What the ETO owns here
When a superintendent or flag-state surveyor questions why a network run is unreliable, the ETO is expected to justify every cabling decision — length, route, cable type and termination. Guessing is not acceptable; the relevant standards are TIA-568 for channel geometry and IEC 60092-376 for shipboard cable construction.
The 90 m / 100 m rule (TIA-568)
TIA-568 limits horizontal twisted-pair cabling to 90 m of installed (permanent) link, leaving 10 m for patch cords at both ends combined. The full end-to-end path — permanent link plus patch cords — must not exceed 100 m. This is the channel length.
The current revision is ANSI/TIA-568-E.
Why does this matter on a yacht? Distances that look modest on a GA drawing accumulate fast once you follow a cable tray from a comms cabinet, up a mast trunk, across a deck head and down to a workstation. Always measure the actual routed length, not the straight-line distance — the two can differ substantially once the run is chased through trays, trunks and penetrations. If the installed link approaches the 90 m limit, patch cords leave almost no margin.
Exceeding the channel limit degrades signal integrity: attenuation increases, timing margins shrink, and at Gigabit speeds the link may train at a lower speed or drop entirely under load. The fix is always a switch or media converter at an intermediate point, never simply accepting a longer cable.
Shipboard cable standard — IEC 60092-376
IEC 60092-376 covers screened and unscreened control and instrumentation cables for fixed installation on ships and offshore units. These cables are constructed and tested to survive the shipboard environment: mechanical protection, flame retardance, low smoke and halogen emission, and resistance to oil, fuel and cleaning agents.
General-purpose commercial patch cable bought ashore is not an equivalent. It lacks the mechanical and fire performance required in a marine fixed installation. The ETO must specify and fit marine-grade cable for any permanent run — bulkhead penetrations, cable trays and inter-compartment routes in particular.
Explaining it to the crew
Most deck and interior crew encounter cabling only when something stops working. A practical briefing to a chief stewardess or bosun planning a refit job:
- "The maximum cable length from the switch to any socket is 90 metres of cable in the structure. Add the leads at each end and the total must stay under 100 metres."
- "We cannot use domestic patch cable inside the vessel's structure — regulations require marine-rated cable that resists fire and fumes."
- "If a new AV or data point is planned, tell me before the bulkheads are closed. Fitting a switch mid-route is straightforward; re-running cable through a finished deck is not."
Keep the message simple: length limits exist, marine cable is mandatory, and the ETO must be involved before installation, not after.