Volunteers preserving Scotland's last surviving lightship have said plans to sell the vessel are "scandalous".
The Maritime Volunteer Service (MVS) is considering getting rid of the North Carr, which is based in Dundee, because future repairs could be costly.
However, the Tay branch of the charity, which has been looking after the vessel, which was built in 1931, said it was not consulted about the sale.
Lightships were used instead of lighthouses to warn sailors of dangers.
The North Carr was built in Glasgow and launched in 1933.
It was in service off Fife Ness until 1975, apart from a brief period during WWII when she was stationed at the entrance of the Clyde.
She then became a floating museum in Anstruther, Fife, and was later moved to Dundee.
Bob Richmond, the head of the MVS Tay Unit, said: "It's an iconic vessel and has a great history to the local area, so we were absolutely appalled when this decision appears to have been made to dispose of it without reference to us.
"The North Carr lightship is the only surviving vessel of its type and the only vessel in the UK, if not the world, that still has all her original equipment on board. She's on the national historic ships register.
"She's very unusual because most lightships when they've been retired or scrapped have been converted into restaurants, offices, sailing ships, discos, that sort of thing.
"But this lightship miraculously survived absolutely intact, exactly as she was when she was decommissioned in 1975."
The volunteers are particularly angered by the fact the sale could go through just as the 50th anniversary of the Mona lifeboat disaster is commemorated.
On 8 December 1959, an anchor cable of the North Carr snapped during a storm and she began to drift.
The Mona lifeboat was called out from Broughty Ferry with eight men on board. She never reached the North Carr and all the lifeboatmen lost their lives.
"It's absolutely ridiculous when there's all these sensitivities running around during this anniversary and I just hope that the local community do not throw any blame at my local group," Mr Richmond said.
"This is a London-based decision for a very Scottish vessel, that they have never even been up to see."
However, the MVS said it hoped to come to an arrangement with any future buyer that would allow the local branch to continue using the vessel as its base.
National Secretary Haydn Chappell said: "It's an ageing vessel, it will require money spent on it in the near future.
"We are exploring options, no decision has been taken, we are looking to see if any other local group are interested in taking on the vessel.
"We're not a vessel preservation society, we don't have the skills, or the time, and certainly not the money.
"We're focusing on active vessels that go to sea and train people."