World War 2, Western Australia, Rottnest Island, Coast Artillery Instrumentation, Fortress Plotter (Aust) No 102 Mk1

Overview

Fortress Plotter (Aust) No 102 Mk1 – This plotter is similar in appearance and style to the 101 plotter except it had only 1 plotting arms. It was used to convert bearing and range from a single fortress observation post into coordinates. Initially the fortress observation posts were equipped either with a depression position finder or a director No 10 to determine the bearing of a target.

Historical information

The Rottnest Island Fortress Plotting Room is a semi-buried complex within the Oliver Hill perimeter, built in 1936-38 and expanded in 1942.
A Fortress Plotting Room was where information about naval targets was received from Fortress Observation Posts, plotted and the required information extracted and then acted on. There are smaller plotting rooms associated with Bickley Battery which received information from the the Fortress Plotting Room and Battery Observation Posts.
The Fortress Plotting Room contained a Range-finding Exchange (telephone), Fortress Plotters to track shipping targets on charts, Fall-of-Shot Indicators, Fire Direction Table, Ballistic Correction Calculators and other equipment to collate incoming information about the type of target and its range, speed and course.

Details

Details

Registration number
cwa-org-32-54-689
Contextual Information

This entry is based on research, documentation and technical drawings prepared by John Mercer during many years as a leading member of the Rottnest Island Military Restoration Committee and the Defence Heritage Interpretation Plan Group.

Australian Army Museum of Western Australia

Australian Army Museum of Western Australia

Organisation Details
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Plotter
Layout
Plotting Room Door

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