FEATURES

DEEPWATER HORIZON

Deepwater Horizon - What Have we Done to Deserve This
Deepwater Horizon - After the BP Report
Deepwater Horizon - The Investigation
The Deepwater Horizon and the Late MMS.
The Deepwater Horizon - PR and Politics
The Deepwater Horizon - Forces at Work
The Deepwater Horizon - Where Are We Now?
ROVs, Risers and Mud
The Deepwater Horizon - Later
Something about the Deepwater Horizon Accident
Channelling the Oil Leak
Preventing Fires and Explosions on Offshore Installations

OTHER ACCIDENTS
The Loss of the Normand Rough
The Bourbon Dolphin Accident
The Loss of the Stevns Power
Another Marine Disaster
Something About the P36
The Cormorant Alpha Accident
The Loss of the Ocean Express

OPERATIONS
The Life of the Oil Mariner
Offshore Technology and the Kursk
The Sovereign Explorer and the Black Marlin

SAFETY
The ALARP Demonstration
PFEER and the Dacon Scoop
Human Error and Heavy Weather Damage
Lifeboats & Offshore Installations
More about PFEER
The Offshore Safety Regime - Fit for the Next Decade
The Safety Case and its Future
Jigsaw
Collision Risk Management
Shuttle Tanker Collisions
A Good Prospect of Recovery

TECHNICAL
The History of the UT 704
The Peterhead Connection
Goodbye Kiss
Uses for New Ships
Supporting Deepwater Drilling
Jack-up Moving - An Overview
Seismic Surveying
Breaking the Ice
Tank Cleaning and the Environment
More about Mud Tank Cleaning
Datatrac
Tank Cleaning in 2004
Glossary of Terms

CREATIVE WRITING
An Unusual Investigation
Gaia and Oil Pollution
The True Price of Oil
Icebergs and Anchor-Handlers
Atlantic SOS
The Greatest Influence
How It Used to Be
Homemade Pizza
Goodbye Far Turbot
The Ship Manager
Running Aground
A Cook's Tale
Navigating the Channel
The Captain's Letter

GENERAL INTEREST
The Sealaunch Project
Ghost Ships of Hartlepool
Beam Him Up Scotty
Q790
The Bilbao OSV Conference

ICEBERGS AND ANCHOR-HANDLERS

Every year in the calving grounds of Greenland’s glaciers, 20,000 to 40,000 icebergs are born.  Carried north on the currents, they circle Baffin Bay before appearing in the North Atlantic the following season.  Fewer than 500 drift south to menace shipping and oil installations off the coast of Newfoundland, splintering and fracturing, breeding smaller pieces known as growlers and bergy-bits.  Everyone knows the Titanic’s story.  Let it not be lost on us that the medium sized iceberg she struck was south of Boston.  As recently as 2002 the shrimp trawler BCM Atlantic struck an iceberg, sinking in five minutes.  Ship’s captains can alter course, an option not available to the Hibernia Platform that can only remain stationary as danger approaches.

Designed against the impact of sea ice and icebergs up to one million tonnes with no damage, the platform would suffer repairable damage from a six million tonne iceberg, the largest estimated berg capable of entering the 80 metre waters surrounding Hibernia.

Research carried on by the Centre for Cold Ocean Research Engineering (C-CORE) has shown that serious damage can be caused by growlers and bergy-bits weighing as little as 500 to 1000 tonnes.   Having installed what amounts to a giant weigh scale hung on a cliff in Newfoundland, they smash small icebergs against the platform.  Information from these tests has not only given us an idea of how hard ice is, like crushed asphalt, but will aid the builders in the design and selection of materials for  tomorrow’s ships.

Support vessels servicing the rigs are also in danger, not from the big bergs, readily visible as they tower from the ocean, but from the small growlers and round-tops, often undetectable on radar and virtually impossible to see in the North Atlantic waves.  In some areas, sheer numbers aggravate the problem.  The drill ship West Navion had to deal with over 200 bergs and deflect more than seventy while drilling in the Davis Straight.  Further south the Henry Goodrich and the Terra Nova FPSO, capable of handling 150,000 b/d, don’t want them around.  Although capable of moving to avoid contact with an iceberg, downtime and loss of production time makes this unacceptable.  For the Terra Nova FPSO just multiply its daily production by the current price of oil.  Hiring a tug to move the ice is cheap by comparison.

Icebergs don’t just bump into things, if deep enough, they gouge out troughs in the seabed of the Grand Banks varying from 10 to 150 metres wide.  Any pipelines or fibre optic cables in their path would be gathered up like so much spaghetti.

Ships and icebergs share one thing in common; both only need a small deviation to avoid a collision and oil exploration off Canada’s east coast has spawned a whole new line of work for the AHTSV - iceberg towing.  In its simplest form this involves circling the iceberg with a floating line, often eight-inch polypropylene, sending enough steel cable over the stern to take up the slack and set the rope, then tow the berg a sufficient distance so the current will carry it safely past the rig.  For Jeff Murrin, captain of the Atlantic Eagle, the challenge is met with 1200 metres of rope, 14,400 horsepower and 150 tonnes of bollard pull.  Even so, the pace is slow.  An iceberg 307 metres long by 235 metres wide with 10 metres above the water required his services.  Using side scan radar, it draught was established at 95 metres, and when the Atlantic Eagle hooked on to it, they had 7 ½ million tons on the wire.  Towing bergs that size often takes half a day to reach one knot.  Occasionally the rope will tear loose from rotten ice and ride over top of the berg, or the iceberg may roll over.  Small chunks of ice are moved by prop washing, repeatedly backing close, then using the ships propeller wash to create a man-made wave and thrust the berg away, often for a distance of half a mile or more.

When practical, the ship’s water canon are be used to move or break down the ice.  Atlantic Eagle has two of them capable of delivering 3800 tons of water an hour.

A more novel approach taken by enterprising Newfoundlanders is to haul the ice ashore, melt it to pristine water and make ICEBERG Vodka out of it.

All these measures are but temporary, for Mother Nature will take over the task as summer wears into July.   We wrest riches from the seabed at our peril and have learned to use technology to make it safe.  Towing icebergs may not be high tech but every rig worker off the east coast of Canada sleeps easier because Maersk and Atlantic Towing ships are on the job.

For a good picture of this activity taking place go to the 2003 photo contest section and scroll down to Hugh Dunlop picture of the Maersk Gabarus towing a 5 million ton iceberg.

Ted Caucutt.

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