Subsea Operational Support

J+S provides specialist operational support services for subsea control systems, power distribution equipment, umbilicals and offshore infrastructure. Our experienced engineers support operators, contractors and OEMs with testing, fault diagnostics, commissioning, mobilisation and offshore intervention activities worldwide.

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Offshore Support When It Matters Most

Rapid response offshore support, testing, diagnostics and intervention services for critical subsea infrastructure.

When offshore equipment fails, rapid access to experienced engineering support can significantly reduce downtime, minimise operational risk and maintain project schedules.

J+S provides practical operational support solutions for subsea control systems, electrical and hydraulic infrastructure, cable systems and intervention equipment. Our team combines workshop expertise with offshore experience to deliver responsive support both onshore and offshore.

Whether supporting planned operations, commissioning activities or emergency response requirements, we help clients maintain safe and reliable offshore operations.

Our Operational Support Capabilities

Rapid Response Support

24/7 engineering support for urgent offshore and operational requirements.

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Offshore Personnel

Qualified offshore personnel experienced in subsea control systems, testing and intervention activities.

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Fault Diagnostics

Electrical, hydraulic and fibre optic fault investigation and troubleshooting services.

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Testing & Commissioning

Support for commissioning, verification and system readiness activities.

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13 J+S Case Study Subsea Equipment Design & Modifications 1

Equipment Mobilisation

Preparation, testing and deployment support for offshore equipment and infrastructure.

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Strategic Spares Support

Management of critical spares and replacement equipment to reduce downtime.

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Hydraulic Testing & Flushing Services

J+S operates dedicated hydraulic flushing, testing and cleanliness verification facilities supporting subsea equipment and offshore infrastructure.
Capabilities include:

  • Hydraulic flushing
  • Pressure testing
  • Cleanliness monitoring
  • Control fluid management
  • Hyperbaric testing support
  • System verification

Our facilities enable rapid turnaround for both planned and time-critical work scopes.

Offshore Equipment Management

We provide complete management and preparation of offshore equipment including:

  • Umbilicals
  • Jumpers
  • Reelers
  • Downlines
  • Test equipment
  • Deployment hardware

Equipment can be prepared, tested and delivered quayside ready for mobilisation, reducing offshore preparation time and project risk.

Testing & Diagnostic Services

Our engineers provide a comprehensive range of testing and fault-finding services to support offshore operations.

Electrical Testing

  • Insulation Resistance (IR)
  • Continuity Resistance (CR)
  • Power system verification
  • Electrical fault diagnostics

Fibre Optic Testing

  • OTDR testing
  • Fibre diagnostics
  • Signal verification

Cable Diagnostics

  • Time Domain Reflectometry (TDR)
  • Cable fault location
  • System troubleshooting

Sensor Testing

  • Sensor diagnostics
  • Calibration verification
  • Repair and replacement support

Umbilical Testing

  • Electrical terminations
  • Hydraulic terminations
  • Fibre optic connections

Strategic Spares & Legacy Equipment Support

Maintaining access to critical components is essential for reliable offshore operations.
J+S supports operators through:

  • Strategic spares management
  • Connector and sensor storage
  • Obsolescence management
  • Legacy equipment support
  • Refurbishment and recertification services
  • Legacy Locker™ asset recovery solutions

This integrated approach helps reduce lead times and improve operational resilience.

Featured Operational Support Projects

Real-world examples of how J+S operational support deliver results for our clients.

10 J+S Case Study SCM Communications for Decommissioning 1

SCM Communications

Resolving communication challenges within subsea control systems during decommissioning operations.

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14 J+S Case Study Umbilical Disconnection & Wet Store 1

Umbilical Disconnection Project

Operational support and intervention services for complex subsea infrastructure activities.

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9 J+S Case Study Power and Signal Umbilical Simulators 2

Power & Signal Umbilical Simulators

Testing and verification solutions supporting offshore operations and diagnostics.

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View All Case Studies

Why Choose J+S?

he engineering partner you can rely on for practical, cost-effective subsea solutions.

Testing & Diagnostic Expertise

Comprehensive electrical, hydraulic and fibre optic testing capabilities.

Offshore Experience

Experienced personnel supporting projects worldwide.

In-House Facilities

Workshop, testing, flushing and preparation facilities supporting rapid mobilisation.

Full Lifecycle Support

From engineering design through operational support, refurbishment and decommissioning

Rapid Response Capability

Support available for urgent operational and offshore requirements.

Need Operational Support?

Whether you’re planning an offshore campaign, investigating a fault or mobilising critical equipment, our engineering team is ready to help

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Contact Our team
Mark Patterson Non-Executive Chair

Mark Patterson

Non-Executive Chair

Mark’s career spans five decades, marked by entrepreneurial success and visionary leadership across various sectors, including offshore marine technology, subsea oil and gas, green energy storage, and more.

With a track record of leading businesses through start-up, growth, acquisitions, and transformations, Mark’s expertise lies in strategic decision-making, mentoring, and brand management.

He has overseen multimillion-pound projects, pioneered new technologies, and guided companies to international recognition, such as the underwater GPS NASNet®.

His leadership style is direct, inclusive, and based on trust, empowering teams to excel.

Mark’s achievements include managing high-profile global companies, such as Balmoral group, Nautronix and Well-Safe Solutions, where he played key roles in groundbreaking projects. Global explanation and high growth.

Outside of business, Mark is deeply committed to family and charity work, with a passion for shooting, boating, and car collecting. As an experienced executive, he remains dedicated to fostering success by identifying future opportunities and mentoring the next generation of leaders.

Mark Patterson Non-Executive Chair

Mark Patterson

Non-Executive Chair

Mark’s career spans five decades, marked by entrepreneurial success and visionary leadership across various sectors, including offshore marine technology, subsea oil and gas, green energy storage, and more.

With a track record of leading businesses through start-up, growth, acquisitions, and transformations, Mark’s expertise lies in strategic decision-making, mentoring, and brand management.

He has overseen multimillion-pound projects, pioneered new technologies, and guided companies to international recognition, such as the underwater GPS NASNet®.

His leadership style is direct, inclusive, and based on trust, empowering teams to excel.

Mark’s achievements include managing high-profile global companies, such as Balmoral group, Nautronix and Well-Safe Solutions, where he played key roles in groundbreaking projects. Global explanation and high growth.

Outside of business, Mark is deeply committed to family and charity work, with a passion for shooting, boating, and car collecting. As an experienced executive, he remains dedicated to fostering success by identifying future opportunities and mentoring the next generation of leaders.

Phil Reid Managing Director J+S-Subsea

Phil Reid

Managing Director

Phil has worked in the energy industry for over 25 years. He started his career with Kvaerner FSSL progressing through a variety of roles in subsea engineering, from manufacturing to leading some of their most complex projects all over the world. He worked with the original J+S for a period before moving on to Genesis Oil and Gas as a Subsea Controls Engineering consultant; during that period, he was seconded to Centrica Energy (now Spirit Energy) which led to a permanent role as Lead Subsea Controls & Umbilical Engineer for Developments, Capital Projects and Operated Assets. For almost a decade Phil successfully delivered Capital Projects from concept right through to project close out whilst also looking after the running of their subsea assets.

As part of J&S Subsea limited, Phil oversees the day-to-day operations and will grow the business both in the UK and globally. 

James Morris

Engineering Director

James’s career started when he joined the Royal Navy from school as an Artificer Apprentice. After a 5-year Marine Engineering Apprenticeship he served in surface ships HMS Glamorgan, HMS Edinburgh, and HMS Glasgow and at Rosyth as part of an engineering support team. 

Moving into the Energy Industry in 1992, over the next 26 years he gained a wealth of experience within large and small companies on operation, design and project management of subsea control systems and equipment. This period started with several years as a Project Engineer for a family run hydraulic services company Grampian Hydraulics followed by 5 years as a Support Engineer at Kvaerner Oilfield Products.  James joined RRC Controls Services ltd in 2001 before finally moving to J+S Ltd in 2010. At J+S his dedication and technical capabilities were rewarded with several promotions until becoming a member of the management buyout team. 

He has designed an extensive array of subsea equipment from basic cable penetrators to complete subsea control modules. 

James thrives on providing solutions for client’s problems. 

As Engineering Director, James will ensure that the company provides clients with timely, cost effective and technically sound solutions and services. 

Matthew Blair

Executive Chairman

Matt Blair is Executive Chairman of J+S Subsea which was formed in October 2020 through a management buyout of the Subsea Engineering Division of Systems Engineering and Assessment Ltd.

With J+S Subsea and SEA for over 14 years, Matt has a wealth of industry knowledge and expertise.

Previously an Electronics Engineer with Ferranti Computer Systems Ltd specializing in sonar and submarine command systems, Matt moved into hydrographic survey working with Subsea7, Tritech, and CDL before joining J+S Subsea.

He was Vice Chair of the Decom Leadership Group of Decommission and in that role, he facilitated industry and academic studies on potential for reuse and repurposing of decommissioned equipment. He is still actively involved with the reuse agenda through Decommission and OEUK.

Although not part of day-to-day operations, Matt stays close to company strategic matters and is seeking further opportunities to update and transfer Energy technologies and products into the Marine Renewables markets and help to develop the broader circular economy.

Contact Us

  • J&S Subsea Limited
  • The Lombard Centre
  • Kirkhill Place
  • Dyce
  • AB21 0GU
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