Efforts have admitted that a 15-year bid to preserve Britain's largest surviving prehistoric logboat has failed.
Carved from a huge oak tree, the six-tonne Hasholme Boat was found by archaeologists in a former inlet of the Humber estuary near Holme on Spalding Moor in 1984.
Natural materials in the water-logged silty clay where it was discovered helped preserve the timbers.
Thought to be around 2,300-years-old, the boat was initially taken to the National Maritime Museum in Greenwich for detailed recording and analysis.
It was later relocated to the Hull and East Riding Museum in High Street, Hull, and placed in a specially-designed chamber.
Since then, the boat has been constantly sprayed with a special type of chemical wax in order to preserve it.
Experts have to wear special protective clothing to enter the chamber.
But now officials have conceded the intensive, but expensive, technique is no longer viable.
They also say the vessel has actually suffered some deterioration as a result of the wax spraying.
Leaks in the chamber and health and safety concerns over the spray system led to it being shut down last December.
A subsequent review of the project has led to a decision to switch to a new air-drying preservation method instead.
Simon Green, assistant head of culture and lifestyle at Hull City Council, said the problems encountered with the Hasholme Boat mirrored those found using the same preservation method on the Henry VIII's flagship the Mary Rose, the country's best-known maritime wreck.
He said: "We have worked closely with the specialists in the field of waterlogged timber preservation from the York Archaeological Trust.
"It's fair to say that the original aims of the preservation work have not been achieved because the preservation has taken far longer than anyone anticipated.
"But it's also worth pointing out that no-one really knew if the treatment would work when it was started back in the 1980s."
Mr Green said air-drying the vessel in its existing chamber carried the risk of some of the wood cracking and splitting.
But he added: "Air-drying will allow people to see the boat in detail for the first time because it has been cloaked in spray and mist since it first arrived here.
"It also gives us the opportunity to look at how we can improve the display and some the interpretation features around it."
Source: This is Hull and East Riding [October 14, 2010]
