Another powerful and successful sand-pump dredger, "Kate" (Plate I. fig. 7), was built in 1897 by Messrs Wm. Simons & Co. Ltd. for the East London Harbour Board, South Africa. Its dimensions are: length 200 ft., breadth 39 ft., depth 14 ft. 6 in., hopper capacity 1000 tons. The pumping arrangements for filling the hopper with sand or discharging overboard consist of two centrifugal pumps, each driven from one of the propelling engines. The suction pipes are each 27 in. in diameter, and are so arranged that they may be used for pumping either forward or aft, as the state of the weather may require. Four steam cranes are provided for manipulating the suction pipes. Owing to the exceptional weather with which the vessel had to contend, special precautions were taken in designing the attachments of the suction pipes to the vessel. The attachment is above deck and consists of a series of joints, which give a perfectly free and universal movement to the upper ends of the pipes. The joints, on each side of the vessel, are attached to a carriage, which is traversed laterally by hydraulic gear. By this means the pipes are pushed out well clear of the vessel's sides when pumping, and brought inboard when not in work. Hydraulic cushioning cylinders are provided to give any required resistance to the fore and aft movements of the pipes. When the vessel arrived at East London on the 18th of July 1897, there was a depth of 14 ft. on the bar at high tide. On the 10th of October, scarcely three months afterwards, there was a depth of 20 ft. on the bar at low water. Working 22 days in rough weather during the month of November 1898, the "Kate" raised and deposited 2½ m. at sea 60,000 tons of dredgings. Her best day's work (12 hours) was on the 7th of November, when she dredged and deposited 6440 tons.
A large quantity of sand-pump dredging has been carried out at Boulogne and Calais by steam hopper pump dredgers, workable when the head waves are not more than 3 ft. high and the cross waves not more than 1½ ft. high. The dredgings are taken 2 m. to sea, and the price for dredging and depositing from 800,000 to 900,000 cub. metres in 5 or 6 years was 7.25d. per cub. yd. The contractor offered to do the work at 4.625d. per cub. yd. on condition of being allowed to work either at Calais or Boulogne, as the weather might permit. Sand-pump dredging has also been extensively carried out at the mouth of the ports of Amsterdam, Rotterdam and on the north coast of France by sand dredgers constructed by Messrs L. Smit & Son and G. & K. Smit. The largest dredger, the "Amsterdam," is 141 ft. by 27 ft. by 10 ft. 8 in., and has engines of 190 i.h.p. The hopper capacity is 10,600 cub. ft., and the vessel can carry 600 tons of dredgings. The pump fan is 6 ft. 3 in. in diameter by 10 in. wide, the plates being of wrought iron, and makes 130 revolutions a minute. The pump can raise 230 cub. ft. a minute from a depth of 33 ft., which, taking the proportion of 1 of sand to 7 of water, gives a delivery of 29 cub. ft. of sand per minute. The hopper containing 10,600 cub. ft. was under favourable circumstances filled in 40 minutes. The vessels are excellent sea boats.