One of the few surviving original blueprints of the Titanic is to be auctioned.
The Titanic sank on its maiden voyage to New York
It was owned by William Wilson, an engineer on the ill-fated Belfast-built liner's maiden voyage.
He got off in Cherbourg to help repair another ship, taking the blueprint with him, and so avoided the 1912 disaster which claimed 1,500 lives.
Specialist auctioneers Henry Aldridge and Son in Wiltshire believe the diagrams could fetch up to £15,000.
The firm's Alan Aldrige said it was the only blueprint in private hands and the only one which included the ship's plumbing.
"There has never been one of these on the market before so it has been a really hard thing to gauge but (it could fetch) £10,000 to 15,000 conservatively but potentially a great deal more," he said.
Mr Wilson's place as the leading draughtsman was taken by replacement Roderick Chisholm who perished in the disaster.
A native of Belfast he worked for Harland and Wolff until 1927 when he joined Royal Mail Lines.
The blueprint was inherited by his daughter, who is putting it up for sale.
The diagram will be coming to Belfast for the Titanic - At Home exhibition at the end of March and will be auctioned in April in Southampton.