A Treatise On The Principles And Practice Of Dock Engineering

36 DOCK ENGINEERING. TABLE IV. —Barry Docks. Depth of Water on Sill. Depth of Water on Sills, Outer and Middle Gates. l.w.o.n.t. h.w.o.s.t. l.w.o.s.t. h.w.o.n.t. Ft. Ins. 49 8 z---- 53 8 Ft. Ins. i Ft. Ins. 13 7 41 4 In Channel. 17 7 I 45 4 Ft. Ins. 21 8 25 8 Width of Entrance Gates. Quayage. Width. Length. Area. Description. Ft. Ins. 29 4 29 4 29 4 Ins. O ) 00 00 Ft. .37 37 37 □ooom : ; <X> CO CO 00 O • ■ .oo o ^oo^ - SS 51000 : 00 F 10, 7. 2. oi 10 . O 0 O »0 ■g 00 00 88 ^! I I —< .0 o o r- ■so 010 ^ 88 S^ co o o oo o ^CO CO ^H 1,500 Acres. 73 34 7 6 35 Dock No. 1, . . . „ No. 2, . ,, No. 3 (Basin),. Lady Windsor Lock, Tiniber Float, No. 1, „ „ No. 2, Entrance channel from the breakwater heads to deep lock gates, Note — The sills being curved, the depth of water at the centre of the sills ot that given above. Docks at Buenos Ayres. This system [of docks exem- plifies (see fig. 8) the case in which an enclosed basin has been rendered necessary by other than strictly tidal reasons. The average range of tide does not exceed 2 feet 7| inches, the highest recorded for four years being 3 feet in the month of December, and the lowest 2 feet 3^ inches in the month of June. The flood waters of the “ Santa Rosa,” however, cause the water to rise to a height of 8 feet above their normal height, and the river has been known to fall below zero to the same extent on one occasion at least. The principal reasons, therefore, which operated in favour of entrance locks are thus set forth by Mr. Dobson* :— “In the first place, the gates were provided, not so much with the object of maintaining the water in the docks at a nearly constant level, as for the pur- pose of preventing it from falling below the level of zero or low water, thereby enabling vessels always to remain afloat in the docks, and, at the same time, to allow all ships of light draught to leave them, if neces- sary, when the level of the river was below zero. In the second place, the southernmost pair of gates, which point outwards, are constructed with the object of preventing the water of the Riachuelo, when in a turbid * Dobson on “Buenos Ayres Harbour Works,” Min. Proc. Inst. C.E., vol. cxxxviii.