Another two life rings have also been donated, one of which might be installed at Puddingstone Rock.
Kane Harvey (15), his step-father, David Moses, and fellow fisherman Cory Ferguson spent more than an hour floating at sea with a life ring before being rescued by the Otago Regional Rescue Helicopter on May 27.
Kane and Mr Moses were swept off rocks at Cape Saunders while collecting mussels for bait and Mr Ferguson jumped in the water to help them.
Kane's best friend, Micah Wharerimu (14), was also fishing and threw Mr Ferguson the life ring installed at Cape Saunders by Coastguard Dunedin. The life ring was not recovered.
Coastguard Dunedin president and senior constable Lox Kellas, of Portobello, said a replacement life ring was sourced from Christchurch and installed at Cape Saunders soon after the incident.
A family, not from Dunedin, which had lost a member to drowning many years ago donated a life ring to Coastguard Dunedin, he said.
"Then some local guys got together and gave us another one. People have been very generous," Mr Kellas said.
With one to be a back-up for Cape Saunders, the third life ring might be installed at Puddingstone Rock on Otago Peninsula before summer, he said.
Weather and sea conditions had been too rough to search the coastline for the original life ring, but it could still turn up.
Life rings each cost a few hundred dollars and the first one installed at Cape Saunders was funded by a community board grant.
