Debris has reportedly been seen in the Atlantic Ocean, in the area where UK yacht the Cheeki Rafiki went missing with four British sailors on board.
Patrick Michel, the captain of a volunteer crew taking part in the search, said details of what was spotted were passed on to the US Coast Guard.
A spokeswoman for the US Coast Guard said: "I can confirm that we have received reports (of debris) from the sailing vessel Malisi. They have found some debris in the search area. We can't tell at this time if they are from the Cheeki Rafiki as there were no identifying marks on them.
"The debris was a plank of wood and a small piece of floating foam, but there was nothing identifying the Cheeki Rafiki. Obviously it is a possibility, and we are definitely treating it very seriously and incorporating that into our search, but I can't say for certain that it was from the Cheeki Rafiki."
The spokeswoman confirmed the debris was spotted in the search area outlined by the US Coast Guard, but could not say if it was in an area already searched.
Mr Michel told BBC Surrey: "We are currently just in the north part of the search area, our third night out here, and we did see during this night a few little (pieces of) debris which I have reported to the US Coast Guard with the times and positions, so there is a little bit of light at the end of the tunnel."
The experienced crew, aged between 22 and 56, were on the 40ft yacht when it capsized in the Atlantic Ocean on Thursday.
The US coastguard called off search efforts involving ships, planes and helicopters on Sunday morning in severe weather, to the dismay of the men’s families.
Relatives of the four men Andrew Bridge, 22, from Farnham, Surrey and crew members James Male, 23, from Southampton, Steve Warren, 52, from Bridgwater and Paul Goslin, from West Camel, 56 pleaded with the US Coast Guard to resume the search and remain convinced that their loved ones are alive.
Kay Coombes, the sister of Mr Warren, welcomed the reports that debris had been spotted.
She told BBC Breakfast: "I think they've got a bit more of a clue now so hopefully the coastguard can plot that and get the ships to that area, so fingers crossed they can start searching there."
She said the families of the missing sailors were still clinging on to hope, and thanked Mr Michel for taking the time to search and the coastguard for redoubling its effort.
"They are still out there, there's more resources being put into it, so we're still hopeful at this point," she said.
She added: "We have got to stay positive. We are still hopeful, we are clinging on to that. We are just keeping going. It is exhausting now, this has been going on for days. We are mentally exhausted, physically exhausted, I think we are running on coffee now rather than anything else, but we are still going, we are still there for him."
Ms Coombes said relatives of the missing sailors were meeting officials in London today.
Coastguards said 9,000 square miles had been searched by Wednesday and an RAF plane joined the search yesterday, alongside three planes and six ships.