Charting error led to the striking of an offshore oil platform, NTSB report says

Ocean Princess under way before the casualty (left); SP-83A before the casualty (right).
(Sources: ©Malcom Cotte MarineTraffic.com; Arena Offshore) 

 

From NTSB

On January 7, 2021, at 0122 local time, the bulk carrier Ocean Princess, with a crew of 24, struck the uncrewed/out-of-service oil and gas production platform SP-83A while operating in the Gulf of Mexico, 24 miles south of Pilottown, Louisiana.

No pollution or injuries were reported.

Damage to the vessel and platform was estimated at $1.5 million. 

 

 Area where the Ocean Princess contacted platform SP-83A, as indicated by a red X

 

source : U.S. Bureau of Ocean Energy Management BOEM

Background

The Ocean Princess was a dry bulk carrier built by Tsuneishi Shipbuilding of Fukuyama, Japan, in 2002 for Ocean Line Holdings of Qingdao, China, the beneficial owner of 32 vessels.
The vessel was one of 32 managed by Ocean Longevity Shipping & Management Co. in Hong Kong, China.

Built in 1990, SP-83A was a US fixed oil and gas production platform located 11 miles offshore of Southwest Pass, Louisiana and 24 miles south of Pilottown, Louisiana, in the Gulf of Mexico, on the southern edge of the safety fairway that connected the approaches to Southwest Pass and South Pass to the Mississippi River.
A four-pile steel structure in 467 feet of water that rose 73 feet above the water, the platform was 162 feet long and 81 feet wide and had three decks and a heliport.
SP-83A was painted orange and equipped with eight flashing white lights with 2-mile visibility 53 feet above the water, and a fog signal with a 2-mile range.
It had been uncrewed since 2020, when it was taken out of service. SP-83A was owned by Arena Energy and managed by Arena Offshore of The Woodlands, Texas.

 

Plot of the Ocean Princess automatic identification system history

shows the vessel’s path  until the time of the casualty.

Navigation Charts 

After the casualty, the master and the second officer noted that platform SP-83A was on the paper chart used on the bridge by the mate on watch, but SP-83A did not appear on the ECDIS.
The second officer stated that during the time leading up to the casualty he did not notice SP-83A was missing on the ECDIS.
The paper chart used on the bridge was British Admiralty chart 3857, Southern Approaches to the Mississippi River, 5th edition, December 20, 2012.
The chart was up to date and corrected with the most recent British Admiralty weekly notice to mariners.

 

BA3857 Admiralty (scale 1:150 000)

 

In the casualty location, the ECDIS drew its electronic navigation chart (ENC) information from the National Oceanic and Atmospheric Administration (NOAA) Nautical Information System (NIS) database.
When reviewing the vessel’s ECDIS correction record for the previous year, investigators found that the automatic updates to the electronic navigation charts were received and loaded weekly to both ECDIS units aboard the Ocean Princess.
The last update before the casualty was 53/21

(January 1, 2021). Neither of the two applicable NOAA ENC vector charts covering the area where the casualty occurred contained platform SP-83A.
Although the Ocean Princess ECDIS unit was up to date with chart corrections, the two ENC vector chart updates did not contain platform SP-83A, and therefore SP-83A was not shown on the Ocean Princess ECDIS unit. 

However old version of US4LA30M ENC (from 2012 GeoGarage archives)

seems to provide position info for SP-83A

Investigators also reviewed the three applicable NOAA paper navigation charts (11360, 11361, and 11366), which were up to date with the most recent notice to mariners, for the area where the casualty occurred.
SP-83A was depicted on only chart 11360 but not the other two larger-scale charts.
A representative of NOAA’s Marine Chart Division stated that platform SP-83A was added via a local notice to mariners in 1990, and the platform’s most recent revision was in 1994.
For unknown reasons, SP-83A disappeared from charts 11361 and 11366 in March 2010.
According to NOAA, ENCs were created from the raster (paper) charts, so the unexplained removal of platform SP-83A from the raster charts was critical to it also not appearing on the ENCs.

Since 2017, all NOAA ENCs have been stored in the NIS chart database and are no longer created from raster charts.
Changes to an ENC must be made through the NIS database, and critical chart corrections are issued via the Coast Guard’s local notices to mariners.
NOAA believes that, with NIS and its existing review procedure for ENC corrections and updates before public release, the error of SP-83A being omitted from ENC charts could not happen today.

The British Admiralty chart shows SP-83A while the ECDIS image does not. 

 

Navigation aids used by the Ocean Princess bridge team, with the location of platform SP-83A shown annotated by NTSB with a yellow circle (images are at different scales).
A photo of the British Admiralty chart 3857 (left) and ECDIS screenshot from the Ocean Princess fed by NOAA ENCs (right), which were up to date at the time of the casualty.
There were three platforms in the general area where the vessel was drifting.
Although platform SP-83A was depicted on the British Admiralty paper chart on the bridge, it was not marked as an obstacle with red pencil as required by the company’s SMS, nor were the other two platforms nearby.
The second officer said he was aware of the platform when he plotted fixes on the paper chart nearly an hour before the casualty but did not think it was of concern.
He also stated that he did not tell the master about the platform on the chart and assumed the master was aware of it.

Postcasualty Actions

After the casualty, Coast Guard District 8 (CGD08) issued a Broadcast Notice to Mariners via VHF radio from January 26 to February 9, which provided platform SP-83A’s position and notified mariners that the platform was not displayed on electronic charts.
On February 3, CGD08 issued weekly Local Notice to Mariners 05/21 with the chart correction to add “Platform (Arena Offshore-107-1)” to the two large-scale paper NOAA charts covering the area where the casualty occurred.
On February 11, NOAA released the automatic corrections that added platform SP-83A to the two ENC vector charts covering the casualty area.

 

 

Localization of SP-83A on current version of ENC charts (NOAA US4LA30M)

ChartError

Platform SP-83A was not charted on the official US electronic or paper navigation charts that provided the chart data to the ECDIS aboard the Ocean Princess, but the platform did appear on the British Admiralty paper chart that the mate on watch was using at the time of the casualty.
The platform had been added to the US paper charts when installed in 1990, but for an unknown reason was omitted 20 years later in 2010 and remained off the two larger-scale US paper charts (charts 11361 and 11366) and ENCs for over 11 years—until after the casualty.

 

US4LA30M ENC

Following the casualty, NOAA updated and corrected electronic and paper charts that had been erroneously missing platform SP-83A.
Because ENCs have been stored in the NIS chart database since 2017 and the normal procedure for updating ENCs changed, NOAA believes the type of error that omitted SP-83A from the charts could not happen today.

 

NOAA RNC in the GeoGarage platform

Conclusions

The National Transportation Safety Board determines that the probable cause of the contact of the dry bulk carrier Ocean Princess with the oil and gas production platform SP-83A was poor bridge resource management, which resulted in the bridge team not identifying the platform and recognizing the risk it posed to their safe navigation even though they saw its lights about 10 minutes before the casualty.

Contributing was platform SP-83A not being shown on the vessel’s electronic chart display and information system due to a charting error. 

 

Lessons Learned

Overreliance on the Electronic Chart Display and Information System 

The effective use of all available resources by a bridge team, including paper charts, electronic charts, and radars, increases collective situational awareness and contributes to a safe navigation watch.
When identifying hazards, bridge teams should avoid overreliance on a single data source by cross-checking information with available bridge resources and communicating identified risks with fellow watchstanders to ensure a shared mental model.

Increasing operator vigilance and combatting overreliance requires healthy skepticism about situations and information sources regardless of how accurate they could be, or how confident one is in their own assessment.
In this casualty, the electronic chart display and information system (ECDIS) was missing the oil platform struck by the vessel due to a charting error.
The vessel’s safety management system noted, “ECDIS is a valuable asset in assisting navigators and allowing them more time to maintain a proper lookout by providing them with more detailed situational awareness.”
However, it also warned, “navigators should always cross check ECDIS information with the other sources," and, if not used properly, “ECDIS may contribute to accidents rather than preventing them.”
The inability to recognize the fallibility of technology, such as an ECDIS, can result in operator overreliance and overconfidence that degrades sound navigation practices and negatively affects situational awareness.

 

Links : 

• Workboat : Charting error led to the striking of an offshore oil platform, NTSB report says
• NTSB : Poor Bridge Resource Management and Charting Error Led to the Striking of an Oil and Gas Production Platform
• BSEE : Accident investigation report
  

Where it all began – A race around the Isle of Wight

From America's Cup by Magnus Wheatley

The Victorian yachting scene of the early 19th Century was a very different place.
It was a time of gentleman’s wagers as the transition from the old world to the new created opportunity for the wealthy to prove their yacht’s capabilities.
The Royal Yacht Squadron was founded on 1st June 1815 at the Thatched House in London with a principal objective far removed from what we know today.
Back then, club members merely gathered primarily to execute boat-handling skills and manoeuvres to signals unique to the Squadron and it wasn’t until 1818 when the first recorded monies were initiated for races between local Cowes boatmen at the annual regatta.

Up to that point, wagers were an in-house affair between members, with the first recorded in 1815 between two cutters weighing in at 60 and 65 tons respectively (The Charlotte and The Elizabeth) and it was a period of increasingly larger sums being placed and intense competition between members.
Indeed, wealthy Victorians in the first half of the 19th Century in England found great pleasure in wagers – it was almost the light entertainment of the day.

As racing became a thing, some six trophies were crafted at the finest silversmiths and even the King donated a beautiful tankard but as the middle of the century fast approached, yacht racing at the Royal Yacht Squadron, who didn’t move into their impressive Castle at the entrance to Cowes harbour until much later in 1857, was waning.
A new Commodore, the Earl of Wilton, was appointed in 1849 and quickly took on a remit to broaden the Club’s appeal.
At the May meeting in 1851, a £100 Cup was waged for a race around the Isle of Wight with one eye on attracting international participation, in particular from the United States.

But skip back to the year 1844 and the real genesis of today’s America’s Cup can be found with the formation of the New York Yacht Club aboard John Cox Stevens’ schooner Gimcrack.
With Prince Albert’s Great Exhibition set to be held at the Crystal Palace in London in 1851, Stevens and five other founding members of the NYYC took it upon themselves to create a vessel capable of showcasing the great skills and innovations of US shipbuilding.

As was the time, a wager was offered to George Shuyler (one of the six original founders of the NYYC) by East Coast boatbuilder William Brown in a letter that set out to create a craft “faster than any vessel in the United States brought to compete with her” for the not inconsiderate sum of $30,000.
It was a no-lose bet for the founders, as they deemed that if Brown was correct, they could win considerable prize sums once the yacht had crossed the Atlantic, and the yacht ‘America’ was duly commissioned.

In customary America’s Cup style, repeated down the ages through to this very day, the yacht America was somewhat radical from the outset.
She was built to withstand an Atlantic crossing planked with beautiful three-inch thick white oak set on five different varieties of hardwood framing and diagonal iron bracing.
The deck was a yellow pine of some two and a half inches whilst the hull was copper sheathed to just above the waterline.
The Certificate of Registry, issued on the 17th June 1851 by the New York Customs House, states that America was 93ft 6inches long with a beam of 22ft 6inches and a draft of 9ft.
She weighed in with a tonnage just over 170.

 

A few days after registry, on the 21st June 1851, America set sail for Le Havre in France, replete with grey primed topsides for finishing off ahead of race preparation across the English Channel away from prying British eyes.
She arrived on July 9th, 1851, and entered an intense period of refit.
The topsides were enamelled in black and racing sails, made of cotton (the British boats used heavy flax) were laced to the spars – unconventional at the time.

John Cox Stevens and his brother Edwin A.
Stevens took charge of the vessel from here on and on 31st July 1851 they left Le Havre to travel to the Isle of Wight and challenge the very best that the assorted yacht clubs in England could muster.

Arriving off the north side of the Island that night in thick fog they anchored off the sands of Ryde Town and waited for the arrival the following morning of the cutter Lavrock to guide them up to Cowes.
Lavrock was known as one of the fastest of the English fleet and America was hesitant to sail against them, laden down as they were still with stores for the trip across the Atlantic.
But after starting considerably astern, quickly the crew of America found they could sail higher to the wind at a consistently faster speed and overtook Lavrock, resting just off Cowes at anchor a third of a mile ahead in short order.

The Earl of Wilton came aboard and welcomed the New York Yacht Club’s rapid vessel and its crew to Britain.
The London newspaper, The Times, reported that the vessel had arrived and alluded to its speed saying that it had the effect which “the appearance of a sparrow hawk on the horizon creates among a flock of wood pigeons or skylarks,” and in an instant the wagers and bets that had been mooted by owners of commensurate old-world yachts or on behalf of various royal clubs quickly dried up.

However, this was a time when yacht design was of fascination.
The old and the new world vessels wanted to pitch against each other to see and assess relative speeds and characteristics.
America was seen as ‘radical’ with a refined rigging arrangement, smaller sail area and sleeker form.
She quickly became a vessel to watch as she lined up alongside or astern of others of the English fleet in races from both the Royal Victoria Yacht Club and the Royal Yacht Squadron that she was ineligible to compete in that summer, owing to the ownership structure or membership status of the crew.
That she was fast, was never in doubt.

 

The first, and perhaps only, real test for America was the Royal Yacht Squadron’s £100 Cup initiated by the Earl of Wilton to be sailed on a clockwise course around the Isle of Wight on August 22nd, 1851.
A total of 18 yachts entered but only 15 made it to the starting line varying from the 392-ton, three-masted schooner ‘Brilliant’ to the 48-ton cutter Volante.

As was tradition (and a tradition that lasts to today), cannon fire was issued by the Royal Yacht Squadron at 10am to signal the start of the race with all the vessels sat at anchor on their stations to follow the easterly flowing tide down the Solent.
As the fleet took off in moderate to light winds, America overran her anchor and was quickly spun round in the breeze to face the west and for the first few hours of the most famous race in yachting’s history, it was a game of catch-up.
Setting a different sail-plan, much smaller than the rest of the fleet - the Lawsons History of the America’s Cup documents that: “The America went easily for some time under mainsail (with a small gaff-top-sail of a triangular shape braced up to the truck of the short and slender stick which serves as her main-top-mast), foresail, fore-stay-sail, (jib) and jib (flying-jib) while her opponents had every cloth set that the Club regulations allow.” Indeed, the British yachts had hoisted vast acres of flax sailcloth, but with cotton flat-cut sails laced to the spars and a better hull-form, America quickly started to pull through the fleet.

By the No Mans Land buoy off Seaview, it was a race amongst the smaller cutters who could ply their way through the water and maintain their speed in the moderate airs ahead of the heavier schooners.
An hour and a half after the starting signal, America seized the lead from the 48ft Volante having jockeyed and swapped positions down the waterway just before the Nab Light that marked the eastern approaches to the Solent.
And it was here where the first, and possibly longest lasting, controversies of what became the America’s Cup, occurred.

An unwritten rule, perhaps a memorandum of understanding between gentlemen members of the Royal Yacht Squadron and accepted by the other notable royal clubs, dictated that yachts would pass to the east of the Nab Tower light buoy, leaving the navigation mark to starboard as they filed along on their way to the southern-most tip of the Island.

However, Robert Underwood, the British pilot who was aboard the America having been recruited by the US Consul in Southampton to guide the vessel in these trickiest of coastal waters, stuck by the letter of the instructions for the race that he had received.

America tacked inshore and passed to port inside the buoy before the Yaverland foreshore and on to Sandown and Shanklin.

 

Although America was clearly faster, it was anything but plain sailing on the windward leg up against the tide to St Catherine’s Point as she held a one-mile lead over the Aurora, with the Volante having sprung her bowsprit, the Arrow going aground and the Alarm standing by to assist.
The fleet was dwindling.
America’s innovative jib boom snapped just off Dunnose Head although for the Sailing Master, Dick Brown, it was somewhat of a relief as he didn’t feel jib booms should be carried to windward.
Once the crew had cleared the debris with minimal loss in position, America increased her pace thus confirming Brown’s hunch.

However, it was a long haul around the tricky coastal waters of the back of England’s famous Isle as the Lawsons History of the America’s Cup chronicles: “notoriously one of the most unfair to strangers that can be selected, and indeed it does not appear a good race ground for anyone, inasmuch as the currents and tides render local knowledge of more value than swift sailing and nautical skill.” America finally rounded the Needles, an outcrop of rocks that mark the western end of the Solent at 5.40pm some seven and a half miles ahead of the 84ft cutter Aurora with just the nine miles of the Solent down to Cowes left to run.

Almost immediately after rounding the Needles and entering the narrow, deep channel down through the approaching Hurst narrows, the America ran slowly past the Royal Yacht, sat at anchor in Alum Bay with the Queen (Victoria) and Prince Albert present on her decks.

As is customary, the ensign was lowered (quite a thing for Republicans to do) and Commodore Stevens of the NYYC doffed his cap as a mark of respect.
As the winds lightened into the evening, it was a long haul down to Cowes with the Aurora closing in on America to within just a few minutes.

According to the Lawsons History of the America’s Cup: “The evening fell darkly, heavy clouds being piled along the northern shore of the strait; and the thousands who had for hours lined the southern shore, from West Cowes long past the Castle, awaiting anxiously the appearance of the winner, and eagerly drinking in every rumour as to the progress of the match, were beginning to disperse, when the peculiar rig of the clipper was discerned through the gloom, and at 8h 34m.
o’clock (railway time 8h 37m., according to the secretary of the Royal Yacht Squadron) a gun from the flagship announced her arrival as the winner of the Cup.
The Aurora was announced at 8h.
58m.; the Bacchante at 9h.
30m.; the Eclipse at 9h.
45m.; the Brilliant at 1h.
20m.
(Saturday morning).
No account of the rest.”

As the America, with her crew of 13 onboard passed the flagship, she was, according to Lawsons: “received with the most gratifying cheers.
Yankee Doodle was played by the band.”

But it was back up at the Needles at the western end of the Solent where possibly the most famous phrase of the America’s Cup, a phrase that many of today’s sailors use and live by, was supposedly uttered to Queen Victoria by a signalman onboard the Victoria & Albert Royal Yacht as he peered from the deck down the Solent:

 

“Say signal-master, are the yachts in sight?”
“Yes, may it please Your Majesty.”
“Which is first?”
“The America.”
“Which is second?”
“Ah, Your Majesty, there is no second.”

Perhaps an embellishment of the truth, the name of the “perspicacious” signal-master was never recorded but the tale and its succinct line has stuck with the America’s Cup since and beautifully encapsulates the competition.

When the news finally reached the United States some two weeks after the race, it was received with “general satisfaction, quietly expressed” according to Lawsons.
“In Boston the news was received during a celebration at the State House, of the opening of railway communication between the United States and the Canadian provinces.
Daniel Webster (Congressman and US Secretary of State) was addressing a large audience in the hall of the House of Representatives.
He broke off in his speech to announce the victory: “Like Jupiter among the Gods, America is first, and there is no second.”

There really is no second in the America’s Cup.

 

New Zealand (Linz) layer update in the GeoGarage platform

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Theories of giant waves that suddenly appear and vanish

Huge wave hits Dunbar oil rig North Sea

 

From Maritime Executive by Harry Valentine

Maritime folklore tells stories of giant waves that suddenly appear on the ocean and disappear just as quickly.
While many people dismiss the existence of such waves as mythology, there are accounts of oil rigs and ships having encountered giant waves and giant troughs that suddenly appear and disappear.
There are theories that seek to explain such occurrences that could occur more frequently as a result of climate change.

Introduction:

During December 1942, the Queen Mary sailed westbound into a storm on the North Atlantic carrying almost 11,400 American soldiers and pushing through swells of 50 to 60-feet in height.
It suddenly encountered a super trough and hit broadside by a giant wave estimated at 90-feet height.
The ship heeled over to 52-degrees and within 3-degrees of its limit before slowly righting itself.
During early 1960’s, the Union-Castle Line’s Pendennis Castle sailed from Durban to Cape Town when it fell into “a hole in the ocean,” causing the ship to heel over to 45-degrees, its limit.

Fortunately, the Pendennis Castle was able to right itself.
During July 1909, the 10,000-ton SS Waratah carrying 211-people suddenly disappeared without trace while sailing from Durban to Cape Town.
It was discovery during 1999 resting upright on the seafloor, indicating that it had sunk very rapidly and possibly the result of having encountered a giant wave.
During February 1982, huge waves estimated to exceed 65-feet pounded the semi-submersible oil rig named Ocean Ranger and caused it to sink offshore from Newfoundland, Canada.
During December 2008, a giant wave hit the Dunbar oil rig in the North Sea. 

 

Theory of Sea Waves:

There is general agreement that wind blowing over large expanses of ocean produces waves on the ocean surface.
When waves approach a coastline with decreasing water depth, the leading edge of each wave slows as the trailing edge catches up to increase wave height.
As wind speed increases, wave height and wave speed both increase.
While tiny waves break very close to shoreline, larger waves break further away from the shoreline indicating a relationship between water depth and the combination of wave height and wave speed.
Seafloor topography has potential to affect wave height and where waves break.

Shallow bodies of water such as Lake Erie, North Sea and Bay of Biscay are notorious for storm driven wave conditions.
The Mid-Atlantic Ridge provides a shallow zone along the shipping route between North America and Europe with potential to cause large waves as winter approaches each year.
At such time and as a result of a combination of rarely occurring factors, steadily increasing wind speed along the American east coast has potential to produce waves that could coalesce and break at mid-ocean above the Mid-Atlantic Ridge, such as the wave that Queen Mary encountered.

Seafloor Topography:

The seafloor topography under several bodies of ocean provides locations where large offshore waves are likely to occur.
While the southern region of the Bay of Biscay reaches depths in excess of 9,000-feet, depths in the northern region are less than 300-feet providing a 30-to-1 ratio.
That seafloor profile extends westward into the Atlantic Ocean and across the international shipping channel located west of Portugal and Spain where over the distance of a few miles, water depth changes from more than 9,000-feet to less than 600-feet.
The international shipping lanes that connect to Western Europe pass through this region.

Winds blow across vast expanses of the North Atlantic producing waves that enter this region where wave height increases.
Waves moving south from the Norwegian Sea into the North Sea also encounter a sudden change in water depth between Scotland and southern Norway, where large waves have a propensity to occur.
Water depth off the South African coast between Durban Port Elizabeth rapidly decreases toward shore over a comparatively short distance and especially offshore from East London where a shallow zone extends further into the Indian Ocean and where large waves frequently occur.

Changing Climate:

Climate change has the propensity to increase storm severity in many coastal regions internationally.
More powerful winds blowing at steadily increasing speed over large expanses of ocean would produce larger and faster moving waves that are more likely to be affected by deeper level seafloor topography.
The result would be an increased likelihood of successive waves coalescing into the occasional supersize wave that would break far offshore in regions where sea depth rapidly decreases.
There are several locations in the world’s ocean where water depth decreases offshore from over 10,000-feet to under 600-feet, where super waves are likely to occur.

Conclusions:

It is perhaps a forgone conclusion that ships will encounter storms at sea and on rare occasions during such storms, a wave of extreme height.
In the history of shipping, ships have encountered rogue waves and survived as was the case for the Queen Mary and the Pendennis Castle that were both larger than the ill-fated Waratah.
As future international trade increases, greater numbers of large ships will sail across the ocean and through regions where the seafloor rapidly changes height in mid-ocean.
There will likely be increased future reports of ships having encountered sudden large waves at mid-ocean.

Links :

• GeoGarage blog : Enormous 'rogue waves' can appear out of nowhere. Math is revealing their secrets. / Four-story high rogue wave breaks records off the coast of Vancouver Island / Terrifying 20m-tall 'rogue waves' are actually real / Oxford scientists successfully recreated a famous rogue wave ... / How dangerous can ocean waves get? Wave comparison / Study finds massive rogue waves aren't as rare as previously ... / Rogue wave theory to save ships / How rogue waves are created in the ocean / Rogue waves captured / 19-meter wave sets new record - highest significant wave ... / Science investigates freak waves

Map may show evidence of Wales' Atlantis off Ceredigion

The legend states the lost kingdom of Cantre'r Gwaelod sunk into the sea off the Welsh coast

image : Getty Images

From BBC by Neil Prior

The Welsh legend of Cantre'r Gwaelod, a lost land sunken below Cardigan Bay, has persisted for almost a millennium.

First written about in the mid-13th Century, it is likely the myths and legends surrounding the Welsh Atlantis date from long before that.

Yet there has never been any definitive geographical evidence for the mythical land… until now, perhaps.
A medieval map has been uncovered which depicts two islands off the Ceredigion coast - now lost to history.

Simon Haslett, honorary professor of physical geography at Swansea University, went in search of lost islands in Cardigan Bay while he was a visiting fellow at Jesus College, Oxford.
Along with David Willis, Jesus Professor of Celtic at the University of Oxford, they have presented evidence of two islands depicted on a medieval map, each about a quarter the size of Anglesey.

 

 The 13th Century map depicts a medieval Wales with two large islands off the west coast that do not exist today

Image : Bodleian Libraries, Univerity of Oxford

 

www.goughmap.org/map/

(North at West : rotate -90°)

 

One island is offshore between Aberystwyth and Aberdyfi and the other further north towards Barmouth, Gwynedd.

Localization with the GeroGarage platform (UKHO nautical map)

 

Prof Haslett explained that the two islands are clearly marked on the Gough Map, the earliest surviving complete map of the British Isles, dating from as early as the mid-13th Century.
"The Gough Map is extraordinarily accurate considering the surveying tools they would have had at their disposal at that time," he said.
"The two islands are clearly marked and may corroborate contemporary accounts of a lost land mentioned in the Black Book of Carmarthen."

Professors David Willis (left) and Simon Haslett (right) researched the lost islands of Cardigan Bay

image : Jesus College Oxford 

 

The map is held in the collections of the Bodleian Library at Oxford University.

Cardiff University's Welsh folklore expert Dr Juliette Wood - who was not involved in this research - said the Black Book's account was key to anchoring the story in Welsh myth.
"The Gough Map may have its origins around 1280, shortly before that, around 1250, you have the Black Book of Carmarthen.
"It describes Gwyddno Garanhir's country called Maes Gwyddno (Gwyddno's Field). It was flooded because the well-keeper (Mererid) left the cover off the well."

Fact within folklore?

Drawing upon previous surveys of the bay and understanding of the advance and retreat of glaciers and silt since the last ice age about 10,000 years ago, Profs Haslett and Willis were able to suggest how the islands may have come into existence and then disappeared again.

Prof Haslett also suggested it may explain some of the local folklore.
He said: "I think the evidence for the islands, and possibly therefore the legends connected with them, is in two strands.
"Firstly, coordinates recorded by the Roman cartographer Ptolemy suggest that the coastline at the time may have been some 13km (8 miles) further west than it is today.
"And, secondly, the evidence presented by the Gough Map for the existence of two islands in Cardigan Bay."

The Gough Map depicts two islands in Cardigan Bay - both about a quarter of the size of Anglesey

source : Getty Images

He added folk legends of being able to walk between lands now separated by sea could be a folk memory stemming from rising sea levels after the last ice age.
"However, legends of sudden inundation, such as in the case Cantre'r Gwaelod, might be more likely to be recalling sea floods and erosion, either by storms or tsunami, that may have forced the population to abandon living along such vulnerable coasts," he added.
"In roughly a millennium, from Ptolemy's time to the building of Harlech Castle during the Norman period, the seascape had completely altered."

Roman cartographer Ptolemy mapped much of Europe in precise detail

Ptolemy's map of Great Britain and Ireland (1467 copy)

source : wikipedia

"Later maps show the islands had disappeared, yet further up the coast at Harlech, the castle which was built to have a strategic advantage on the coastline now found itself more or less land

slocked," he added.
"The erosion of any islands here would have released boulders that are likely to have contributed to the accumulation of the distinctive stone structures known locally as sarns."

Dr Wood believes these sarns have played a vital part in perpetuating the story.

'Re-enchanting the land'

"People now as much as then want to find a way of explaining things which seem simply unexplainable; especially during tough times," she said.
"I've seen the sarns myself, and they are incredibly convincing. You could easily believe that their uniform structure was once part of a lost civilisation, however the catch is that most of these stories don't come back into fashion until the 18th Century
"I call it re-enchanting the land, the romanticists amongst the Celtic population want to find meaning and a belief system to make sense of the current hardships."

Dr Wood added that similar "Atlantis" legends can be found around most of the world, particularly in Europe.
"These migratory stories emerge when the facts fit the myth. They come and go all over the place, but especially when phenomena like the sarns appear.
"Rather than saying that the discovery of the island proves the folklore, I'd say that the proof is coincidental, and that the two truths can exist independently of each other."

However, Prof Haslett warned his findings could have more bearing on the future than the past.
"These processes didn't happen just once, they're still on-going."

"With rising sea levels and more intense storms it's been suggested that people living around Cardigan Bay could become some of Britain's first climate change refugees, within our lifetimes."
Profs Haslett and Willis have published their findings in the journal Atlantic Geoscience

Links :

• Cantre’r Gwaelod: The Mysterious Legend of the Ancient Sunken Kingdom Known as the Welsh Atlantis
• BBC: Cantre’r Gwaelod – The Lost Land of Wales
• NYTimes : A Sunken Kingdom Re-emerges
• DailyMail : Storm Francis uncovers part of a petrified Welsh woodland that has been submerged for 4,500 years and inspired the legend of the 'Lost Hundred'
• The Guardian : Prehistoric forest uncovered by storms in Cardigan Bay