3°
DOCK ENGINEERING.
The deep water channel extends from New Brighton, on the left bank,
at which place the river is 5,600 feet wide, to Dingle Point, on the right
bank, where the width is 7,200 feet. At an intermediate point opposite
the centre of Liverpool, the width becomes reduced to 3,000 feet.
Throughout this distance there is ample depth of water for vessels at all
stages of the tide, the depth at low water of ordinary spring tides being
70 feet, 40 feet, and 50 feet at the above-mentioned stations respectively.
On the Liverpool side, unfortunately, this deep channel is bordered by a
sand bank, known as the Pluckington Bank, which shoals the river bed
to such an extent as to seriously diminish the value and utility of the
central docks, and interfere with the use of the passengers’ floating landing-
stage, which flanks the river quays at this part. Various remedial ex-
pédients have been tried from time to time, but whatever success has been
obtained has never been otherwise than of a temporary nature.
The navigable depth over the crest of the bar of the river at the present
date is 27 feet at lowest low water of ordinary spring tides. This result
has only been obtained by a vigorous policy of continuous dredging with
sand pumps. Rather more than a decade ago the navigable depth was
only 10 feet at lowest low water of spring tides.
The range of tide at Liverpool is 31| feet at equinoctial springs, 271 feet
at ordinary springs, and 13 feet at ordinary neaps. The local datum is the
Old Dock sill, 4 feet 8 inches below ordnance datum. The Old Dock has
long since disappeared, but the level of its sill has been scrupulously
preserved.
The following table presents a succint but complété statement of the
extent of accommodation afforded by the Liverpool and Birkenhead Docks
at the present time :—