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World War 2, Western Australia, Rottnest Island, Coast Artillery Instrumentation, Fortress Plotter (Aust) 101 Mk1
Overview
Fortress Plotter (Aust) 101 Mk 1. This plotter was installed when radar was introduced to the Island. It is a largwe scale vertical plotter which gives the coordinates of a target when supplied with ranges from two fortress observation posts. It was more accurate than optical instruments especially when visibility conditions were unsatisfactory.
The plotter consisted of a map gridded chart of the fortress area with three fortress observation posts acting as pivot points – Tree Hill, West End and Bare Hill. A pair of range arms were swung from any combination of two pivot points and the coordinates of the target were read from the intersection of the arms using a roamer . The coordinates were then distributed to the selected engaging battery by the fortress commander
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-32-54-686
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.
Geotag
-32.008490251366, 115.51400708229
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Nearest geotagged records:
- World War 2, Western Australia, Rottnest Island, Coast Artillery Instrumentation, Encoder - Fall of Shot Mk 1 (0km away)
- World War 2, Western Australia, Rottnest Island, Coast Artillery Instrumentation, Fortress Plotter No 2 Mk1 (0km away)
- World War 2, Western Australia, Rottnest Island, Coast Artillery Instrumentation, Fortress Plotter (Aust) No 102 Mk1 (0km away)
- World War 2, Western Australia, Rottnest Island, Oliver Hill, Fortress Plotting Room (Primary), Layout, 1942 (0km away)
- World War 2, Western Australia, Rottnest Island, Oliver Hill, Plotting Room Complex, 1938 / 1942 (0km away)
- Inter War, Western Australia, Rottnest Island, Oliver Hill. Construction, 1937 (0.1km away)
- World War 2, Western Australia, Rottnest Island, Oliver Hill Battery, H2 Front View (0.1km away)
- Inter War, Western Australia, Rottnest Island, Military Railroad. Oliver Hill Battery, Spur Line to Engine Room entrance (0.1km away)
- Inter War, Western Australia, Rottnest Island, Oliver Hill Battery. 6 Heavy Battery, Royal Australian Artillery. Gunner A TROTT and Gunner H INGRAM (0.11km away)
- Inter War, Western Australia, Rottnest Island, Oliver Hill.H1 gun. Installation (0.11km away)
View all geotagged records »
Australian Army Museum of Western Australia
Australian Army Museum of Western Australia
Other items from Australian Army Museum of Western Australia
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World War 2, Western Australia, Rottnest Island, Coast Artillery Instrumentation, Encoder - Fall of Shot Mk 1
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World War 2, Western Australia, Rottnest Island, Coast Artillery Instrumentation, Fortress Plotter No 2 Mk1
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World War 2, Western Australia, Rottnest Island, Coast Artillery Instrumentation, Fortress Plotter (Aust) No 102 Mk1
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World War 2, Western Australia, Rottnest Island, Oliver Hill, Fortress Plotting Room (Primary), Layout, 1942
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World War 2, Western Australia, Rottnest Island, Coast Artillery Instrumentation, Depression Position Finder Type T Mk2
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World War 2, Western Australia, Rottnest Island, Coast Artillery Instrumentation, Depression Position Finder Type 5 Mk1
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World War 2, Western Australia, Rottnest Island, Coast Artillery Instrumentation, Decoder - Fall of Shot Mk 2
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World War 2, Western Australia, Rottnest Island, Coast Artillery Instrumentation, Stereoscopic Telescopes
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World War 2, Western Australia, Rottnest Island, Coast Artillery Instrumentation, Indicator – Time of Flight Mk 1
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World War 2, Western Australia, Wadjemup Hill / Signal Ridge, Battery Observation Post, Layout
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World War 2, Western Australia, Rottnest Island, Coast Artillery Instrumentation, Director No 10
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World War 2, Western Australia, Rottnest Island, Fortress Observation Post "Flame", Cape Vlamingh Layout, 1942
Layout of Oliver Hill Fortress Plotting Room
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