Marine Rescue NSW Inspector Glenn Sullivan said a volunteer crew on board Merimbula 31 was returning to base after completing a rescue half a kilometre off Middle Beach when they were contacted by a skipper whose vessel was taking on water.

"The crew safely returned three anglers to South Merimbula boat ramp and their vessel after it suffered mechanical failure earlier this morning.

"Shortly after 10am, radio operators at Marine Rescue Merimbula took a request for assistance from a man on board a 36 foot flybridge cruiser that was taking on water north of Tathra."

Inspector Sullivan said Merimbula 31 was immediately redeployed to assist.

"Following an initial assessment of the situation, the skipper of the distressed vessel was supplied with an emersion pump to assist with removing water from inside the vessel.

"He was also wearing a lifejacket and had an EPIRB and flares ready to activate if required.

"MB 31 shadowed the distressed vessel north towards Bermagui as the harbour has slipway facilities.

"MB 31 and the distressed vessel were met by volunteers from Marine Rescue Bermagui on board BG 30."

Inspector Sullivan said the vessel was still taking on water but it was being managed as the Bermagui crew shadowed it into Bermagui harbour..

"Because of the care that must be taken to get this vessel back to harbour, we expect the mission to take at least another two hours with an ETA just after 4pm," Inspector Sullivan said.

During the joint response from Marine Rescue Merimbula and Bermagui, Marine Rescue NSW was also requested by Marine Area Command to search for a 4.4 metre runabout, which capsized off Haycock Point Monday morning.

"Thankfully the two persons on board made it to shore themselves and have been retrieved by rescue helicopter," Inspector Sullivan said.

"Marine Rescue NSW vessel Merimbula 31 began searching for the overturned vessel on Merimbula Bay, but the boat has since washed up on the northern side of Haycock Point.

"The dedication, professionalism and teamwork shown by our volunteers from the Merimbula and Bermagui units has been exceptional," Inspector Sullivan said.

Marine Rescue NSW is a volunteer based not-for-profit professional organisation dedicated to keeping boaters safe on the water and supporting local communities.