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Basic principles of the mooring programme….

Moorings are used primarily to protect vulnerable sea floor structures and as a secondary benefit they make mooring visiting boats easier. Around the Seychelles islands, at this stage of the of the project, the positioning of moorings is determined by the need to protect sea floor structures of biological and ecological importance. 

The mooring system chosen uses various embedment mooring technologies proven by specialists John and Judy Halas of Environmental Moorings International, Florida. The equipment used depends on the bottom composition: in sand areas  'Manta Ray' anchors are used, while in granite and limestone areas stainless steel pins are preferred which are secured either by marine cement or by epoxy cement

The moorings are installed by members of the MCSS,  the Seychelles Ministry of Environment Marine Unit and Marine Parks Authority staff and are inspected and maintained by the MCSS according to an agreed inspection and maintenance schedule.

	A typical pin mooring installation

These moorings rely on anchor systems that are embedded into the bottom substrate and do not have heavy ground tackle dragging on the sea bed. Because of this they are particularly suited for use around coral reefs and other sensitive areas. 

Each mooring is designed for the particular site where it is to be installed and typically consists of  the following components:

• An anchor unit or anchor pin
• A heavy duty mooring line, with a float attached a metre or so from the anchor point to keep the line off the sea bed
• A surface buoy  on a looped bridle, to make it easy to maintain
• A floating pick-up line for boats to tie up to.

Installation techniques….

Load-locker in operation on a manta-ray installation.

In sand and small sized rubble the Manta ray anchors are utilised; these are essentially long toggle bolts that are driven 2 metres (6 feet) into the sea-bed by a hydraulic jack hammer. The the blade or toggle of the anchor is then locked out into position by a hydraulic load-locker;  at the same time as opening the toggle blade, this device also strain tests the installation. Once locked out,  the ground tackle of the mooring installation can then attached straight away and the mooring put into use.

On granite surfaces a modified hammer drill is used to drill a hole for a pin anchor to be placed  in. For limestone or coral bed-rock, a carbide tipped corer is used to form the larger diameter hole necessary for the t-bar pins that are normally used.

Once the holes are drilled the pins are then cemented in using either a special underwater epoxy cement or a conventional marine cement. Once  poured into the hole the mooring pin has to be left for several days until the cement has cured before the rest of the installation can be attached.

Progress to date….

So far personnel from the MCSS,  the Seychelles Ministry of Environment Marine Unit and the Marine Parks Authority have been trained in the installation techniques needed for the different moorings. A total of 42 moorings have been installed with  further moorings to be installed on an on-going basis.