What to check on a General Marine Cables.
8 models from Twin Disc in General Marine Cables. Below: the full model list.
What this category covers
Power distribution cable, rated 0.6/1 kV and similar classes, has its own listing. This general group is where the rest of a ship's cable plant sits: control and instrumentation cable carrying low-current signals between sensors and controllers, fibre optic cable carrying data for navigation and automation networks, coaxial cable for radar and communications antennas, and specialist types such as heating trace cable for tank and pipe frost protection. All of it is built to marine fire and mechanical standards, but none of it is chosen the way power cable is, because current-carrying capacity is not the limiting factor.
Legend
- Outer sheath
- Insulation (twisted pair)
- Overall screen (braided)
- Conductor
- Drain wire
- Filler
Read the full guide
Main types
Control and instrumentation cable
Multicore, often screened to keep electrical noise off a low-level signal, and sized by core count and screening rather than conductor cross-section, since the current involved is small.
Fibre optic cable
Carries data for integrated bridge systems, automation networks and increasingly for CCTV and IT backbones, immune to electromagnetic interference in a way copper cable is not, but needing a properly terminated connector and a minimum bend radius that a careless installation routinely violates.
Coaxial cable
Feeds radar, GPS, VHF and satellite communication antennas; signal loss over the cable run is a real design factor at the frequencies these systems use, so run length and cable grade are chosen together, not the cable alone.
Heating trace cable
Self-regulating or fixed-wattage electric heating cable wrapped along pipework carrying viscous fuel or cargo that must be kept above its pour point, controlled by a thermostat rather than run continuously.
Selection
Each type is selected on the parameter that actually limits it: screening effectiveness and core count for control cable, attenuation and connector compatibility for fibre and coaxial runs, and heat output per metre matched to pipe insulation for heating cable. Fire performance class still applies across all of them, following the same routing and segregation logic as power cable.
- Screening or armour appropriate to the electromagnetic environment the cable passes through, especially near high-power switchboards or thrusters
- Connector and termination compatibility confirmed before ordering fibre or coaxial cable, since a mismatched connector standard makes a correctly rated cable useless
- Heating cable output matched to the pipe's insulation and the lowest ambient temperature the ship actually trades in, not a generic figure
- Fire performance class consistent with where the cable is routed, same as any other shipboard cable
Regulations and class
The IEC 60092 series covers construction and fire testing for shipboard cable generally, including the control, instrumentation and low-power types in this group. SOLAS Chapter II-2 routing and segregation requirements apply here too, since a fibre backbone for the integrated bridge system still needs to survive a fire in the space it passes through if it serves a safety function. Heating trace cable installation is normally covered by the equipment manufacturer's certified installation method rather than a cable-specific class rule, since the hazard being managed is electrical, not structural.
Typical faults
| Cause | Consequence |
|---|---|
| Fibre bend radius violated during installation | Increased attenuation or fibre fracture, intermittent data faults that are hard to trace |
| Coaxial connector corrosion at an exposed antenna feed | Rising signal loss, degraded radar or communications range before outright failure |
| Control cable screen not earthed at both ends correctly | Noise pickup, false signals at the controller |
| Heating trace cable thermostat failure | Either no heat, risking a blocked line, or continuous heating and local overheating |
What to look for in a supplier
- Type approval to IEC 60092 for the specific cable type and fire performance class
- Connector and termination kits matched to the cable, sourced together rather than separately
- Technical support for fibre and coaxial link budget calculations, not just the cable itself
- Heating cable output curves referenced to the pipe sizes and insulation the ship actually uses
Log fibre optic attenuation at commissioning and check it again after any major refit - a link that still works can be running with far less margin than it had on day one, and a small further loss is what finally breaks it.