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Engine Telegraph and Remote Control on Marine Engines

Engine telegraph and remote control systems allow the bridge to command the engine room from the navigating bridge. Traditional telegraphs were mechanical or electric devices with discrete positions (Full Ahead, Half Ahead, Slow Ahead, Stop, Slow Astern, Half Astern, Full Astern), with the engine room responding by matching the same lever position. Modern ships have integrated bridge control with continuous bridge throttle directly controlling engine speed, integrated displays, and software-defined command authority. This article covers traditional telegraphs, modern bridge control, command transfer, integration with governor and safety systems, and operational considerations. Visit the home page or browse the calculator catalogue for related engineering tools.

Contents

Background

Communication between the bridge and the engine room has always been a fundamental requirement of ship operation. Early steamships used voice tubes (literal tubes carrying voice between bridge and engine room) and call bells for limited signalling. As engine power grew and ship complexity increased, dedicated engine telegraphs were developed: mechanical or electrical devices that conveyed specific engine commands between bridge and engine room.

The classical engine telegraph has lever positions corresponding to discrete engine states:

  • Full Ahead (typically 100% MCR)
  • Half Ahead (typically 70% MCR)
  • Slow Ahead (typically 35% MCR)
  • Dead Slow Ahead (typically minimum running speed)
  • Stop
  • Dead Slow Astern
  • Slow Astern
  • Half Astern
  • Full Astern

The bridge moves its lever to the desired position; a chime or buzzer alerts the engine room; the engine room operator moves their matching lever to the same position, both confirming receipt and verifying command intention.

Modern ships have largely replaced telegraphs with integrated bridge control systems that allow the bridge to directly control engine speed via a continuous throttle. The traditional telegraph remains as a backup and during certain operations.

This article covers traditional telegraph systems, modern bridge control, command transfer and authority, and the operational role of these systems.

Traditional engine telegraph

Mechanical telegraph

The earliest engine telegraphs were purely mechanical: a brass or bronze lever connected by chain or wire to a corresponding lever in the engine room. Movement of one moved the other; the engine room responded by acknowledging the position.

Mechanical telegraphs:

  • Robust and reliable
  • No external power required
  • Simple to maintain
  • Limited functionality (just position transfer)

Electric telegraph

Most twentieth-century ships used electric telegraphs:

  • Bridge lever operates an electrical switch or potentiometer
  • Engine room display shows the bridge command
  • Engine room lever operates a return display showing the response
  • Electrical chime indicates new commands

Electric telegraphs allowed:

  • Bridge wing telegraphs (multiple bridge stations)
  • Better display ergonomics
  • Sound and light alerts

Components

A typical electric telegraph system has:

  • Master telegraph: at the central bridge console
  • Wing telegraphs: at the bridge wings (port and starboard) for manoeuvring near pilot or pier
  • Engine room telegraph: in the engine control room
  • Sub-telegraph: at the engine itself for direct communication
  • Power supply: usually 24V DC battery-backed
  • Wiring: dedicated cabling between bridge and engine room

Modern integrated bridge control

Continuous throttle

Modern ships have integrated bridge control with a continuous throttle lever or wheel. The bridge sets a desired engine speed, transmitted to the engine via the engine control system which then commands the governor accordingly.

Continuous control allows:

  • Any speed within the operating envelope (not limited to discrete positions)
  • Smooth transitions during ramping
  • Immediate response to bridge command changes
  • Integration with autopilot and navigation systems

Combined throttle-pitch (CPP)

For ships with controllable pitch propellers, a single combined throttle controls both engine speed and propeller pitch. The control system manages the relationship between the two for optimal operation.

Throttle backup

Modern ships typically retain a traditional telegraph as backup, with mechanism to fall back to telegraph control if the primary integrated system fails.

Bridge displays

Modern bridges have extensive engine displays:

  • Engine speed and load indicators
  • Cylinder exhaust temperatures
  • Turbocharger speeds
  • Fuel consumption rates
  • Any active alarms or emergencies
  • Trend graphs of key parameters

The bridge effectively has a complete engine room view without leaving the navigation post.

Command authority

Bridge-Engine room dual authority

Traditional ships have dual control authority: both bridge and engine room can move the engine telegraph. Engine room can override bridge commands in emergencies (e.g. blocking a “Full Astern” if engine cannot safely reverse from current state).

Bridge-only authority

Modern integrated bridge control has bridge-only authority during normal operations. The engine room can intervene through:

  • Engine room emergency stop
  • Manual engine room control transfer
  • Direct override of specific functions

Pilotage

During pilotage (entering/leaving port, transiting confined waters), command authority may transfer:

  • Pilot at the bridge takes the helm and controls engine speed
  • Master and engine room remain prepared for emergency intervention
  • Command authority may be temporarily granted to the pilot

Position transfer

Commands can be transferred between control positions:

  • Bridge → Engine room: engine room takes manual control
  • Engine room → Bridge: bridge regains automatic control
  • Wing → Centre: bridge wing controls during manoeuvring, central console for sea passage

Position transfer is acknowledged by both stations, ensuring no ambiguity.

Integration with engine systems

Governor integration

The engine telegraph or bridge throttle commands the governor setpoint. The governor manages fuel quantity to achieve and maintain the commanded speed.

Reversing integration

Bridge commands “Astern” through the telegraph or throttle. The engine reversing system executes the reversal sequence:

  • Stop engine
  • Switch to astern timing maps
  • Restart in astern direction

The bridge sees the entire process; the engine takes appropriate time (typically 1-3 minutes).

Safety integration

Emergency stops from any control position:

  • Cut fuel immediately
  • Override any current command
  • Activate alarms

Safety system has highest authority, regardless of control position.

Telegraph response time

Telegraph commands have specific response time requirements:

  • Bridge command issued
  • Engine room acknowledgement within seconds
  • Engine action initiated within seconds
  • Engine response per its mechanical characteristics

For modern integrated bridge control, the chain is much faster: bridge throttle to engine response is typically a fraction of a second.

SOLAS requirements

The International Convention for the Safety of Life at Sea (SOLAS) prescribes minimum requirements for engine control systems:

  • Reliable bridge-engine room communication
  • Multiple control positions where appropriate
  • Safety systems independent of normal control
  • Visual and audible indication of commands
  • Regular testing and verification

These requirements are detailed in classification society rules and verified at survey.

Operational considerations

Command etiquette

Bridge commands follow specific protocols:

  • “Full Ahead” understood as full operational ahead, not maximum overload
  • “Half Ahead” at fixed RPM relative to full ahead
  • “Stop” requires clear understanding before action
  • Verbal communication accompanies telegraph for clarity

Pilotage handover

When a pilot boards:

  • Master briefs pilot on engine status, speed limits, response characteristics
  • Pilot takes helm and controls engine
  • Master remains in command of vessel
  • Engine room confirms readiness

When pilot disembarks:

  • Pilot returns control to master
  • Master verifies commands and resumes normal operation

Emergency commands

Specific emergency commands have agreed responses:

  • “Crash Stop”: fastest possible stop, all measures used
  • “Emergency Astern”: fastest possible reversal
  • “Stop Engine”: orderly stop with normal procedure
  • “Hard Astern”: maximum power astern

Crews drill these regularly so commands are understood and executed correctly.

Logging

All bridge engine commands are typically logged:

  • Telegraph position changes recorded
  • Throttle commands captured
  • Time-stamped for incident analysis
  • Available for post-event review

Logs are particularly important for incident investigation (groundings, collisions, equipment failures).

Modern developments

Networked control

Modern ships have computer networks connecting bridge, engine room, and other control points. Network-based control allows:

  • Multi-point displays
  • Distributed alarms
  • Integrated voyage planning
  • Remote support from shore

Voice integration

Some installations include voice communication integrated with engine control:

  • Bridge speaks command into headset
  • Voice recognition translates to throttle adjustment
  • Engine room speaks back
  • Reduces manual control burden

Automation

Higher levels of automation reduce manual control burden:

  • Autopilot integration with throttle
  • Automatic compensation for sea conditions
  • Coordinated propeller and rudder control
  • Automatic anti-grounding systems

These reduce the cognitive load on bridge teams during routine operations.

See also

References

  • SOLAS. (1974). International Convention for the Safety of Life at Sea, as amended.
  • IACS. (2018). UR M65: Bridge Control of Engine.
  • IMO. (1995). Resolution A.847(20): Guidelines for the Carriage of Marine Engine Telegraphs.
  • MAN Energy Solutions. (2023). Bridge Control Integration Manual. MAN Energy Solutions.
  • Lloyd’s Register. (2022). Marine Engine Bridge Control System Approval.