The network, owned and operated by Marine Rescue NSW, covers the state's coastline, with the Far South Coast work set to eliminate the last remaining major blackspot.

Communications equipment is being installed on Boyne Trig south-west of Ulladulla, Dr George Mountain near Bega, reservoirs at Bermagui and Moruya and Round Hill south of Batemans Bay.

"This is the final frontier," MRNSW Emergency Systems Manager Andrew Cribb said.

"These are the last major blackspots that we are filling in."

The work is being completed by Tuggerah-based Karera Communications.

"Once the South Coast projects are finished, we expect to have consistent marine radio coverage along the NSW coastline from Point Danger to Eden, 20 to 30 nautical miles out to sea," Mr Cribb said.

"It's a win for boaters inshore and offshore.

"If they are in a coastal region and something goes wrong, they'll be heard on VHF marine radio 24/7."

MRNSW Monaro Regional Operations Manager Glenn Sullivan said the rugged coastline south of Bermagui Harbour was a notorious marine radio blackspot.

"The communications equipment being installed on top of the Bermagui Reservoir will provide coverage from outside Bermagui Harbour south towards Tathra," he said.

As well as local boaters, this year's Sydney to Hobart fleet should experience superior reception as it transits the South Coast thanks to the communications upgrade.

MRNSW and the Cruising Yacht Club of Australia's Safety of Life at Sea Trusts are funding the installation of the new VHF infrastructure.