A team of eight rowers hope to row 100 miles (161km) from St Kilda to Skye in a renovated 120-year-old rowing boat.
The crew have been waiting for calm weather before making their attempt. Forecasts suggest conditions this weekend will be favourable and they plan to set off for Skye early on Friday morning.
Until last month, the last time the rowing boat was in the sea was more than 100 years ago.
Named Aurora, the 20ft-long (6m) skiff had lain in a boat shed on Skye since before the outbreak of World War One.
Last year, boat builder Iain MacLean restored the craft. He replaced most of its structure, but managed to save almost all its larch planking. It was named Aurora and re-launched in April this year.
Before last month, the last time the boat had been used was to help passengers chase and catch up with a Glasgow steamer they had missed at Portree on Skye in 1913.
Donnie Nicolson is leading the St Kilda to Skye challenge. He said: "The weather is my biggest worry, then followed by 'will the boat stand up to it?', then last, 'can the crew pull it off?'. We have a good team in place. I'm confident they're up to the task." Five of the eight crew are volunteers with Portree lifeboat.
St Kilda is a remote archipelago dubbed Scotland's 'Lost World'. Its last 36 human residents were evacuated in 1930 and today only National Trust for Scotland staff and volunteers, scientists and Ministry of Defence contractors stay on its main island of Hirta for a few months at a time. The group of islands are home to large numbers of seabirds, a rare species of mouse and sheep.
The rowers, who are raising money for the RNLI and Skye and Lochalsh Young Carers, will have a support crew with them. They hope to leave St Kilda on Friday and complete their journey in about 38 to 48 hours. The rowers have spent two years preparing for the venture. Crew member Jamie Kirkwood said one of the hardest parts of their training had been a 24-hour row. He added comfy seats would be key to the attempt being successful. Mr Kirkwood said: "When we were training on rowing machines in the gym we sat on pillows."
Mr Nicolson said: "Our boat is an old lady and will have to be treated with care." He added: "In the open water of the Atlantic Ocean, when St Kilda has been left behind, our 120-year-old boat will feel very small."