Subsea operations are expanding rapidly, from offshore energy and marine science to defense and security. No matter the mission, one component often determines whether a project succeeds or fails: the subsea cable. Far more than just a connection, it transmits power, data, and control, while also carrying mechanical loads in harsh and unpredictable environments. Selecting the right cable is not simply a technical decision; it is a strategic one.
Introduction
Every subsea system is only as strong as its weakest link. Cables may represent a small part of the overall system, but they are essential for performance, safety, and reliability. A cable that is too short, too heavy, or unsuited to the environment can compromise the entire operation, whether it involves geophysical surveys, defense applications, offshore energy, or subsea robotics. This guide explains how subsea cables are designed and selected to be truly fit for purpose. Drawing on the latest industry developments, it explores trends, construction principles, system requirements, and approaches that extend lifespan and minimize downtime.
1. Subsea trends and their impact on the cable
1.1 Deeper operations
Longer, stronger cables are needed to reach greater depths and withstand high pressures. Beyond 4,000 meters, traditional steel becomes impractical, requiring lighter alternatives such as aramid fibers, which reduce weight but introduce new challenges for heat and fatigue.
1.2 Reducing downtime
Downtime is costly, whether for defense readiness, offshore energy, or survey efficiency. Advances in inspection, fiber-optic monitoring, and even self-healing materials are changing how we predict failures and extend service life.
1.3 Sustainability & energy transition
Renewable energy, offshore wind, CCUS, and emerging ocean technologies demand dynamic, long-lasting cables that can withstand motion, bending, and extreme weather , while reducing environmental impact.
2. Cable construction principles
Each subsea mission has unique requirements. A cable is typically built from:
- Conductors (usually copper) to transmit power.
- Optical fibers to ensure fast, reliable data transfer.
- Strength members (steel or aramid) to carry load.
- Sheathing and insulation for protection against pressure and mechanical stress.
Geometry, lay length, and materials determine how a cable balances flexibility, strength, and fatigue resistance. The goal: a design that protects fragile elements while ensuring reliable operation under load.
3. Fit-for-purpose design: linking system and cable requirements
System requirements translate directly into cable design. Critical factors include:
- Function: power, data, control, or hybrid.
- Deployment: winch type, bend radius, handling system.
- Depth: pressure, voltage drop, and required length.
- Power: heat management, insulation, electrical stress.
- Downtime & lifecycle: repairability, redundancy, fatigue resistance.
- Budget: cost versus reliability, avoiding “cheap choices” that prove expensive later.
4. Reliability, downtime, and life expectancy
Subsea cables are among the most fragile system components, but downtime can be prevented through:
- Redundancy (e.g., extra optical fibers).
- Smart protection (placing fragile components at the core).
- Repairability by design (steel armor is easier to re-terminate at sea than aramid).
- Careful fatigue modeling to balance tensile strength and flexibility.
5. DeRegt as Strategic Partner
A cable supplier delivers components. A strategic partner co-creates solutions. At DeRegt, we combine engineering expertise with field service, training, and long-term support. Our approach includes:
- Early Supplier Involvement: solving challenges from the design phase.
- Thinking Along: translating mission requirements into robust cable designs.
- Co-Creation: working with operators, engineers, and defense teams to deliver solutions built for success.
This partnership model means fewer delays, safer operations, and cables that continuously evolve with operational feedback.
Conclusion
Subsea cables may seem like a single component within a larger system, but their impact on uptime, safety, and mission performance is decisive. By aligning design with operational requirements, anticipating environmental challenges, and working closely with experienced partners, operators across energy, defense, and security achieve greater reliability, longer service life, and mission success.
