The Big Question: Can the 'Cutty Sark' be rebuilt, and would it still be the same ship?

Why are we asking this question now?

The Cutty Sark - the world's most famous clipper ship - was badly damaged following a fire that broke out early on Monday morning. The fire burned for an hour and a half before it was brought under control. During that time the main deck and the 'tween deck were completely destroyed with some 30 tons of timber going up in smoke. Some of the ship's ironwork is thought to have buckled as a result of the intense heat, but as yet a detailed study of the extent of the damage by specialists at the Cutty Sark Trust has had to wait pending a police investigation. The site has been designated a crime scene because of suspicions that the fire may have been arson.

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What would be the main obstacle to rebuilding the 'Cutty Sark'?

One of the unique features of the Cutty Sark was its composite structure, meaning that it was a mixture of iron and wood. It was built with a special iron framing sandwiched between the outer and inner timbers of its hull. It was further strengthened by iron cross supports for the timber beams carrying the wooden decks.

If the iron "frames" - the ribs of the ship's hull - have been badly buckled or damaged in the fire then restoration would prove exceptionally difficult and costly. But it would not necessarily be impossible, according to Fred Hocker, director of Vassa Research for the National Maritime Museums in Stockholm. "Wood can always be replaced, but if the ironwork is badly damaged, that is another matter," said Dr Hocker, an experienced shipwright who specialises in the rebuilding of old wooden sailing ships. "The ironwork is in many ways the soul of the Cutty Sark."

How much of the 'Cutty Sark' was lost?

Fortunately, at the time the fire broke out more than half of the ship had been removed for a £25m renovation programme. The masts, rigging, coach and deck houses, the master salon, significant amounts of planking, the jolly boats and other such removable items had all been put into safe storage. So the damage was largely confined to the ship's hull and its timber decking. Eric Kentley, curator of the Cutty Sark Trust, said yesterday that a visual inspection clearly shows that the main deck and 'tween deck have been totally destroyed. Burning debris had also fallen to the bottom of the hull during the fire but as yet it was not clear how much further damage has been done to this part of the ship.

Apart from the fear of heat damage to the iron frames, the other concern is that the loss of weight caused by the destruction of the heavy timbers on the decks may lead to further twisting of the ironwork, which has always supported the many tons of wood resting above it. The first task is to assess the extent of the damage to the ironwork.

Can the timbers be replaced?

The Cutty Sark was mostly made out of teak, a tropical hardwood that is now in very short supply, certainly in the sizes and amounts needed for replacement. The main deck was in fact scheduled to be replaced anyway because it "leaked like a sieve" according to Mr Kentley. The trust had already secured some 19th-century teak from a large house in India that was being demolished. "Luckily they were not in the ship yesterday. They are worth about £400,000," Mr Kentley said.

Some of the damaged or destroyed teak planks in the Cutty Sark are so large that they cannot be replaced with the same wood - such large trees are rare because most have been cut down. Another tropical hardwood timber, such as iroko, would have to be considered. But this would lead to the difficulty of mixing two kinds of wood with possibly different physical properties, such as expanding at different rates under varying conditions of heat and humidity.

If big enough beams or supports cannot be found in teak, it may be possible to glue pieces of timber together as a laminated structure, according to Dr Hocker. "Glues today are pretty good and the joints can be made so you don't really see them," he said.

If all else fails, it may even be possible to use plastic supports under the decks where they cannot be seen, which are being considered for the Vasa, a 17th-century warship restored in Stockholm harbour. However, it is highly unlikely that the Cutty Sark Trust would ever agree to that.

Would a rebuilt 'Cutty Sark' still be the same ship?

This goes to the heart of a philosophical riddle known as Theseus's paradox: at what point does an object that has had all its components replaced remain the same object? The name comes from the ship which carried Theseus back to ancient Athens. The ship was preserved but had its oars and other parts progressively replaced, causing Greek philosophers to argue about whether it remained the same ship.

According to Dr Hocker, all timber sailing ships would have had many if not most of their parts replaced during the course of their working lives. This is even more true when ships are restored to their "former glory". He doubts for instance whether more than 5 per cent of the HMS Victory docked in Portsmouth saw the Battle of Trafalgar. From his point of view, therefore, a restored Cutty Sark with modern timber would still be the Cutty Sark.

However, Mr Kentley emphasised that the trust's philosophy is conservation rather than rebuilding. In other words if a damaged timber can be restored in some way rather than replaced, this is the preferred option even if there is an aesthetic trade-off - scorch marks for instance. "Our view is that we need to maintain the fabric of the ship. Otherwise we get a replica by stealth," he said.

Are there any silver linings to this dark cloud?

The one good thing about an iron-framed ship is that its timbers are mostly straight beams and planks. Other old wooden ships have curved timbers, which have to be specially selected from the curved branches and trunks of growing trees - and these are in far shorter supply than they once were.

Another aspect of the fire is that it will reveal parts of the ship's framework and skeleton that have never been seen before so it could provide shipwrights with an unrivalled opportunity to investigate and dissect how the Cutty Sark was put together. A final blessing in disguise is that the tragedy could provide the sort of publicity impetus needed to collect the many millions of pounds now needed to restore the ship fully so that it remains the most famous clipper ship in existence.

So will a rebuilt 'Cutty Sark' simply amount to a replica?

Yes...

* The main deck and 'tween deck have been totally destroyed and will have to be replaced

* Some of the ironwork is probably damaged and will have to be removed

* The fire marks the end of the Cutty Sark's long journey and it should now rest in peace

No...

* All sailing ships underwent continual repairs in the course of their working lives

* The iron 'soul' of the ship - its metal frame - will still be largely intact

* More than half of the ship was totally unaffected by the fire, and many important parts were in storage at the time