SEA-GOING LADDER DREDGES 77 



to have at its disposition a dredging machine sufficiently powerful 

 to maintain the navigable channel open at all times. 



This machine has recently been delivered by the constructors 

 at the port of Rochefort after a series of interesting trials, to which 

 reference will be made later. 



The general view of the dredge is given in Figs. 15 and 16. 



It is provided with a single inclined central ladder, and is fitted 

 with two screws. 



The engines are of sufficient power to give a speed to the vessel, 

 when loaded, of 6 knots, and to insure an efficiency, under unfavor- 

 able conditions of weather, of a minimum of 330 cu.yds. of compact 

 mud such as forms the bottom of the River Charente, at a depth of 

 33 ft. below the surface. 



The hull is constructed with an open end to provide a passage 

 for the ladder, and to allow the dredge, in case of necessity, to make 

 its own channel as it advances; the position of the ladder can be 

 shifted in such a way as to .excavate against fixed works (such as 

 quay walls) 13 ft. in advance of the hull, in slight depths. 



The material raised is discharged through two side passages 

 on either side of the vessel. 



The hull, which is built entirely of steel, has the following 

 principal dimensions: 



Ft. In. 



Length on deck 144 6 



Width 32 9 



Depth 11 2 



The hull is divided into nine compartments by eight watertight 

 bulkheads. 



The internal fittings of the vessel for the officers and crew are 

 very complete; they comprise a cabin for the engineer in charge, 

 which also serves as the watchroom, placed on the upper deck; the 

 captain's cabin is on the main deck; beneath the upper deck is a 

 large messroom for the officers; and on each side is arranged the 

 accommodation for the engineers, the dredging staff, and the crew. 



The propelling machinery consists of two compound surface- 

 condensing engines of the steam-hammer type, capable of developing 

 together 500 horse-power. 



These engines are arranged either to drive the scows or the 

 dredging machinery, a simple and quick-acting system of clutches 

 being provided to make the connections with one or the other. 



