The naval diving unit searching for missing fisherman Willie Whelan is concentrating on an area ten nautical miles southwest of Hook Head as it attempts to locate the sunken trawler, the Alize.
The 41-year-old from Fethard-on-Sea in Co Wexford has been missing since the vessel went down on Saturday night.
Joe Sinnott, 65, died in the incident, which happened as the two men were coming towards the end of a scallop-fishing job they had begun last Friday morning.
The search for Mr Whelan has involved Coast Guard volunteers, lifeboat volunteers from Dunmore East, Kilmore Quay and Fethard-on-Sea, the R117 search and rescue helicopter based in Waterford, as well as the R116 helicopter from Dublin, along with local boats and others.
Navy divers arrived in Kilmore Quay on Tuesday and have since been carrying out an assessment of the area where the Alize is thought to have sunk, using sonar and remote-operated technology and using the LÉ Samuel Beckett as a base.
It is understood the LÉ Samuel Beckett has been in the same area about ten miles southwest of Hook Head for over a day.
However, the depth of the water, as well as expected poor weather conditions in the coming days, means an actual dive to the Alize, when its location is confirmed, may not be possible for several days.
Local boats and volunteers have been continuing their search for the missing fisherman.