This 1933 cover photo shows workers maneuvering a bomb into position on a platform in San Francisco Bay, at a very early stage of the Golden Gate Bridge project.

The location of the bridge’s south pier, 1,000 ft offshore, was in water 50 ft to 60 ft deep.

Plans called for removing 30,000 cu yd of rock, to reach a depth of 100 ft. A six-man crew worked from a 42 ft x 140 ft barge with derricks and winches operating cables connected to six, 5-ton anchors.

The 5,000-lb bomb consisted of a 20-ft-long, 8-in.-dia steel tube containing about 2 tons of concrete which on impact would trigger the firing pin to set off the 250 lbs of high explosive.

A 14-in.-dia steel pipe, with steel legs at the bottom, known as a bombing barrel, was positioned and used to aim each bomb.

The bombs were targeted at 20 ft intervals and afterwards the shattered serpentine rock was removed from the bay by clamshell dredges.