Technical Specification

1. Performance:

• Accuracy (Steady State):
  • Static (in still water): ±0.1∘ True North.
  • Dynamic (under maneuvering conditions): ±0.25∘ secant latitude (typically ±0.25∘ to ±0.5∘ depending on ship motion and latitude).
• Settling Time: Typically less than 4 hours from initial start-up, or less than 1 hour from stand-by.
• Stabilization Time: Typically less than 15-30 minutes for normal operation.
• Follow-Up Rate: Capable of following ship turns up to 100∘ per second (some specifications state higher, e.g., 180∘/sec).
• Latitude Correction: Manual or Automatic compensation for latitude up to 70∘ North/South.
• Speed Correction: Manual or Automatic compensation for vessel speed up to 60 knots.

2. Gyroscope Element:

• Type: Hermetically sealed gyrosphere, neutrally buoyant in silicone fluid.
• Rotor Speed: Typically 12,000 RPM (revolutions per minute) or higher.
• Rotor Power: High-frequency AC, often 200 Hz or 400 Hz.
• Suspension: Fluid ballistic (passive) and/or active control.
• Mounting: Three-gimbal system for full freedom of movement.

3. Outputs (Data Transmission):

• Step/Pulse Data: Multiple outputs for various gyro repeaters (e.g., 6 steps/degree, 36 steps/degree, 180 steps/degree).
• Serial Data (NMEA 0183):
  • Multiple RS-422 ports (e.g., 4-8 isolated ports).
  • Commonly transmits HDT (True Heading), HDG (Magnetic Heading – if interfaced with fluxgate), ROT (Rate of Turn).
  • Baud Rates: Configurable (e.g., 4800, 9600, 38400 bps).
• Analog Output: 1 dedicated analog output for Rate of Turn (ROT) (e.g., $\pm 10$ VDC for ±100∘/min).
• Synchro/Resolver Output: (Common in older systems, less so for new installations).
• Alarm Output: Potential-free contact for system malfunction alarm.

4. Power Supply:

• Main Supply: 115/230 VAC, 50/60 Hz, single phase.
• Standby/Emergency Supply: 24 VDC nominal (range 18-32 VDC).
• Power Consumption:
  • Start-up/Settling: Up to 300 W (peak).
  • Running: 100 – 180 W (typical).
• Automatic Power Changeover: Seamless transition from AC to DC standby power upon failure.

5. Physical Characteristics (Component-Dependent):

• Master Compass Unit (e.g., MK-37 Mod D Binnacle):
  • Dimensions: Approximately 600-700 mm (H) x 400-500 mm (Diameter) – varies greatly by mounting method.
  • Weight: Approximately 50-80 kg (including gyrosphere and fluid).
  • Mounting: Deck-mounted binnacle, shock-mounted.
  • Ingress Protection: Typically IP22 or higher, designed for internal mounting but robust.
• Control/Electronics Unit (e.g., MK-37 Mod E or VT Electronics Control Unit):
  • Dimensions: (Typically rack-mount or bulkhead mountable, e.g., approx. 19-inch rack width, 3-6U height).
  • Weight: 5-20 kg.
  • Ingress Protection: IP22 (protected indoor equipment).
• Display Assembly (for VT versions):
  • Dimensions: (Compact, designed for panel or console mounting).
  • Weight: A few kg.
  • Display: LCD or LED type.

6. Environmental Conditions:

• Operating Temperature: -15°C to +55°C (for internal components).
• Storage Temperature: -25°C to +70°C.
• Relative Humidity: Up to 95% at +40°C, non-condensing.
• Vibration & Shock: Compliant with IEC 60945 (for maritime navigation equipment).
• Electromagnetic Compatibility (EMC): Compliant with IEC 60945.

7. Key Features (Reiterated for Specification Context):

• Fluid Immersion & Neutral Buoyancy: Reduces friction, wear, and shock effects on gyrosphere bearings.
• Automatic Start/Stop: Allows for programmed power-up and shutdown.
• Self-Test & Diagnostics: Built-in test functions and alarm indicators for system status.
• Modular Design: Facilitates maintenance and component replacement.
• Optional Dual System Configuration: For redundancy (primary and secondary compasses).
• Repeaters: Compatible with a range of Sperry Marine and third-party analog and digital gyro repeaters.