THIS strange-looking craft is one of the many types of dredger used for keeping ship channels open. She is non-self-propelling and has no hoppers within her hull into which the dredge spoil can be discharged. Instead it is sent over the side down chutes as the drawing above indicates.
She is steam-operated and is known technically as a non-self-propelling bow well bucket dredger. She consists mainly of a boss-shaped hull, with a long oblong slot cut in the forward end. In this the dredge arm, with its endless belt of buckets, moves up and down in a vertical direction, the maximum dredging depth being 75 feet. The heavy dredge arm - generally called the “ladder” - is hinged at a store slightly abaft amidships and is raised or lowered by special crane gear built over the bow well.
The buckets on their belt derive their motion from a reciprocating engine, which is placed amidships in the hull and operates a wheel by chains; the wheel in turn meshes with the wheel operating the buckets. The boiler supplying steam to the reciprocating engine is situated abaft the engine itself.
Quarters for the crew are somewhat limited and are arranged in the hull abaft the bow well. This ungainly vessel has to be towed to and from her duty, but when in position can move herself in a fore-and-aft or sideways direction by means of winches on the deck attached to long cables securely fastened to the sea or river bottom by anchors.
The vessel has an overall length of 200 feet; the pontoon rate, as the hull is called, is 180 feet between perpendiculars. The moulded breadth is 34 ft 10 in, and the depth of hull 12 feet. The normal dredging depth is 60 feet; with an auxiliary ladder the full depth of 75 feet is reached.