How to Choose Submarine Cables: Types, Specs and Installation Guide

Submarine cables are among the most important components of modern global infrastructure. They support international communications, offshore renewable energy systems, cross-border power transmission, offshore oil and gas platforms, and global internet connectivity. Without undersea cables, modern telecommunications networks and international electrical systems would not function efficiently.

Today, submarine cables are used in a wide range of applications, including submarine power cable systems for offshore wind farms and fiber submarine cable networks for international data transmission. As offshore energy development and digital infrastructure continue expanding, selecting the correct submarine cable has become increasingly important for utilities, EPC contractors, telecommunications operators, and marine engineering firms.

Subsea cables operate in one of the harshest environments on Earth. They must withstand:

• High water pressure
• Corrosive marine environment exposure
• Mechanical stress
• Seabed movement
• Fishing activities
• Anchor impact risks
• Long-distance electrical or optical transmission demands

Modern cable design, therefore, requires a careful balance between electrical performance, mechanical protection, corrosion resistance, thermal management, and installation feasibility.

1. What Are Submarine Cables?

Submarine cables are specialized cables installed underwater to transmit electrical power or communication signals between offshore and onshore locations.

They are commonly categorized into:

• Submarine power cable systems
• Submarine communication cables
• Fiber submarine cable systems

Main Applications of Subsea Cables

Modern subsea cables are used in:

• Offshore wind farms
• International power interconnections
• Offshore oil and gas facilities
• Data transmission networks
• Island power supply systems
• Telecommunications infrastructure

Why Submarine Cables Are Critical

Submarine cables connected between countries and offshore facilities support:

• Global internet traffic
• Renewable energy transmission
• International electrical trade
• Offshore industrial operations

Over 95% of international internet data is transmitted through submarine fiber cable systems rather than satellites.

2. Main Types of Submarine Cables

Different underwater applications require different cable technologies.

Comparison of Main Types of Submarine Cables

Submarine Power Cable

Submarine power cable systems transmit electrical energy underwater.

These cables are widely used for:

• Offshore wind farms
• Island electrification
• Cross-border grid interconnections

HVAC vs HVDC Submarine Power Cable

HVAC Cables

High-voltage alternating current cables are suitable for shorter transmission distances.

Advantages include:

• Simpler converter systems
• Lower terminal equipment cost

HVDC Cables

High-voltage direct current submarine power cable systems are preferred for long-distance transmission.

Advantages include:

• Lower transmission loss
• Better efficiency over long distances
• Improved grid stability

Fiber Submarine Cable

Fiber submarine cable systems use fiber optic cables to transmit digital communication signals.

Applications include:

• Internet backbone infrastructure
• International telecommunications
• Cloud computing networks
• Data centers

Hybrid Submarine Cables

Modern cable design increasingly combines:

• Electrical conductors
• Fiber optic cables

inside one integrated submarine cable system.

3. What Are the Different Layers of a Submarine Cable?

One of the most common engineering questions is:

What are the different layers of a submarine cable?

Modern submarine cables use multiple protective layers to survive underwater conditions.

Main Layers Inside a Modern Submarine Cable

Core Conductor or Optical Fiber

The central section contains either:

• Copper or aluminum conductors
• Fiber optic cables

Depending on the cable function.

Insulation Layer

Electrical submarine power cable systems use insulation materials such as:

• XLPE
• EPR
• Mass impregnated insulation

to prevent electrical leakage.

Water Blocking Layer

Water blocking materials prevent moisture penetration if the cable is damaged.

Metallic Shield

Metallic shielding improves:

• Electromagnetic protection
• Fault current handling

Steel Wires Armoring

Steel wires provide mechanical protection against:

• Fishing equipment
• Anchors
• Seabed abrasion
• Mechanical impact

Armoring is especially important in shallow water installations.

Outer Protective Sheath

The outer jacket protects against:

• Corrosion
• UV exposure
• Marine organisms
• Abrasion

4. Key Technical Specifications for Submarine Cable Selection

Proper submarine cable selection requires a detailed technical evaluation.

Voltage Rating

Submarine power cable systems may operate from:

• Medium voltage
• High voltage
• Ultra-high-voltage levels

depending on transmission requirements.

Current Carrying Capacity

Cable sizing depends on:

• Load demand
• Transmission distance
• Thermal dissipation
• Seabed conditions

Mechanical Strength

Subsea cables experience:

• Tensile loads
• Bending stress
• Installation stress

Cable design must support installation and long-term reliability.

Fiber Count and Bandwidth

For submarine fiber cable systems, engineers evaluate:

• Fiber count
• Data transmission capacity
• Future expansion requirements

Corrosion Resistance

The marine environment accelerates corrosion.

Protective materials must withstand:

• Saltwater exposure
• Biological activity
• Long-term immersion

5. Submarine Cable Installation Guide

Submarine cable installation is one of the most technically challenging marine engineering operations.

Route Survey and Planning

Every cable project begins with seabed analysis.

Engineers evaluate:

• Water depth
• Geological conditions
• Fishing activity
• Shipping routes
• Environmental restrictions

Planned cables must avoid unstable seabed regions.

Cable Laying Vessels

Specialized vessels install submarine cables using controlled tension systems.

Deep-sea they are laid directly onto the seabed in many offshore projects.

Cable Burial

In shallow waters, submarine cables are often buried beneath the seabed for protection.

Burial methods include:

• Jet trenching
• Mechanical plowing
• Directional drilling

Common Submarine Cable Installation Methods

Jointing and Termination

Long submarine cables require precision cable joints.

Poor joint quality is one of the leading causes of submarine cable failure.

Installation Instructions and Monitoring

Modern installation instructions include:

• Tension monitoring
• Bend radius control
• Weather analysis
• Real-time positioning systems

6. Challenges in the Marine Environment

Submarine cables operate in extremely difficult conditions.

Corrosion Risks

Saltwater exposure accelerates corrosion of metallic components.

Advanced coatings and armored layers improve durability.

Mechanical Damage

Common external threats include:

• Ship anchors
• Fishing trawlers
• Seabed movement
• Earthquakes

Thermal Management

High-voltage submarine power cable systems generate heat during operation.

Seabed thermal conductivity affects cable ampacity.

Deep-Sea Pressure

Deep-sea cable systems must withstand enormous hydrostatic pressure.

The cable structure must prevent deformation and water ingress.

Table: Submarine Cable Failure Risks and Protection Methods

7. How to Choose the Right Submarine Cable

Choosing the correct submarine cable depends on operational and environmental requirements.

For Offshore Wind Farms

Recommended features include:

• High voltage transmission capability
• Strong mechanical armoring
• Long operational lifespan

For Telecommunications Networks

Fiber submarine cable systems should prioritize:

• Low signal attenuation
• High bandwidth
• Long-distance reliability

For Harsh Marine Environments

Engineers should evaluate:

• Steel wires armoring
• Corrosion protection
• Impact resistance

Important Engineering Selection Factors

Key considerations include:

• Transmission distance
• Voltage level
• Installation depth
• Seabed conditions
• Mechanical protection
• Future maintenance accessibility

8. Future Trends in Submarine Cable Technology

Global submarine cable demand continues to increase rapidly.

Offshore Renewable Energy Expansion

Offshore wind projects are driving massive demand for submarine power cable infrastructure.

Higher Capacity Fiber Networks

Modern submarine fiber cable systems now support:

• AI data centers
• Cloud computing
• 5G infrastructure

Smart Cable Monitoring

Advanced submarine cables are increasingly used:

• Real-time temperature monitoring
• Distributed sensing systems
• Predictive maintenance technologies

Improved Sustainable Materials

Future cable design focuses on:

• Lower environmental impact
• Improved recyclability
• Longer service life

FAQ: Submarine Cables

1. What are submarine cables used for?

Submarine cables are used to transmit electrical power or communication data underwater between offshore facilities, islands, countries, and continental regions. They support offshore wind farms, internet infrastructure, telecommunications systems, and international power transmission networks.

2. What is the difference between a submarine power cable and a fiber submarine cable?

Submarine power cable transmits electrical energy using copper or aluminum conductors, while fiber submarine cable transmits digital communication signals using optical fiber technology for internet and telecommunications networks.

3. What are the different layers of a submarine cable?

A modern submarine cable typically includes a conductor or optical core, insulation layer, water blocking layer, metallic shield, steel wires armoring, bedding layer, and outer protective sheath to ensure electrical performance and mechanical protection in the marine environment.

4. Why are steel wires used in submarine cables?

Steel wires are used for armoring and mechanical protection. They help submarine cables resist fishing equipment impact, anchor damage, seabed abrasion, tensile stress, and harsh underwater installation conditions.

5. How are submarine cables installed underwater?

Submarine cables are installed using specialized cable-laying vessels. Depending on seabed conditions and project requirements, cables may be directly laid on the seabed, buried using jet trenching or plowing methods, or protected with rock placement systems.

6. What factors should be considered when choosing submarine cables?

Important selection factors include voltage level, transmission distance, marine environment conditions, cable design, corrosion resistance, mechanical protection, installation depth, thermal performance, and future maintenance accessibility.

Conclusion

Submarine cables form the backbone of modern global communication and energy infrastructure. Whether used for submarine power cable systems or fiber submarine cable networks, these specialized undersea cables must operate reliably in some of the harshest environments on Earth.

Successful submarine cable project development requires careful evaluation of voltage levels, cable design, installation methods, environmental conditions, and long-term operational reliability. Factors such as mechanical protection, steel wire armoring, corrosion resistance, thermal performance, and seabed conditions all significantly affect system lifespan and performance.

As offshore renewable energy, global internet traffic, and international power interconnections continue expanding, advanced submarine cables will remain essential technologies supporting the future of worldwide energy and communication systems.