Yasin - Trailing Suction Hopper Dredger
The Yasin is a Suction Hopper dredger, with a secondary use as a vessel designed to combat oil pollution. It was built at IHC Holland's Kinderdijk yard in the Netherlands, for the Ports and Shipping Organisation in Iran.
The Yasin has an overall length of 70.3m or 63m between perpendiculars. It has a 14m beam, a 4.8m depth and a 4m draught. It is a single deck layout with the accommodation facilities located in fore, on a raised quarter deck.
The dredging system is based on a hopper with a capacity of 1,000m³ which gives the vessel a loading capacity of 1,425t. This has a telescopic overflow duct, which is adjustable to afford optimal settling of the spoil. There are four hydraulically-operated bottom doors, operated from the wheelhouse, which can immediately discharge the contents.
The dredging is carried out by means of an IHC-designed double walled centrifugal pump system. The ship has a dredging depth of 8m and the trailing suction pipe diameter is 0.5m.
A trunion elbow, vertical hinge and turning gland allow the draghead to remain on the bed while still giving full vacuum. The drag head is suitable for materials, ranging from compacted soils to silt. Water is supplied to the head by means of a pair of 1,480rpm pumps with a capacity of 700m³/hr. The dredging information equipment, supplied by IHC Systems, monitors the suction tube position, dredge track, draught, loading and production in general. This gives the operator useful data about the amount of dredging work, performance details and the state of the bed after the dredge. There are also sensors located on the hull which give the operator fore and aft draught while taking into account the specific gravity of the water.
A horizontal hydraulically-driven windlass is located on the forecastle deck. Driven by a main motor via a totally enclosed gearbox, it gives the cable-lifters a hauling speed of 10m/min. It is suitable to pull up to 20kN.
For mooring, there are two stockless bow anchors, each weighing 1,300kg.
The crane was supplied by Technisch Bureau Uittenbogaart.
ACCOMMODATION, COMMUNICATIONS AND LIFE-SAVING
Accommodation for 13 people and one guest is arranged in a deckhouse above the main deck on the foreship. Nearby, in the bridge, the navaids and comms package was provided by Radio Holland. It comprises a magnetic compass, gyrocompass, rudder position indication system, autopilot, echosounder, speed log and two radar. There is also a Navtex receiver, radar transponders and two Inmarsat C systems.
An inflatable motor rescue boat with a 10W outboard motor is part of the life-saving equipment. There are also four self-inflating life rafts life buoys and immersion suits. The Maxi-Guard alarm and monitoring system was provided by Praxis Automation.
PROPULSION, POWER AND MANOEUVRING
The engines consist of a pair of turbocharged Deutz diesel units, which produces a rotary speed of 1,500rpm at a power of 800kW. Each is linked to an Ads van Stigt reverse reduction gearbox, and from there to a fixed pitch propeller. There is also a Deutz auxiliary engine, working at 1,500rpm at 250kW, principally for the jet pumps. For manoeuvring, there is an electrically-driven bow thruster. This 1m-diameter propeller rotates at a speed of 495rpm.
The steering gear is electro-hydraulically driven. The Yasin uses twin free-hanging rudders linked by a heavy rod.
The power system consists of three diesel gensets, each comprising a 250kW Deutz diesel engine and an AC generator with an output of 232kW at 1,500rpm. These are semi-automatically synchronised to run in parallel. There is also a Deutz emergency generator with an output of 96kW at 1,500rpm.
The Yasin is registered by Lloyds under the notation +100A1, Hopper Dredger, XLMC, Unrestricted navigation, Caspian Sea Service.