Conservationist Sacha Dench is part of a team tracking the bird to learn more about the species’ behaviour.
She told BBC Radio’s Good Morning Scotland programme how the osprey – called Glen – took his unusual route.
At one point it was feared he had died but he has now made it safely to Spain with the help of the two vessels.
Ms Dench – who was seriously injured in a crash which claimed the life of her cameraman in the Highlands last year – explained what happened to Glen after he left the Tweed Valley.
She said he had taken a “particularly unusual route” after his departure on 9 September.
“Around the 11 September, going via a military base and a small pocket of forest, he ended up on the south coast of Cornwall,” she said.
“He headed pretty much over the top of St Michael’s Mount and then we heard nothing from him for about two days.”
The worst situation
Ms Dench admitted that conservationists “feared the worst” for the bird but then, when the signal came back, they found he had taken a “really unusual track” out across the Bay of Biscay.
Glen took a “direct line south” for about 90 miles and then a right angle before heading back towards the UK for about 75 miles.
Ms Dench said her first thought was that he might have been on board a trawler but then realised it fitted with shipping lanes in the area.
“I got in touch with a company called Vesselfinder who mapped it exactly to a couple of very large ships,” she said.
“The first one was one called the Agia Triada, which is a huge container ship.”
He then crossed onto an LPG tanker which was heading in the wrong direction but luckily realised that and made it to a rock on the very tip of Spain before reaching the mainland.
Ms Dench said he had ended up “approximately where he should be”.
“He is currently still in northern Spain and heading for somewhere in West Africa,” she said.