Environmental Moorings Offshore Cairns

Scope of work

Purpose: Provide environmentally friendly Public Moorings at selected sites around the Cairns area.

Description of Works by PMG:

  • Undertake the fabrication of our 4m long Environmental Mooring pins in our Townsville workshop,
  • Preparation of all materials, equipment and crew for transportation to the installation sites selected by QPWS,
  • Undertake installation of 13 x Grouted Screw Moorings at the preselected sites as follows:
    • SudburyCayx2
    • FitzroyIslandx7
    • GreenIslandx2
    • Vlasoff Cay x 2
  • These environmentally friendly moorings were installed into the seabed by commercial divers operating our specially designed Hydraulic Underwater Mooring Machine (HUMM).
  • The diver is supported by a topside crew that pumps grout, via an umbilical, down through the mooring pin as it is screwed into the seabed.
  • The rotation of the pin mixes the grout with the substrate material to form a column of concrete 4m deep with a 0.6m diameter.
  • Once the concrete has cured a selection of the installed mooring pins were load tested using a 6 tonne vertical load, to confirm they have achieved the required holding power.
  • Specialised mooring tackle was then connected to the mooring’s pad eye, at seabed level. This tackle uses a floating line that is suspended vertically using a subsurface buoy to provide catenary action for the vessels using the moorings. This has the effect of minimising shock loading during adverse weather conditions.
  • The moorings were installed for use as Public Moorings at selected high use sites in the local Cairns area of the Great Barrier Reef Marine Park.

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11 - 23 Oct 2016

Case Study

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