The initial project that MACS will undertake to achieve is the implementation of screw anchors for the aquaculture and commercial industry in Melbourne.
Screw anchors have been used throughout the world for many applications both on land and into the seabed. Initially anchors that were installed into the seabed used a diver operated drill. Having a diver bought with it some serious issues regarding OH&S, extra equipment on board, was time consuming and added an additional cost.
Therefore, the next development step was to remove the diving component which in turn would result in a faster and most cost effective operation. All screw anchors are now installed totally driverless.
The screw anchor is designed to screw into almost any soft surface seabed. The screw anchor rig consists of a surface unit with a stand-alone diesel power unit running the pneumatics and hydraulics. The machine is connected to the subsurface drill unit via a 50-metre umbilical. This unit is controlled by the operator using underwater camera and has a fine degree of control, allowing gentle and correct placement of the drill unit, minimising any potential environmental damage. The rigging doesn't contact the seabed as it goes straight up towards the surface where it is attached to a buoy.
MACS has designed and built a screw rig specifically for the aquaculture and commercial industry. Installation begins with a consultation to work out what size anchor is required for the area in question, also the precise position. Screws are then positioned using our DGPS and installed. For best results surface infrastructures are connected 2 days afterwards to anchor warps, which would allow for settling of the seabed.
Screw anchors are positioned using a DGPS which results in precise positioning of each application. Underwater video backup is also used to verify correct installation. Screw anchors also have a superior holding ability in comparison to concrete weights and have a less warp ratio. With a steeper angle on the warp there is no contact with the seabed.
This new eco-friendly system could become common practice throughout Victoria. Single-point screw anchors permanently drilled into the seabed and connected to floating buoys can be used in various ways by small or large vessels and commercial application. The steel shaft screw anchors are sunken 3 to 4 metres into the seabed using a custom designed underwater hydraulic drill rig.
The environmental impact of the screw anchor is negligible, and many have been installed throughout Australia where any other type of anchor would not have been allowed. The major environmental advantage of the anchor is the avoidance of chain-drag on the seafloor there for reducing seagrass erosion. After installation the only visible evidence of the screw anchor on the seafloor is a small "footprint" and the anchor warp.