Trade-A-Boat – August 2019

TRADEABOAT.COM.AU | 59

FEATURE | HMAS DIVE SITES

requirements (in depths of about 30-35m) and

have minimal impact on commercial fisheries

or recreational activities commonly undertaken

in the area.

From an operational perspective, site feasibility

is dependent on its distance from the mainland,

proximity to on-shore infrastructure for dive

operations, water depth, clarity and temperature,

currents, prevailing wind and wave conditions, and

the socio-economic benefits likely to accrue to the

local community.

HOW TO SINK A SHIP

After a RAN warship is “paid off ”, it undergoes

a decommissioning process, which involves

declassification.

This sees the removal of classified security items such

as communications and signals processing equipment

and control consoles from weapons systems and

demilitarisation (removal of weaponry, radar systems,

sonar domes, missile launch units and engines).

The fuel tanks are also emptied and flushed with

soapy water.

By the time the vessel is ready for handover, it is

effectively a “dead” ship with no power or means of

propulsion, and is towed to a civilian dockyard for the

next stage of preparation.

To prepare a hulk for sinking as a wreck site,

several things must be done to make it safe for the

marine environment and divers.

In the absence of an Australian standard in this

regard, Australian authorities and contractors use best

practice guidelines developed in Canada and

the United States.

The scope of a pre-scuttling contract will usually

involve purging the vessel of all oils, hydraulic fluids

and greases; and removing all hazardous materials

such as polychlorinated biphenyls (PCBs), asbestos,

heavy metals, batteries, chemicals and plastics.

Additionally, much of the superstructure is

removed to eliminate overhead navigation obstacles

and prevent the hazard of it eventually caving in from

“Selecting a site for scuttling a vessel

to create an artificial reef involves

consideration of a wide range of factors.”

CLOCKWISE FROM BELOW Ex-HMAS Swan
thriving in its second lease on life; The business end of
Hobart on its final peace mission.