The Wreck of the Illinois
The Illinois, whose wreckage is illustrated here, was a sand dredge that operated in Lake Michigan sometime in the late 1920's or early 1930's.
Very little is known about her but a few facts and some speculation.
It is known that the Illinois was not self-propelled. She was probably maneuvered into position over a likely sandy bottom area by tugboats.
She was made of two basic parts -- a working foredeck, followed by a barge-like sand receiving area.
It is surmised that the boom supports formed an "A" frame-type structure that supported a pulley mechanism.
Electric motors would wind and unwind cable through the pulley to raise and lower the boom.
When it was lowered, the boom would tilt down toward the floor of the Lake, carrying the three-bladed auger into the sand.
A drive shaft in the boom would turn the augers while the centrifugal pump would pump a slurry of sand and water to the surface where it was dumped into the barge.
We've had to make a few assumptions since all the Illinois' mechanical gear has been salvaged.
1. A centrifugal pump, like the 12-foot diameter pump still on board, had to turn at a high rate of speed in order to pump slurry to the surface.
2. The only way to turn a pump of this size, at high speed, would be with an electric motor. There remain empty machinery platforms in the wreck that could have supported such electric motors.
3. In order to turn an electric motor, a generator was needed. Here again, vacant machinery platforms in the wreck might have held such a generator.
4. In order to turn such a generator, a steam-powered turbine was required. It too, if it ever existed, has been salvaged.
You'll be amazed at the size of the centrifugal pump. It stands at an acute angle where it tilted from vertical upon hitting the Lake bottom.
A trip down the boom to the augers is interesting and easy. Even though little is known about the Illinois -- as it was only a sand dredge, not a glamorous sailing ship -- it is a fascinating wreck to explore.
Research and article by Sam Frank
Dive into History - Take Only Pictures - Leave only Bubbles
Copyright 1996 - The Underwater Archaeological Society of Chicago