Throughout the Remotely Operated Vehicle session Flatholm was moored on a four point mooring above the wrecks to be surveyed.

The vessel's two bow anchors were used at the front and two 200kg high power holding anchors with short lengths of chain were deployed at the stern. Two hydraulic winches were used to handle the stern mooring.

For the mooring procedure a computer file (.dxf) showing the wreck outline visible in the geophysical survey was displayed in the vessel navigation software package on the bridge. Points were taken where anchors were to be dropped, so as to avoid damage to the wreck. However it was not always possible to avoid mooring wires crossing the wreck site.

As the two 200kg anchors used as stern mooring during the Remotely Operated Vehicle session proved insufficient to hold MV Flatholm on station in strong tides and less favourable weather conditions, two sinkers of 2t and 3t respectively were bought for the diving session.

A 40m length of chain with a buoy and a shackle at the end was attached to each sinker. The use of sinkers required a lengthy mooring procedure to avoid dragging long wires through the water and damaging wreck sites.

On arrival on site, the two buoyed sinkers were dropped on one side of the wreck and their positions marked. The vessel than deployed the bow anchors on the other side of the wreck site and then dropped back. Then the stern winch wires were connected to the sinkers using a small rigid inflatable boat.