Perth Bermuda Experiment - Maps #1
Some pretty pictures.
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The start of the journey.
This diagram shows (starting at the bottom of the diagram - after all, this is the bottom of the world):-
The location where RV Vema dropped her 200lb depth charges.
The location where HMAS Diamantina dropped her 300lb depth charges.
The 2 points that are the Antipodal Points of the Bermuda hydrophones Golf & Juliet.
The various coloured lines show some of the many possible sound paths available between the Antipodal Points and the hydrophones near Bermuda.
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The start of the journey.
This diagram shows (starting at the bottom of the diagram - after all, this is the bottom of the world):-
The location where RV Vema dropped her 200lb depth charges.
The location where HMAS Diamantina dropped her 300lb depth charges.
The 2 points that are the Antipodal Points of the Bermuda hydrophones Golf & Juliet.
The various coloured lines show some of the many possible sound paths available between the Antipodal Points and the hydrophones near Bermuda.
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Perth, Australia is at a Latitude of about 33 degrees South.
Cape Town, South Africa is also at a Latitude of about 33 degrees South.
Question: If you wanted to sail from Perth to Cape Town, in what direction would you set out from Perth? North-West? West? or South-West? This diagram shows that 'South-West' is the correct answer!! It's counterintuitive, but true.
Near the bottom of the page, some of the obstacles are apparent - The larger Kerguelen Islands, and the smaller Heard Island and MacDonald Island below and to the right. In 1991, Heard Island was the location of an experiment (similar to the Perth Bermuda Experiment) to test whether long range underwater acoustic communication was feasible, and to test whether the use of measurements of the change of the speed of sound underwater over long time periods will give an indication of the change of the gross temperature of the oceans caused by climate change. It appears that the answers are 'No' and 'Yes'!! (Link Heard Island Feasibility Test)
Perth, Australia is at a Latitude of about 33 degrees South.
Cape Town, South Africa is also at a Latitude of about 33 degrees South.
Question: If you wanted to sail from Perth to Cape Town, in what direction would you set out from Perth? North-West? West? or South-West? This diagram shows that 'South-West' is the correct answer!! It's counterintuitive, but true.
Near the bottom of the page, some of the obstacles are apparent - The larger Kerguelen Islands, and the smaller Heard Island and MacDonald Island below and to the right. In 1991, Heard Island was the location of an experiment (similar to the Perth Bermuda Experiment) to test whether long range underwater acoustic communication was feasible, and to test whether the use of measurements of the change of the speed of sound underwater over long time periods will give an indication of the change of the gross temperature of the oceans caused by climate change. It appears that the answers are 'No' and 'Yes'!! (Link Heard Island Feasibility Test)
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Kissing the tip of Africa.
The Kerguelen Islands are quite visible in the centre of the diagram. To the left (Just above the upper red line are the Crozet Islands, while just visible further to the left, above the white line is Marion Island (part of the Crozet Group).
Kissing the tip of Africa.
The Kerguelen Islands are quite visible in the centre of the diagram. To the left (Just above the upper red line are the Crozet Islands, while just visible further to the left, above the white line is Marion Island (part of the Crozet Group).
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The boring South Atlantic Ocean.
Although there appear to be some bottom topography that could impede the passage of sound, the features are all in very deep water.
The boring South Atlantic Ocean.
Although there appear to be some bottom topography that could impede the passage of sound, the features are all in very deep water.
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Sliding past Brazil.
The islands off the tip of Brazil, Ilha Fernando de Noronha and others, are all, like Bermuda, sitting on seamounts rising from very deep water, and should not pose too serious a barrier to the transmission of sound.
Sliding past Brazil.
The islands off the tip of Brazil, Ilha Fernando de Noronha and others, are all, like Bermuda, sitting on seamounts rising from very deep water, and should not pose too serious a barrier to the transmission of sound.
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The home stretch.
3 hours and 43 minutes later!!
The locations of the hydrophones 'Golf' and 'Juliet' are shown, as well as the headquarters in St. David's.
The home stretch.
3 hours and 43 minutes later!!
The locations of the hydrophones 'Golf' and 'Juliet' are shown, as well as the headquarters in St. David's.
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A picture showing the ocean bottom profile along the track. Australia is on the left side of the diagram, Bermuda is on the right.
Extract from "Another look at the 1960 Perth to Bermuda long-range acoustic propagation experiment." Brian D Dushaw, Applied Physics Laboratory. University of Washington, Seattle, WA 98105, USA.
Posted Oct 2020
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