Fiber optic special-purpose tether for underwater drone — subsea electro-optical hybrid cable combining single-mode or multi-mode optical fibres with power conductors. Depth-rated construction, SS tube or Xtreme-Light fibre elements, Kevlar strength. Supports ROV, AUV, drone tether, and offshore EO systems.
This Fiber optic special-purpose tether for underwater drone combines optical fibres and copper power conductors in a single ruggedised subsea cable assembly. By transmitting data via optical fibres, the cable achieves bandwidth and latency performance impossible with copper-only designs — supporting 4K HD video streaming, real-time sensor fusion, and fibre-optic gyroscope (FOG) navigation data at any operational depth.
Fibre elements are protected in either precision stainless steel (SS) buffer tubes for maximum crush resistance, or ultra-compact 4.6 mm diameter Xtreme-Light® simplex constructions for minimum diameter and weight. Power conductors range from 22 AWG signal levels to 10 AWG / 3.6 kV for high-voltage umbilical applications. Strength members of Kevlar®, Twaron®, or Vectran® provide tensile load capacity matched to the deployment scenario.
| Parameter | Specification |
|---|---|
| Fibre Types | Single-mode (SMF-28e), Multi-mode (OM1/OM2/OM3), or mixed |
| Fibre Count | 1 to 6 per element; multiple elements combinable (1–24 total fibres) |
| Fibre Element OD | 4.6 mm (Xtreme-Light simplex); SS-tube per design |
| Attenuation (SM) | <0.35 dB/km @ 1,310 nm; <0.20 dB/km @ 1,550 nm |
| Power Voltage | 300V / 600V / 1,000V / 3,600V |
| Power Conductor AWG | 22 AWG to 6 AWG (10 AWG standard for 3.6 kV) |
| Break Strength | 2,700 lbs (Kevlar light tether) to 4,000+ lbs; steel armour to 180,000 lbs |
| Jacket | Xtreme-grade PUR 90°C; or Hytrel® / HDPE for tow cables |
| Temperature | -25°C to +90°C operating |
| Depth Rating | Standard: 6,000 m; deep armoured: full ocean depth (11,000 m custom) |
| OD Range | 7 mm (micro-tether) to 45 mm (heavy umbilical) |
Copper Ethernet cables suffer capacitance increase under pressure, limiting practical data rates and cable lengths. Single-mode optical fibre is immune to pressure effects — attenuation and bandwidth remain constant from the surface to full ocean depth, supporting 10 Gbps and beyond regardless of cable length or depth.
High-voltage ROV thrusters, powerful LED lighting systems, and electric manipulators generate significant EMI that degrades copper Ethernet performance. Optical fibres carry photons, not electrons — they are completely immune to electromagnetic interference and ground loops, ensuring clean data even adjacent to 3.6 kV motor cables.
A 3 SM fibre + 3× 10 AWG EO hybrid cable achieves 2,700 lbs break strength at an OD of under 16 mm (0.63") — far more compact than an equivalent all-copper design carrying the same data and power payload. Reduced diameter means lower hydrodynamic drag and longer tether operability in currents.
As ROVs grow in capability and power demand, 24V and 48V tether systems give way to medium-voltage umbilicals. Our 3.6 kV rated EO cables enable efficient power transmission over long tether lengths with minimised I²R losses — the same approach used in full-scale offshore umbilical systems, now available in compact tether diameters.
Stainless steel buffer tubes provide maximum crush resistance for armoured tow cables and heavy umbilicals where external mechanical stress is high. Xtreme-Light simplex elements save weight and OD in dynamic tether applications where the cable undergoes continuous bending on the ROV drum.
| Configuration | Fibres | Power | Voltage | BS (lbs) | OD (in) |
|---|---|---|---|---|---|
| EO Hybrid Light | 3× SMF simplex | 6× 22AWG | 600V | 2,700 | 0.292 |
| EO Hybrid Medium | 3× SMF simplex | 3× 14AWG | 600V | 2,700 | 0.595 |
| EO Hybrid HV | 3× SMF simplex | 3× 10AWG | 3,600V | 4,000 | 0.640 |
| EO Hybrid HV-8AWG | 3× SMF simplex | 3× 8AWG | 3,600V | 4,000 | 0.670 |
| Armoured umbilical | 6× MM SS-tube | 6× 18AWG + 4× 12–14AWG | 600V | 18,000 | 1.025 |
| Flat composite | 1–4× SM | 2–4 Cu pairs | 600V | 2,000+ | Flat profile |
| Micro tether | 1–2× SM simplex | 2–4× 20AWG | 300V | 1,000+ | 0.350–0.550 |
Optical fibres require a minimum bend radius of 30 mm (short-term) and 50 mm (long-term permanent installation). During cable preparation for connector termination, protect bare fibre from mechanical shock, contamination, and contact with cutting tools. Use appropriate fibre cleavers and fusion splicers for low-loss permanent joints; use factory-polished field-installable connectors for surface deployments only.
EO hybrid cables require level-wind spooling mechanisms to prevent point-loading of fibre elements during fast deployment. Drum flanges must clear the cable OD by a minimum of 3× to prevent edge crush. Rotary optical joints (ROJ) or fibre swivels are recommended for continuously rotating drum systems — standard slip-rings are for copper only and will break optical fibres.
Before deep deployment, conduct an OTDR (Optical Time Domain Reflectometry) baseline measurement on all fibre elements. Record the trace for comparison after each major deployment. Any increase in reflectance events or step-losses indicates fibre damage from mechanical stress. Electrical Hi-Pot testing of power conductors at 1.5× rated voltage verifies insulation integrity before submersion.
Specify fibre count and type (SM/MM), power voltage and AWG, break strength, depth rating, OD target, and deployment method — we engineer the exact EO hybrid cable for your ROV, AUV, or offshore application.
Custom designs | SM/MM/mixed | 600V to 3,600V | Global delivery
