295 OF ENGINEERINC4 FORMULÆ.
Docks.
Ordinary docks vary from 3 to 30 acres, with,
from 400 to 2000 lineal yards frontage.
Locks: 40 to 80 feet width.
25 „ 30 „ depth on sill.
400 „ 600 „ length.
Graving docks: from 45 to 100 ft. width.
30 „ 35 „ depth on sill.
500 „ 700 „ long in blocks.
Clark’s hydraulic dock : ■
Poutpons from 150 to 320 feet long x 59 feet broad.
Floating docks (graving), Rennie’s:—
350 feet long; width inside, 76 feet; width
outside = 105 feet.
Depth over keel-block when sunk = 28 feet.
8 pumps: 33-incli stroke, 26 inches diameter.
2 engines: high pressure, 18-inch cylinder,
2-feet stioke.
BERMUDA FLOATING DOCK.
Length
Breadth
Depth
Outside. Inside Dimensions.
381 feet .. 380 feet.
124 „ .. 84 „
72 „ .. 52 „
Pressure on Lock Gates, &c.
D = Depth of water on gate in feet.
P = Pressure on gate.
A = Area of surface exposed to the water in
square feet.
P in lbs. = A X 31'2 D.
P in cwts. = A x ’278 D.
Beat angle for lock gates = about 136°, or a
ratio of rise to span = 1 to 5.
For circular gates the best ratio of rise to
span = 1 to 3.