Tim Kirk’s Shipwright’s report for March

As we continue the behind-the-scenes planning to return to working in the Longshed we have, at last, been able to commence preparatory work on the timbers for the backbone of the ship.

Some time ago we took the decision to saw blanks for the keel and posts (from the logs that were delivered in January).  We have made up a ladder to guide the first cut of the chainsaw mill, to avoid wasting the valuable resource that these logs represent.

ladder for the chainsaw mill

The keel log will be cut at the beginning of April and transported to the Longshed so that it can be shaped and finished with axes.

The curved log for the ‘underloute’ and lower stems will get the same treatment.  Fitting patterns from the lofting that we did earlier shows that this log is as near a perfect fit as could be wished for.

When all these parts are in the Longshed we will truly be able to say that the actual build of the ship has begun.

Tim Kirk March 2021

The Other Team on “The Dig” – Joe Startin

The film “The Dig” understandably focuses on the team Charles Phillips put together to handle the burial chamber and its contents.  It omits the team he organised to survey the ship.

Phillips first met Mrs Pretty, at Sutton Hoo, on 6 June 1939.  He made phone calls on her behalf to the British Museum and to the government (the Office of Works) that day.  The government formally asked him to take over the excavation project at the end of June.

The survey team was led by Lieut-Commander J K D Hutchinson, aged 38, married with no children, the Keeper of the Department of Ship Models at the Science Museum and a retired naval officer.  His second, also from the museum, was A S Crosley, aged 45 or 46, with (from research by Dr Caryl Dane) at least three daughters up to the age of 10.  Crosley was an active member of the Newcomen Society and presented a paper about the ship to them in 1943.  The other member of the team was young Frank Gillman.

Hutchinson first visited the excavation site at Sutton Hoo on 12 July 1939,  the day before serious work began on the burial chamber.  After an inspection, he explained to Mrs Pretty what a survey of the ship would require, and she agreed to his proposals.  On the afternoon of Tuesday 8 August the team of three arrived and “…..orders were given in Woodbridge for the construction of the necessary wooden apparatus for the survey”.  This was one week after the work on the burial chamber had finished.

Mercie Lack and Barbara Wagstaff also arrived on 8 August. They were on holiday in the area.  Schoolmistresses and companions, they were very capable photographers with good equipment.  They made an invaluable record, and were among the last excavators to leave, on 25 August.

In his Newcomen Society paper, Crosley describes how the survey team measured the positions of certain rivets  near each rib, relative to a datum line with plumb bobs hanging from it.  This was a laborious three-man operation.  Where that approach was not practicable, at the bow and stern, measurements and sketches were made from a bosun’s chair suspended above the excavation.  Southampton University used this data as the basis of research to derive the plan that SHSC are using to reconstruct the Ship.

Hutchinson and Phillips seem to have got on well.  Hutchinson took charge of most of the work at the site, while Phillips “was able to consider the problems of the ship at leisure and discuss them with Commander Hutchinson”.  

They pursued a number of investigations together – into the keel, for example, and how it connected to the stem and sternpost.

Hutchinson’s signature can be seen on the legend for a tracing of the 1939 ‘provisional drawing’ done by Crosley – which can be seen in Ipswich Museum

Hutchinson died ‘of illness’ in July 1944.  He was Acting Commander of HMS President, which I believe was a training establishment on the lower Thames.  All his papers were burnt by his widow.

It was said that Crosley and Gillman did not like him.  Perhaps he was a hidebound officer who rather stood on ceremony.  At the end of his paper, Crosley says: “I thank the Director of the Science Museum for having allowed me to undertake this interesting survey and for permission to publish the results.  In making the survey I would like to put on record the valuable help given by my colleagues, Messrs. Gillman and [John] Jacob, who showed untiring energy under difficult conditions.”   There is a notable omission…

Joe Startin

 

 

An Experience of Photogrammetry by Andy Spencer

It is important for SHSC to have a scientific record of the components of the ship, as part of our experimental archaeology programme.  As things progress, we need to be able to look back at the materials we used and what we did. Photogrammetry is the science of creating a three dimensional model from a series of standard two dimensional photographs.  It is clearly the right thing for us to do.

What I have learned so far is that photogrammetry can be tricky!

I was already involved in The Ship’s Company as a volunteer, and as someone with an interest in photography starting off the photogrammetry project played to my strengths.  In an initial meeting a group of interested volunteers discussed the use of photogrammetry to create 3D models of the ship, its parts and the tools we would use in constructing it.  Subsequently we were kindly given access (by Felix Pedrotti of Southampton University) to some online tutorials  about using software and how to upload and convert the images into a 3D model.  I also did some research online and contacted Julian Whitewright for advice (there is a profile of Julian in the February 2021 newsletter).

Most people would choose to start with something relatively small that could be photographed under ideal conditions – like the clamp shown at the top of this post. However, we decided that the first photogrammetry project for the SHSC records should be the log that will form the keel of the ship. The keel log is 13 metres long and currently stored in a poorly lit barn.  Our project was no small task!

In January, fellow volunteer David Keeble and I made our first attempt to record the keel log and a second log that will be used for the stem and stern.  We had to decide on the section to be covered in each picture, and on how many to take down the length of the whole log.  There would need to be a large enough overlap in each picture so that the software creating the 3D image can work out how each picture sits in relation to the next – and from that build a 3D model.  Clever software!

We marked out locations about a metre apart with white tape down the length of each log , and about the same distance from the sides. We decided that three photographs would be needed at each location: close to the floor, about 75cm above the floor and looking down onto the log as close to vertically as possible.

The image below shows the plan that I sent Julian for advice on the angles we needed to cover.

On Julian’s advice we set more locations for pictures to be taken from each end of the log that would help the software interpret the images.  So we marked 36 locations around each log and took three pictures from each one, starting off at the lower level and then going round the entire log again at the second and third heights.

The right levels of light are important so it was challenging at times – low light levels meant long exposures and in places we had to use extra lighting but too bright a light also causes problems. We ended up with 216 carefully taken photographs!

We sent all the images of to Julian to upload using the Agisoft computer programme at Southampton University.  But after all the our efforts the software couldn’t create a 3D model.  We needed even more pictures, especially at the ends and from the top.

So, we are going back to try again with more lights.  I will fix the lens on the camera so that the zoom doesn’t change and we will need to work out the maximum possible distance that we can get from the trunk where space is limited.  Hopefully second time lucky!

The photo below and video link show how well the technique can work.

Andy Spencer

R2 D2, an exercise in photogrammetry by David Matzliach

Joe Startin Speculates, ‘Did the Sutton Hoo Ship Sail?’ (Part 4)

This is the fourth in Joe’s series of speculative posts – click here for links to parts 1, 2 and 3  

Edwin Gifford built a half-length replica of the Sutton Hoo ship in 1993 – Sæ Wylfing (moored outside the Longshed in the photo above).  He was fed up with people saying that the shape of the hull meant that it could not sail in much the same way as the classic Viking ships.

He was not seeking authenticity in materials, building techniques, and so on, but he did take care over the shape of the hull. The weight of Sæ Wylfing is 675 kg. Crudely, you would then expect the full-size ship to weigh 2 x 2 x 2 = 8 times this, or nearly five and a half tonnes. The hull and the ribs of the reconstructed ship are indeed expected to come close to this, but the thwarts, other internal supports, and a deck will add further weight.  Actually we are expecting it to weigh in at about 9 tonnes.

And of course he rigged a mast, and a yard and a sail to go up it.

Gifford gave the central thwart a thicker support in the middle, and some reinforcement where the front of the mast pushed against it.  In the image below, down between the oars you can see a lengthways member, with a recess in it. This is called a keelson, and the hole is a mast step, where the bottom of the mast fits. The main force the mast exerts on the hull is downwards, and the job of the keelson is to distribute this.

Gifford recounts some of the adventures he had in Sae Wylfing between 1993 and 1995. All the pictures show him at the helm, and I suspect this was always the case. He made some small additions to the keel in the winter of 1993/4. In 1994, when he was double-reefed in a wind gusting to 22 knots, he found he could make no progress to windward. He “decided to lower mast, first time afloat, and row.” This must have been terrifying. The dedication and composure of his crew was admirable.

His best result sailing to windward was at the Maldon Festival in 1995.

“…we covered three nautical miles direct to windward in 3.5 hours, despite many short tacks and loss of ground in crowded anchorages.”

This is just under one knot for ‘course made good’. For a land lubber that’s about one mile an hour.  And the effort of enforced tacks would have been a huge task for the crew.

The full-size reconstructed ship will be eight times as big as Sae Wylfing….Rowing (and paddling) it will be our priority. The first trials will be on the Deben; then the time will come to cross the bar and go out to sea.

Sae Wylfing on the Deben 2019

When the trials in a seaway are complete, and the ship is much better understood, we can explore how the hull performs with a big sail and the wind from the side.

Joe Startin

Tim Kirk’s Shipwright’s Report for February

This month progress on the build has been very limited because of lockdown restrictions.  This report is about essential work that we are doing to source wood for the hull, frame and oars that will make the ship a strong, seaworthy vessel.

Readers of previous posts will know that we already have already obtained a straight grained oak log for the keel and another fine one to begin forming the curved ends of the ship.  Most of the rest of the timber needed for the hull is in two forms:

  • long clear runs of oak from trunks 6 metres to 9 metres in length and up to 1.2 metres diameter for planking and other longitudinal timbers, and
  • curved timbers up to 4 metres long and 0.4 metres diameters for frames or ribs

We will also need multiple smaller sections.

Oak for planking and longitudinal members must be straight-grained and clear of knots, shakes and other defects.   The twist in planks from trees that have grown with twisted grain (shown by spiralling of the bark fissures around the trunk) is not acceptable for constructing most of the ship.  But we do need just one length of timber with a twisted grain, about 6 metres long and 0.9 metres in diameter for the end pieces of the lower planks.

Twisted grain in a cleaved log

The framing of the ship is built up from multiple pieces of curved timber:

  • floors, which cross the centreline and provide much of the transverse strength
  • futtocks, which attach to the floors and frame sides of the ship; and
  • rongs, which combine a floor and a futtock.

Combinations of these frame sections, regularly interspersed along the length of the ship, minimise the weaknesses caused by scarfed joints and maximise the athwartship strength.

These timbers, made from curved trunks, or larger branches from the lower canopy of the tree, need to be up to 3 metres long and 0.5 metres diameter.  For strength, ideally we need to avoid using the central ‘pith’ and the outer ‘sapwood’.  However, there is some archaeological evidence from other ships that both the centre of branches and sapwood might sometimes have been used.

The key requirement to maximise strength is that the curvature of the grain in the frames meets the natural curve of the ship. This means that we have to place individual full-size patterns against the timber that we are planning to use to assess whether it is suitable.

The photo on the left below shows a frame section fitted to our full-scale model of the ship.  The softwood molds in the background are temporary. The drawing on the right shows the different frame sections and their placement within the ship.

We need larger curved sections to form the stem and the sternpost .  We already have one suitable trunk but we will need at least one more – up to 6 metres long.  The trunk in the photos below (shown standing and felled|) is 10.8 metres long and 0.9 metres diameter – big enough to obtain two pieces, one from either half of each length of timber.

We have made full-size patterns to test against potentially suitable trees.  We hope to find a group of suitable trees on one site as this would save time and reduce the costs of transport.

Other, smaller curved pieces will come from smaller branches in tree canopies.  This sort of timber isn’t easy to obtain as it is not commercial for timber yards and is often cut up for firewood.  The photo on the left below shows grown a ‘crook’ , needed for the end frames of the ship, and on the right a branch junction that will be used for making ‘tholes’ (where the oars pivot on the gunwale of the ship).

We need about fifty sections like these – each about 1.2 metres long and 0.3 metres diameter.

Oars – we will need about sixty in total, including spares and different experimental designs.  Although tholes (primitive rowlocks) were identifiable in the Sutton Hoo Ship excavations there was no evidence of oars. We have found out as much as possible about what the original oars might have looked like but there is a lot to be done on shape, weight and pivot points. This is a case where experimental archaeology comes into its own – all these issues will be covered in detail in a future research paper.

Initially we will trial different materials – oak, ash and scots pine – making about six of each type. The timber for oars needs to be straight sections about 6 metres by 0.2 metres with no knots or other defects.  Larger diameter timber could be used to make several oars from each trunk. Once we make a final decision on what sort of trees to use we will need enough wood for forty oars.

Other parts of the ship will come from offcuts of the larger sections.

We expect to use the equivalent of around twelve mature oak trees to build the ship.  Although this will undoubtedly require more than twelve trees to be felled one of our key targets is to replace each tree we use with ten saplings.

Tim Kirk, Master Shipwright

 

 

Arrival of our keel log!

It’s here.  We have a the keel log we have been waiting for!

What a story of suspense, from first identifying the tree in a Forestry England site in Wiltshire nearly a year ago, through delays in felling, postponements because of Covid, a carrier who failed to bring back the goods, to finally manoeuvring the artic into the shed and then craning off the logs.

The log – or logs, for as well as the straight part of the keel we have the curved one for the two ends of the ship – are now safely ensconced in a barn near Woodbridge where the team will be able, soon, to do preparatory work before we bring them to the Longshed, hopefully to great fanfares.  Even without fanfares, the arrival at the barn was really quite special.  A huge articulated truck complete with (very necessary) accommodation in the cab rolled up one damp chilly January morning, into a giant barn.

Brian Amos, the driver, had been on the road the day before and spent the night in a lay by south of Woodbridge. He demonstrated great skill in manipulating the huge logs off the trailer; the barn owner observed that at one point the apex of the crane was within 15cm of the barn roof but both logs were quickly manoeuvred with pin point precision onto the waiting supports.

 

This was an occasion where practicality ruled out any attempt at Anglo-Saxon authenticity! Perhaps their log movements would have been more like the description of a nineteenth century timber delivery in this extract from Thomas Hardy’s The Woodlanders

The proud trunks were taken up from the silent spot which had known them through the buddings and sheddings of their growth for the foregoing hundred years; chained down like slaves to a heavy timber carriage with enormous red wheels, and four of the most powerful of Melbury’s horses were harnessed in front to draw them.

The horses wore their bells that day.  There were sixteen to the team, carried on a frame above each animal’s shoulders, and tuned to scale, so as to form two octaves, running from the highest note on the right or off-side of the leader to the lowest on the left or near-side of the shaft-horse.  Melbury was among the last to retain horse-bells in that neighbourhood; for, living at Little Hintock, where the lanes yet remained as narrow as before the days of turnpike roads, these sound-signals were still as useful to him and his neighbours as they had ever been in former times.  Much backing was saved in the course of a year by the warning notes they cast ahead; moreover, the tones of all the teams in the district being known to the carters of each, they could tell a long way off on a dark night whether they were about to encounter friends or strangers.

Philip Leech

What on earth is experimental archaeology?

In the Ship’s Company we often calmly say that “our project to re-create the Sutton Hoo Mound One Ship is the biggest experimental archaeology project in the UK/Europe/the northern hemisphere/the world” just depending on how modest we are feeling.  But what are we talking about when we say that?

Many of you will know that as well as being a current Director of the Ship’s Company and Director of the third Sutton Hoo excavation, Professor Martin Carver is just a brilliant communicator.  And, admittedly, it was off the cuff in an unscripted interview for one of the SHSC films, but he has also given the most succinct definition of experimental archaeology that I have heard.  Martin said “we try things out to see if they work”.

A lot is implied in that simple statement.  Coates et al in the paper Experimental Boat and Ship Archaeology: Principles and Methods, state “….to learn more from [excavations] than is immediately obvious ….it is necessary to formulate hypotheses about past technologies, artefacts and cultures…. In Maritime Archaeology such experiments can take the form of building, on a full or reduced scale, models, or making other simulations of ancient boats or ships and testing them in repeatable sea trials, real or simulated.”  

We have to try to build what the archaeologists found.  We can’t diverge from that – except where the data is flaky or for example the resulting boat wouldn’t float, or wouldn’t float the right way up.  And we need to have clear aims, that might be, as Professor Sean McGrail suggested  “to use authentic methods and materials to establish how an ancient craft was built and to estimate performance”. (Experimental boat archaeology some methodological considerations 1986)

That is what we are trying our best to achieve.  Of course the Anglo-Saxons didn’t build their vessels under electric light in a shed with a smooth concrete floor – and a dry shed with a hard floor is not always an advantage when working green oak with axes!

The photos below show examples of some of the tools that we are using – tools that would have been available to the Anglo-Saxons when they built the original ship.

For our project, what both saves us from blind alleys – but causes a lot of discussion in planning – is the incompleteness of the data.  The Ship cannot be re-excavated and we inevitably have to interpret the data in what is a limited record.

Digital image of the ship based on the record of where rivets were found in the original excavation – the colours indicate differing levels of certainty – black highest and blue lowest.

But we do have clear aims, stated superbly and succinctly later on in Martin’s interview:

“The construction is to be undertaken with the utmost circumspection and attention to detail.  Every action taken that relates to the materials, their assembly, and their adjustment in the ship’s structure is to be recorded so that a trail can be followed to and from every decision made by the shipwright and their advisors.

While no-one can today build an accurate representation of an ancient vessel, we propose to build an experimental craft informed by as much archeological information, previous experience, and science as we can muster.”

The data that we acquire about the implications and consequences of building such a large ship, and the feasibility of its performance on river, sea, and land [hauling between rivers] will move the collective knowledge on Anlgo-Saxon sea-faring from a level of weak generalisation to a new platform of likelihood.”

That is our grand aim.

.Philip Leech

Shipwright’s report – January 2021 – Tim Kirk

Unfortunately, lockdown has again slowed our progress.  However with the arrival of two logs for the backbone we are in a good position finally to begin the build of the Ship as restrictions ease.

We have lofted (drawn full scale) the stem and stern posts which will enable new patterns to be taken for the underlouts (between the main keel and stem/stern).  The sections of the stem and sternpost and the logs for the keel can be rough sawn before delivery into the Longshed for final finishing.  At present, we aim to complete the stem and stern posts in two pieces – as shown in the photo below of the model that I made.

Image showing detached upper sternpost and lower sternpost attached to underlout

Because of the size of the posts (some 6m long and 300mm square in section before shaping) it isn’t easy to find exact curves on a log of suitable quality.

Hopefully this will all happen around Easter time.  In the meantime, stay safe and sharpen your axes.

Tim Kirk

News from the Director of the Institute for Digital Archaeology – Roger Michel

Our partnership with the SHSC continues to provide us with a steady stream of interesting and exciting work – and great opportunities for other helpful partnerships.

Our efforts in the laboratory examining rivets (courtesy of the National Trust and Sutton Hoo Society) from the 1939 dig have yielded some extraordinary results.  I won’t pre-empt my colleagues by revealing too much.  I will only say that in addition to learning more about where, when and how the rivets were produced (and how we might produce rivets of our own using traditional materials and techniques), we may also have an unexpected opportunity to uncover some very specific data about the wood used to construct the ship. Please stay tuned for more information on these important topics.

On other fronts, an unexpected collaboration has emerged over the past six months in connection with the America’s Cup races to be held in New Zealand this spring.  During the last America’s Cup in Bermuda in 2017, the IDA sponsored a regatta featuring traditional Bermudian watercraft: 25 foot pilot gigs.  It was a great day on the water and – at least in my view – a welcome diversion from the very non-traditional sight of 5mm-thick plastic boats with trick sails skimming across the waters of the Great Sound.

Racing a Bermudan Gig 2017

Flash forward 3 years.  During a wide-ranging hour long interview with Radio New Zealand over the summer on a museum initiative with Oxford, our conversation somehow turned to a Maori translation of Beowulf that I had produced in 2012. From there it was a short hop to a lengthy discussion of the Sutton Hoo reconstruction project – and the many startling parallels between the ancient sea-faring cultures of New Zealand and Britain.  Without thinking too much about the consequences, I suggested that a race between an Anglo-Saxon longboat and a waka might be an appropriate sequel to the gig races of 2017.  Suffice it to say, people in New Zealand were listening.  Offers of technical – and political – support streamed in and now it appears that a waka versus longboat may well be on the America’s Cup 2021 undercard. You can hear the original interview by clicking the link to Roger Michel Radio interview on NZ interview

Although the competition boat would be a locally sourced simulation of a clinker-built Anglo-Saxon warship, the event would provide an excellent opportunity to educate visitors about the Sutton Hoo project – and northern European boatbuilding history generally.  It would also provide us with a chance to attract allies to the SHSC project from among a strongly boat-focused population.  Again, stay tuned.

Finally, yet another potential collaboration has emerged from an unexpected source.  My Oxford contemporary, historian Charles Spencer, has written an extraordinary new book on the White Ship disaster of 1120.  A best-seller right out of the gate, Earl Spencer’s careful chronicle of one of the most tumultuous periods in English medieval history provides a wealth of information about the clinker-built Viking-style boat that lies at the heart of that infamous episode. We expect to learn even more about the White Ship’s construction during a series of recovery dives at the wreck site this spring and summer.  The area has never been subject to any professional archaeological examination, and so may yield interesting new clues about the structure, composition and cargo of the doomed ship.

Given the many physical similarities between the White Ship and the Sutton Hoo Ship, and given also the vastly better surviving information about the architecture and construction of the White Ship as compared to the earlier vessel, examination and study of the former may well help to resolve some of the persistent mysteries surrounding the latter – including possibly providing clues about the Sutton Hoo Ship’s method of propulsion and helping to determine whether it was modified when pressed into service as a burial ship.

Certainly there are differences between the two vessels – the White Ship was a little larger and the upper strakes were pierced for oars instead of being equipped with tholes like our ship.  However the similarities swamp the differences.

Image of the White Ship disaster

In anticipation of the wreck dives to come, Lord Spencer said “I look forward to discovering possible connections between these two historic British ships.” He added that he “hope[s] that learning more about the construction of the White Ship will provide some helpful insights into medieval boatbuilding practices generally.”  

Personally, I am looking forward to a summer of exciting discoveries with Lord Spencer – and bringing to bear what we learn on the beautiful ship that will be starting to emerge day by day in the Longshed.

Perhaps a reconstruction of the White Ship, as well, may be on the cards. Time will tell.

 

Joe Startin speculates – Did she sail? Part 3

Sae Wylfing - the half length replica of the Sutton Hoo Ship

Opinions about whether or not the Sutton Hoo ship sailed differ between sailors and non-sailors.  It is difficult for the sailors, whatever their views, to avoid patronising the non-sailors.  Only practised sailors, they will suggest, can understand such things as: the forces on the mast, the stays, the shrouds and the rudder; the significance of a keel, leeway and ‘weather-helm’; the fore and aft position of the mast; the usefulness of being able to sail just that bit closer to the wind; and so forth.

With a following wind , the ship can easily move forward in response.  It can quickly get up to speed without large forces on the rig.  The ship is designed to move in that direction, with the minimum drag from the water.  Once moving with the wind, the force on the sail will diminish, and there will be even less strain on the rig.

When the wind is from the side, the forces on the rig are much greater.  The ship presents a long side to the water, and naturally resists being pushed sideways.  The windward shrouds – the lines from the windward side of the hull to the upper parts of the mast – tighten.  The large force from the wind makes the ship heel.

The effect can be seen in this picture of a modern yacht.

A sailing boat heads towards the lighthouse at the end of the Needles rocks on the Isle of Wight, Hampshire, UK.

The sideways movement of the hull is resisted by a reaction force from the water.  These two large forces, from the wind and from the water, largely oppose each other.  They strain the ship internally, but for the ship as a whole they largely cancel out.  There remains a small net force that moves the ship forwards.

The rig imposes forces on the hull.  One end of each windward shroud is trying to tear itself away from the ship’s side; the other end is pulling the top of the mast downwards, resulting in a large compressive force through the mast into the bottom of the hull.

For the reconstructed Sutton Hoo ship to withstand such forces, the hull would have to be strengthened, and the downwards point force from the bottom of the mast would have to be distributed.  We have no clues from the 1939 remains how this might have been done in the original ship, if it was done at all.  The bottom of the central part of the ship was obliterated by the burial chamber, no fittings for shrouds or stays were seen, and none of the thwarts or their supports were found.

Sutton Hoo ship plan of mid-ships section looking forwards

Some people used to say the ship could not sail because she would just skid sideways over the water.  There is no keel to ‘grip’ the water.  But the side of the hull does offer a lot of resistance.  Look at the 2018 drawing, imagine some heel, and judge for yourself.

More depth to the keel might help, but it is not essential.  That is the point that Edwin Gifford wanted to make with his half-length replica, Sae Wylfing – the photo at the top of the post shows her profile.

To be continued………..