stern and a rounded bow. The transom corners are well rounded and the forecastle gives sufficient bow height for severe working conditions. The hull is divided into five compartments and features 10 mm side and bottom plating, and 8mm deck plating. Bottom plating in the thruster area is increased to 12 mm, and the sheerstrake has a plate thickness of 15 mm. The large superstructure has ample space for a separate galley and mess room and for the cabins for the captain and the chief engineer. Below deck three cabins are arranged, two single officer's cabins and one three crew cabin. All below deck cabins are arranged above the waterline. The wheelhouse has a control stand, with an excellent optimal view in all directions.

A pair of nine-cylinder Wärtsilä 9L20 engines (1,620 kW (2,172 bhp) at 1,000 rpm each) power Levanto Secondo, driving Schottel SRP 1212 thrusters, with controllable pitch propellers. The vessel is designed to comply flexibly to a specific owners need, as it is able to accommodate a number of different engines and thrusters from different manufacturers.

On the fore deck and on the aft deck Kraaijeveld towing winches are fitted. The brake holding power of both winches is 130 tons, and both winches have stainless steel rims with band brakes and friction clutches. The fore winch is of the single drum type, suitable for 150 m synthetic rope of 80 mm diameter. The pull of the fore winch is 10 tons at 20 m/min., or 20 tons at 10 m/min. The aft winch can store 200 m synthetic rope of 80 mm diameter and has a pull and speed of 10 tons at 20 m/min or 20 tons at 10 m/min. The ropes used on the fore and aft winch run through stainless steel triangular fairleads integrated in the towing bitt.

On the aft deck a Kraaijeveld capstan of 3.5 ton pull is arranged, and a Mampaey towing hook of 65 ton Safe Working Load is fitted.

Azimuth Stern Drive Tug 2411

The Damen Azimuth Stern Drive Tug 2411 (yard number 512201) is currently being built in China and is expected to be ready for delivery in October 2003. The ASD 2411 is the newest product of the Damen ASD series and is a typical harbor tug with designed to provide excellent maneuverability and impressive bollard pull. The vessel's hull shape and appendages were finalized after a successful series of model tests at the MARIN test basin facilities in The Netherlands. It, too, complies with the stability criteria of U.S. Coast Guard. The classification society for this vessel is Lloyd's Register of Shipping. Two sixteen-cylinder Caterpillar 3516B TA HD engines power the ASD 2411. The output of each main engine is 4,170 kW (5,592 bhp) at 1,600 rpm. These engines drive the Aquamaster US 255 thrusters, with fixed pitch propellers. Between the main engines and the thrusters, slipping clutches are fitted, make Twin Disc, type MCD-LD. By means of these slipping clutches, the propeller speed can be controlled very accurately when main engines run at idle rpm. The thrusters have a propeller diameter of 2600 mm. The nozzles are with stainless steel inner ring.

The ASD 2411 is fitted with two Caterpillar auxiliary engines, driving 106 kVA Caterpillar SR4 generators. The ASD Tug 2411 is equipped with a SIHI fire-fighting pump of 600 m3/hr at 10 bar, driven by a Caterpillar 3306B engine.

In front of the deckhouse a manually controlled Ajax fire-fighting monitor is fitted, with a capacity of 600 cu. m./hr. A venturi type foam-mixer is installed at the pump, up to a maximum of six percent. Furthermore, an electrically submersible driven salvage pump is delivered.