Maritime Propulsion

Sanmar’s first VSP (Voith Schneider Propeller) tug, of the new VectRA 3000 series, named Arie A has been constructed for Italian operator Tripmare Spa of Trieste. The vessel has been delivered by a Redwise crew to Ashdod Port, located some 40 kilometers south of Tel Aviv where it will operate. 

 

Particular care and attention has been given to the ergonomics of the wheelhouse and the habitability of the crew accommodation, the builder said.

 

VectRA 3000 series has been designed by the Canadian naval architects Robert Allan Ltd. This design, developed exclusively for Sanmar, contains many innovative ideas from both the builder and designer aimed at developing a cost-effective VSP tug for the world market. Sanmar’s brief to Robert Allan Ltd was to create a VSP tug which was under 500 GRT and which would incorporate high-speed engines, a clutch between thruster and engine,  electronic controls and be fully MLC 2006 compliant for all crew accommodation. The challenges therefore focused on the machinery design and the overall layout. 

 

The tug measures 30.25m in length with a molded beam of 13m and an overall draft of 6m, but its most unique aspect is the propulsion arrangement. Driving the forward located Voith type 32-R5 250 cycloid propellers are a pair of Caterpillar 3516C high speed diesels, each developing 2525kW at 1,800rpm. Instead of the traditional Voith Turbo coupling, the engines are connected to the Voith propulsion through a pair of Reintjes model WAF 843 clutch and reduction gearboxes. This reduces transmission losses, thus increasing the overall propulsion efficiency, and also enables the drives to be de-clutched at idle, significantly reducing fuel burn. Using high-speed engines also significantly reduces the space occupied by drive machinery and of course results in much lower weight, allowing a finer more efficient hull form for the same deadweight.

 

The installed cost is also significantly reduced. This machinery combination will deliver a bollard pull of up to 70 metric tons and will drive the hull at a predicted speed of not less than 12.5 knots.

 

This tug also incorporates the new electronic Voith Remote Control system. It is set up to work in combinator mode whereby both rev/min and pitch increase together at a predefined ‘ramp up’. It is believed that this is the first installation of high speed engines with VSP drives in conjunction with the Voith Electronic Control System. Just like ASD tugs, this combination allows the captain to clutch-off the thrusters when the tug stays at idle and hence save fuel.

 

The Voith and Engine Control panels are located on consoles with motorized controlled tilt facility and the towing winch control panel is located on the console with removable system to vary the position of this panel. The control panel can be removed from one space to another by a sliding mechanism for easy and ergonomic use of the captain or chief engineer. 

 

The radar/ECDIS screens have height adjustable motorized lifting columns with fully adjustable monitor mounting kits. 

 

Voith tractor tugs have high power requirements for their size. As in most vessels of this type, crew spaces are located over the critical noise and vibration producing machinery - the propulsion diesels and genertator sets. However, peculiar to tractor tugs, the Voith Schneider propellers are located just forward of amidships rather than aft, which places them directly below the crew's quarters. 

 

Arie A has Crew Habitability on Workboats ( HAB(WB) ) notation from ABS , all noise, sound, vibration and lighting are appropriate for classification requirements, such as less than 60 db(A) sound level and 5 mm/s vibration level  in all cabins at 12 knot cruise speed, with using special high-tech insulation materials on deck and bulkheads and special resilient mounts and elastic couplings for propulsor and paneling installation. 

 

The flush deck layout is relatively conventional for a Voith Tractor, but in compliance with Maritime Labor Convention 2006, all accommodation is on the main deck, with two single cabins for officers, two single cabins for petty officers and one double cabin for crew, each with private en-suite facilities. The galley and mess area adjacent to a central entry and wet lobby area complete the outfit. 

 

The vessel is equipped with a DMT TW-H 800kN hydraulic driven double drum winch with tension indication. The winch is also provided with hydraulic operated friction clutches. First drum has the capacity of 710m Ø 54mm steel cable at 10 layers whereas the second drum has the capacity of 150m Ø94mm nylon rope at 6 layers. Both drums have a brake capacity of 200 tons.