N.P. Grabdredge

One of a series of six grab dredges recently constructed, this unit is designed for versatility and in addition to its prime function as a dredge it can be operated as a floating crane and piling rig. The rectangular pontoon hull is of all welded construction and built under special survey to the requirements of Germanischer Lloyd’s Register class 100 A51 Floating Crane, ‘Extended Protected Waters Service’.

The lower deck comprises five ballast tanks for equalisation of the trim during crane  operations, fully ventilated engine room: three buoyancy compartments, Fuel Oil and Fresh Water tanks and two main fitted storerooms with secondary storerooms in the wing compartments.

The crew of 9 (One foreman and 8 operators) are accommodated in one single and four double berths and are provided with a fully fitted galley/messroom with seating for ten and a colour television. Adjacent are an office and toilet facilities comprising a washroom with basin, showers, and toilets. The complete accommodation is fully fitted and ventilated. Constant contact with the shore and other vessels is maintained by VHF radio telephone.

Ancillary equipment supplied with the vessel includes full lifesaving and firefighting equipment, a complete electric welding plant for maintenance purposes and a fiberglasswozrkboat davit mounted and operated by an electric winch. Deck winches, capstans and rope reels are mounted outboard on the pontoon leaving maximum clear space for working and for handling storage of pile driving equipment. Power for all auxiliary machinery is supplied by Lister type JW6MA Marine Diesel engine developing 138 h.p. at 1800 r.p.m. driving an 80 kW Marine Alternator.

Dredging Machinery

Mounted on the pontoon is a totally self-contained crane unit mounted on a special seating incorporated in the main structure of the pontoon. The unit can rotate through 360° and is fitted with a standard boom of 15 metres length with extension pieces to allow a maximum boom length of 35 metres.

The unit may be employed in 3 distinct and separate ways:

1. As a Grab Dredge, using boom length of 15 metres. In this mode, grab buckets of 3.0 m³ (2 element type) are used, or alternatively 2,5 m³ orange peel grabs for dredging large underwater obstructions, rocks, etc.
2. As a floating crane, when the maximum boom length of 35 metres may be employed. Crane hooks for handling loads of 12.5 tonnes, 40 tonnes, and 50 tonnes are supplied. 
3. As a pile driver, when pile driving leaders and hammers are fitted to the crane unit.

Main Alternator:

Lister Diesel type JW6MA developing B8 H.P. @ 1800 RPM driving in 80 KW Alternator.

Grab Crane:

Weserhutte type W.320 fitted for 

A) Dredging Duties

B) Crane Duties

C) Piling Duties

The vessel is of fully welded steel construction suitable for harbour and coastal service. The vessel complies with, and was built to achieve Germanischer Lloyd Classification Society notation: “100 A51 Floating Crane”