Advances in Deepwater Cable
Maintenance Through New Grapnel
Technology
Jeremy Featherstone & Andrew Thomas
Blue Ocean Projects Ltd & Ocean Cable Technologies Ltd
Presenters Profile - 1
Jeremy Featherstone is a Chartered Engineer,
previously at SMD and then C&W/Global
Marine and is now Director of Blue Ocean
Projects Ltd. Cable protection & subsea
equipment background.
Blue Ocean Projects Ltd provides consultancy,
project management and technology
development to subsea power cable, offshore
umbilicals and submarine telecommunication
cable sectors
www.blueoceanprojects.com
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picture
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Jeremy
Featherstone
Director
[email protected]
+44 7887 824 186
Presenters Profile - 2
Andrew Thomas prior to founding Ocean Cable
Technologies Ltd in March 2002 was Product
Manager for the Universal Jointing division of
Global Marine Systems Ltd. Andrew has added
strength to his engineering background by
attaining both a DMS and MBA.
Ocean Cable Technologies Ltd develops and
manufactures technology and services to the
submarine cable, offshore oil, gas and power
cable industries.
www.octl.org.uk
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Andrew Thomas
Managing Director
[email protected]
+44 2392 864 888
Contents
Deepwater Cable
Recovery
1850 - 2006
• Fault Rates & repairs
• Conventional methodology
• Early grapnels
• Introduction of lightweight
cables
• Recent R&D by authors
2007 onwards • The next steps
Deepwater Fault Rates
Kordahi & Shapiro (SubOptic 2004): typical
fault rate for deepwater (1000m plus) is less
than 0.1 faults per year per 1000km
 Implies less than 50 such deepwater repairs
per year globally
 But deepwater faults can be more significant
than shallow ones…
Deepwater Repairs
Compared to shallower water:
 longer transit to repair site
 longer to deploy grapnels and recover cable
 Weather more challenging
 More stock repair cable used
 Taiwan earthquake of December 2006 –
short term crippling of networks, multiple
deepwater repairs required
Conventional grapnel recovery
 Grapnel drive 1 - cut
 Grapnel drive 2 – hook first end
 Grapnel drive 3 – hook second end
 Each time the cable must be located anew
Cut & Hold Grapnels
Cut & Hold grapnel will reduce drives from 3
to 2, saving typically 18-24hrs
Less stock (repair) cable required
Repair can be closer to crossing point,
branching unit or repeater
Industry has successfully reduced jointing
times – next goal: reduce cable recovery times
1850-2006
Not a new problem!
First designs of cut and hold grapnels in 1874
Lucas grapnel patented 1888
First used in 1891 - successfully cut and
brought up cable from 3000m water depth
Scotia
Lucas grapnel
The Lucas Cut & Hold Grapnel
Lucas design with detail improvements
operational over some 70 years
A patent application of 1956 shows detail
improvements only to Lucas’ ‘well known
design’
1891 wasn’t only a big year for grapnels….
Advances in Automobiles
1891
First car manufacturer:
Panhard - Levassor
Did 140miles at 6mph
2007
Successor:
Citreon C6
Top speed 143mph
Advances in Aeroplanes
1891
First glider flight:
Otto Lilienthal, Germany
Flew up to 1000ft
2007
Successor:
Boeing 787 Dreamliner
Cruises at Mach 0.85
Advances in Deepwater Grapnels
1891
2007
Successful timesaving
technology for cable
recovery introduced
No time saving
technology for cable
recovery
in widespread use
?
The Future
Our Feasibility Study Concluded:
Main technical limitations of previous
designs
Main technical barriers to be overcome
Design principles for future technology
Impact of Lightweight Cables
Advent of lightweight cables in 1960s –
strength member now on inside of cable not
external
External grip much harder– low friction
polyethylene not steel wires
In response more complex grapnels were
developed but not in widespread use today
A cut and hold solution for LW
cable
Limitations?
Irregular use - confidence and expertise
difficult to establish?
Hydraulics too complex? too large?
The more complexity, the bigger the barrier
to adoption
Conclusion – simple compact solution, like
Lucas grapnel is required, but suited to LW
cables
Ongoing R&D by the authors
Capability exists to locate cable and cut cable
Principal focus on gripping cable to
accommodate recovery loads
Technology must overcome problem of cable
filleting
Ongoing R&D by the authors
Ocean Cable Technologies Ltd and Blue
Ocean Projects Ltd built a test rig in 2005
Undertook further research and test program
Demonstrated the ‘filleting’ problem
Further demonstrated that increasing the grip
force to distort the cable did not assist
Test rig and ‘filleting’ seen in action
Ongoing R&D by the authors
Results
Developed concepts to overcome filleting
condition and grip directly onto inner strength
member
Retest and verified results
Registered international patent application
Funding sought to continue program and
implement full working deep sea grapnel ready
for sea trials
Way Forward
Good News
Further development funding secured from
UK Department for Trade & Industry
Regional Agency
Alcatel-Lucent to provide funding and sea
trails for the development of this new
technology
Conclusion
Our Aim – to introduce a simple, purely
mechanical cut and hold grapnel for
deepwater repairs back into the
submarine telecommunication industry
Thank you
www.blueoceanprojects.com
www.octl.org.uk