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Accurate
charts essential
Most
“landlubbers” would have never heard of the “Brother’s
Patches”, “Gannet Passage” or the “East Cardinal
Mark.”
Yet knowing about them is an extremely important, even life-or-death,
factor for mariners who ply the waters of the Torres Strait north
of Australia.
The “two way” route is one of the busiest navigational
passages between Australia and the Far East.
Places like the “Brother’s Patches”, “Herald
Patches” and “Alert Patches” are ever moving sand
waves just beneath the surface.
Some protrude into the “two way” route.
Recent charts show one was just 9.6 metres beneath the surface.
To operators of a “tinny” this would be a safe depth but
to the master of a 200,000 tonne merchant ship it could be a grounding
if he did not carry a well-versed pilot and accurate charts.
The presence of the ever changing northern seabed is just one of
the reasons the RAN’s Hydrographic Service bases its six primary
ships at HMAS Cairns.
On average the Torres Strait shipping lanes are checked annually,
particularly where sand waves are known to be present.
Data gathered by the ships and supplemented by information supplied
from civilian vessels and the LADS aircraft, are sent to the Hydrographic
office in Wollongong where they are analysed and put into new charts.
Constant checks of the Torres Strait region are a must for this
service, the Hydrographer, CAPT Bruce Kafer explained.
In contrast charts derived from Flinders’ circumnavigation
of Australia are still in use in some areas including the most northern
shoreline of the Great Australian Bight.
This is because large vessels don’t venture into the region
and the water is known to be deep.
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