Scope of work
PMG undertook the salvage of the 120 year old and 28m long timber ketch "Defender" which had sunk on its moorings in January 2016. The vessel had sat on the Ross Creek seabed in Townsville CBD for 11 months before PMG was contracted to undertake the recovery and removal works.
PMG developed a plan to refloat the vessel and then relocate it to a nearby disused slipway, which would need to be reinstated so the vessel could be removed from the water.
In preparation for the task an assessment of the slipway and associated winch and rail system was undertaken, which revealed that the existing infrastructure could be made operational again, with minimal work required and a generator wired in to power the electric motor. Additionally, some rudimentary strengthening works would be undertaken to the badly corroded carriage way beams and track system to ensure the carriage held together for the removal.
Refloating was achieved by patching all accessible holes in the hull and installing a series of air bags, mounted low in the water along both sides of the vessel, within a steel support framework that was lashed down to the gunnels. This preparation work was undertaken after all the rigging had been removed and the two masts unstepped to reduce the risk of the vessel rolling during the recovery operation.
The refloating operation was scheduled to coincide with a low tide once the 10 lift bags were secured in position. Pumps were then used to pump out the hull as air was introduced into the lift bags, which was successful in raising the Defender from the seabed.
Once refloated the vessel was assessed for structural integrity before approval was sought from the Regional Harbour Master to attempt to move the now floating vessel to the slipway.
A containerised dive spread and salvage support equipment, including a 150T crawler crane all loaded aboard our 45m barge “PMG150” were used to support the operation. The work was also supported by our harbour tug “Swordfish” and various other smaller work vessels.
The Pacific Marine Group site crew comprised of a project manager, 4-person marine crew, and 4 commercial divers, who were supported by all departments of the company.
The vessel was then positioned over the submerged slipway trolleys and then the winch used to pull the vessel up the rails and out of the water.
Once up on the slipway the casualty was secured using additional Acro props down both sides of the vessel to ensure it was safe and secure for handover to MSQ.
The refloating and removal operation was successfully completed in less than 1 week from commencement, with much of the preparation undertaken at night to coincide with low tides which offered best access to the vessel.
Following the recovery MSQ requested PMG undertake high pressure cleaning of all external surfaces of the vessel as a variation to the original contract. This additional work took 3 days to complete, during which time a fence was erected around the vessel to secure the vessel and associated rigging and to ensure the safety of the public.
