麻豆传媒

AND THE KING, he screeched right out like any maid: 鈥淥h my gentlemen, oh my
gallant men!鈥� Charles Kingsley, Westward Ho!

More than five hundred sailors perished when the Mary Rose sank in
July 1545. She had scarcely left Portsmouth harbour when she made a sharp turn
and tipped over. Henry VIII and his courtiers could only watch in horror from
the shore as the sea entered her gun ports. Men and guns slid across her decks,
weighing down her starboard side, and taking her inexorably down to the sea
floor. There she lay, undiscovered for more than 400 years, her port side washed
away and her starboard side buried in silt.

The demise of the Mary Rose left a deep wound in the English psyche.
She was huge for her time: the first Titanic. As the flagship of the Royal
fleet, she had trounced the French and Scots, and had braved Atlantic storms
many times in her career. So why, after almost 35 years of service, did she meet
such a dismal end, sinking like a stone in the undemanding waters of the
Solent?

The wreck was rediscovered in 1971, but it wasn鈥檛 until 1982 that the
Mary Rose could be raised. A massive programme of research followed. As
part of it, tree-ring expert Martin Bridge of University College London and
archaeologist Christopher Dobbs of the Mary Rose Trust have been
studying the preserved timbers. Now they believe they have uncovered a vital
clue to why the ship sank.

The Mary Rose was built between 1509 and 1511. A mighty warship
weighing a full 500 tonnes, she immediately sailed into battle against the
French, near the port of Brest. She attacked the French twice more, capturing
the town of Boulogne, and capably sailed the Atlantic in bad weather. After a
stringent set of timed trials, the organiser wrote an impressive report back to
the King: 鈥淭he Mary Rose, Sir, she is the noblest ship of sail and a
great ship at this hour I trow to be in Christendom. A ship of 100 tons will not
be sooner about than she.鈥�

Heavy load

Great she was, but there was still room for improvements over the years.
Contemporary documents suggest the ship underwent refits in 1528 and 1536. The
documents list the purchase of new and heavier guns and record that her load had
increased to 700 tonnes by the time she sank. What the documents do not say is
how extensive these refits were. Was she repaired or reinforced to cope with the
new load? If she was, were these changes structural? Such changes might well
have involved the introduction of new, untested technology. And that might have
affected her seaworthiness.

Enter Bridge. In 1990 he began using tree rings to date the ship鈥檚 oak
timbers to discover how much of the ship had been rebuilt during her lifetime.
Trees grow a new layer of wood each year and the thickness of these rings
depends mainly on the climate (鈥淩eading the rings鈥� p 40). The resulting pattern
of tree rings is like a fingerprint, telling you when the tree was growing.
Knowing which parts of the ship were rebuilt, and when, may have helped Bridge
and Dobbs find out whether extensive refits were responsible for the final
disaster.

Bridge needed to get his hands on as much wood as possible, without causing
damage to the ship. 鈥淭o tell you the truth, I鈥檇 like to take a chainsaw to her,鈥�
he says. He settled instead for collecting a series of cores, each half a
centimetre across, from some of the key timbers. It wasn鈥檛 easy. At the time,
the ship was being sprayed with fresh water, since conservators were worried
that she might crack up if the old wood dried out. 鈥淚 had water dripping down my
neck,鈥� says Bridge.

And as if that wasn鈥檛 bad enough, it was decided to replace the water spray
with polyethylene glycol (PEG), a wax solution that would gradually replace the
water in the timbers, preserving their integrity. The PEG created even danker
and more slippery working conditions, and there were very few hours in which the
spray could be switched off for Bridge to take his samples.

Still, he persevered, coring away at the timbers that Dobbs suggested. In
particular, Dobbs directed Bridge towards the braces and riders in the ship鈥檚
hull. These are the vertical or diagonal struts that provide structural support.
Made from hefty blocks of wood, they had to come from trees that took years to
grow and therefore have many rings. But these were important because they also
looked like late additions to the ship. Unlike most of the ship, which was held
together by wooden treenails, the braces and riders were fastened onto the hull
by iron bolts鈥攖he easiest way to attach additional timbers.

Back in the lab, Bridge measured the width of each ring on his cores.
Immediately he confirmed what Dobbs had suspected. Some of the braces and riders
showed rings that were laid down after 1511. 鈥淭hese were growing trees at the
time the ship was first built and sailed,鈥� says Bridge. 鈥淭hey are definitely
refit timbers.鈥� Since none of the braces and riders dated from before the ship鈥檚
construction, Dobbs assumes that they were all added together in a strengthening
move at a later date.

By contrast, the beams supporting the main deck were dated to the late 15th
century, several years before the ship was built. This doesn鈥檛 prove the timbers
are part of the original ship, as tree-ring dating gives at best the felling
date of the timber鈥攏ot the date it was used in construction. But documents
from the time suggest that delays were minimal between felling and construction,
probably because wood is best worked while it is still green with sap.

But one main deck beam, dated by Bridge to 1535, was certainly not original.
Dobbs thinks this beam was replaced in a one-off repair. 鈥淢ost of the main deck
beams are aligned with the deck beams below,鈥� he says, 鈥渂ut when I went back and
had another look, I noticed this one was about a foot out.鈥� This would not
affect the seaworthiness of the ship, but it does show that substantial repairs
took place just a few years before the ship sank. 鈥淭hey would have had to take
out decking and some of the internal planking in order to get a big beam like
that into the ship,鈥� says Dobbs. 鈥淚t鈥檚 a major job.鈥� What鈥檚 more, Bridge found
that large L-shaped deck supports at the stern all dated to the 1520s. It was
the first suggestion that the stern of the ship had been rebuilt.

These changes didn鈥檛 come as too much of a surprise, because historians knew
the ship must have been strengthened during her career. But uncovering the
details gave Dobbs and Bridge confidence that they were on the right track. Now
they needed to go further, to see if they could cast light on the reason for the
sinking.

And they have done just that. In the past month Bridge has found a vital clue
to the ship鈥檚 sad end. The final ring from a timber in the ship鈥檚 hull
(see Diagram) dates to 1540.
This is an unmistakable five rings beyond the fecund
summer of 1535 (鈥淩eading the rings鈥�). Peering down a microscope at the edge of
the last ring, Bridge thinks he can see signs of some new growth snapped off in
its prime. It鈥檚 the new wood of 1541. There鈥檚 no bark on this
timber鈥攑erhaps the shipwright鈥檚 axe severed off bark and some of the outer
rings too. But Bridge has a pretty conclusive upper limit on its felling date.
By the summer of 1545, this timber was out of the forest and sinking fast.

This discovery is crucial, because of the position of the timber. All of the
ship鈥檚 planking is built around a wooden frame which is the ship鈥檚 skeleton,
providing shape and strength. The 1541 timber is part of the frame. Structurally
speaking, it鈥檚 about as important as you can get.

To replace a part of the frame, either the surrounding outer planking had to
be stripped off or the nearby internal planking, the secondary riders and the
decks had to be removed. Either way, it鈥檚 a big task which would have taken many
months. The Mary Rose might have been a familiar favourite on the day
she sank, but her hull was not well tried and tested, especially with full
battle gear on board.

And that raises the question of the gun ports. Water poured into them just
before the Mary Rose sank. But why? The ports were designed to be
watertight, but the sailors had left them open. Bridge and Dobbs suggest this
may not have been a simple mistake.

They point out that the gun ports closest to the waterline may have been a
recent addition to the ship. The top of the replaced frame comes right up to one
of the lowest gun ports
(see Diagram), suggesting that this and the other low
ports were added, along with the new guns, in the 1530s and 1540s.FIG-mg22514501.JPG

Why should this matter? Well, it could mean that the crew was used to being
able to turn the ship without closing the gun ports. The ports towards the back
of the main deck and those on the upper decks are well clear of the waterline,
and it would probably make no difference if they were left open. The lowest
ports, on the other hand, could be much more dangerous.

There is plenty more work to do. Dobbs and Bridge are now dating additional
timbers around the lowest gun ports, to see if they really were new when the
ship sank. But they believe they have established that the Mary Rose
was no old hack. Following substantial refits, she was a brave new ship sailing
on the cutting edge of technology. And for all Titanics, ancient or modern,
that鈥檚 rarely a good idea.

In Spring, oak trees lay down large hollow tube-like cells called vessels. In
Summer they lay down denser wood. The two layers together form a whole ring,
representing a year of growth. The summer wood is laid at a rate that depends on
the weather: a warm, wet summer will give a wide ring; a hot, dry summer a
narrow ring. So the width of the rings provides an annual record of climate at
the time the tree was growing.

Dendrochronologists have put together an impressive database of English oak
chronologies stretching back thousands of years. Every tree has its own history,
but instances of extreme weather, like the wet summer of 1958 and the hot, dry
summer of 1976, are common to almost all trees in northern Europe. Given a
climate record spanning at least 60 years, you get enough of a pattern of wide
and narrow rings to be able to match the timber to the database.

Another thing a dendrochronologist looks for is sapwood. Sap rings are those
immediately beneath the bark which were still alive when the tree was felled.
They can be identified in timber by their pale colour and propensity to
woodworm. Because of this a shipwright will often remove the sapwood and bark
before using a timber. There can be anywhere between 5 and 95 sap rings on a
living tree, so a piece of timber without any sapwood must have been felled a
few years after the date indicated by its oldest ring.