Tokyo Keiki TG-8000 & TG-6000 Gyrocompass Service

BLUF: MarineListing provides 24/7 Class-certified engineering attendance, gyrosphere replacement, inverter PCB repair, and annual calibration for Tokyo Keiki (formerly Tokimec) TG-8000, TG-8100, TG-8500, TG-8600, and TG-6000 marine gyrocompass systems globally. Compliant with IMO Res. A.424(XI), ISO 8728, and SOLAS Chapter V Regulation 19, our certified Marine Navigation Engineers perform complete mechanical and electronic overhauls, supporting liquid renewals, slip ring polishing, optical encoder alignments, and NMEA/step repeater integrations across Singapore, Rotterdam, Dubai, Fujairah, Houston, Busan, and Shanghai.

1. Statutory Mandates, Classification Rules & Class Survey Rigor

SOLAS Chapter V Regulation 19 mandates that all ships of 500 gross tonnage and upwards must be fitted with a gyrocompass capable of determining the ship’s heading in relation to true geographic north, transmitting heading data to radar, ECDIS, AIS, and VDR systems. Statutory performance standards are governed by IMO Resolution A.424(XI) and ISO 8728 (Shipborne Gyro-Compasses). A malfunctioning gyrocompass or erratic heading transmission constitutes a major deficiency leading to immediate Port State Control (Paris MoU, Tokyo MoU, USCG) vessel detention.

+----------------------------------------------------------------------------------------------------+
|                         STATUTORY MARINE GYROCOMPASS REGULATORY FRAMEWORK                          |
+----------------------------------------------------------------------------------------------------+
|  SOLAS Chapter V, Reg 19        --> Carriage Requirements for Shipborne Navigational Equipment     |
|  IMO Resolution A.424(XI)       --> Performance Standards for Marine Gyro-Compasses                |
|  ISO 8728:2014                  --> Ships & Marine Technology - Marine Gyro-Compasses              |
|  IEC 61162-1 / NMEA 0183        --> Digital Interfaces for Marine Navigational Equipment           |
|  IEC 60945                      --> Environmental Testing of Marine Navigation Equipment           |
|  IACS Safety Navigation Survey  --> Annual Performance Verification of Primary Heading Sensor      |
+----------------------------------------------------------------------------------------------------+

Statutory Performance Tolerances (IMO Res. A.424(XI) & ISO 8728)

• Settling Time:
  • Must settle within $\le 6.0\text{ hours}$ from cold start when initiated within $\pm 30^\circ$ of true meridian.
• Settled Heading Error:
  • Settle point error must not exceed $\le \pm 0.75^\circ \times \sec(\text{Latitude})$.
  • Repeatability error between consecutive settling sequences: $\le \pm 0.25^\circ$.
• Dynamic Motion & Follow-Up Error:
  • Maximum follow-up lag under vessel turning rate of $6^\circ/\text{sec}$: $\le 0.5^\circ$.
  • Dynamic error under heavy rolling and pitching ($20^\circ$ amplitude, $10\text{ sec}$ period): $\le \pm 1.0^\circ$.

Classification Society Compliance Matrix

2. Engineering Architecture & Gyrodynamic Physics

Tokyo Keiki TG-8000 and TG-6000 systems utilize a hermetically sealed, fluid-suspended Gyrosphere driven by a high-speed 3-phase asynchronous motor ($12,000\text{ RPM}$) enclosed within an inner gimbal ring and suspended in conductive supporting fluid.

+----------------------------------------------------------------------------------------------------+
|                         TOKYO KEIKI TG-8000 GYROCOMPASS ARCHITECTURE                               |
+----------------------------------------------------------------------------------------------------+
|                                                                                                    |
|    [ 24V DC / 115V AC Power Supply ] ──► [ Inverter Driver Board (3-Phase 115V AC, 400 Hz) ]       |
|                                                               │                                    |
|                                                               ▼                                    |
|                                            [ Sensitive Element: TG-8000 Gyrosphere ]               |
|                                            ├── 12,000 RPM High-Speed Dual Rotor                    |
|                                            ├── Supporting Fluid (SG = 1.025 @ 20°C)                |
|                                            └── Concentric Platinum Slip Rings                      |
|                                                               │                                    |
|                                                               ▼                                    |
|                                            [ Optical Azimuth Follow-Up Pick-Off ]                  |
|                                                               │                                    |
|                                                               ▼                                    |
|                                            [ Digital Signal Processor (DSP) Master PCB ]           |
|                                                               │                                    |
|                     ┌─────────────────────────────────────────┼────────────────────────────────┐   |
|                     ▼                                         ▼                                ▼   |
|         [ NMEA 0183 / IEC 61162-1 ]                 [ Step Output (24V/35V) ]        [ Alarm Contacts ]|
|         ($--HDT, $--THS, 38400 baud)                 (To Wing Repeaters & RADAR)      (Fail-Safe Relays)|
|                                                                                                    |
+----------------------------------------------------------------------------------------------------+

Gyroscopic Precession & Meridian Seeking Mechanics

The gyroscopic angular momentum ($H = I \cdot \omega$) reacts to Earth's rotation rate ($\Omega = 7.292 \times 10^{-5}\text{ rad/s}$) and vessel latitude ($\phi$). The controlling torque ($T_c$) generated by internal pendulous weights creates North-seeking precession:

$$\text{Precession Rate:} \quad \omega_p = \frac{T_c}{H} = \frac{m \cdot g \cdot r \cdot \sin(\theta)}{I \cdot \omega}$$

$$\text{North-Seeking Period:} \quad T_{\text{Schuler}} = 2\pi \sqrt{\frac{R_{\text{Earth}}}{g}} \approx 84.4\text{ minutes}$$

Latitude and Speed Error Compensation

Vessel speed ($V$ in knots) and course ($C$) induce a dynamic speed error ($\delta_{\text{speed}}$) that must be mathematically corrected by the Tokyo Keiki DSP processor:

$$\delta_{\text{speed}} = \frac{V \cdot \cos(C)}{900 \cdot \pi \cdot \cos(\phi)} \quad (\text{radians}) \approx \frac{V \cdot \cos(C)}{49.43 \cdot \cos(\phi)} \quad (\text{degrees})$$

Where:

• $V$ = Vessel speed over ground (knots).
• $C$ = True course over ground (degrees).
• $\phi$ = Ship's latitude (degrees).

3. 5-Stage Standard Operating Procedure (SOP) for System Servicing

+----------------------------------------------------------------------------------------------------+
|                         TOKYO KEIKI TG-8000 5-STAGE OVERHAUL SOP                                   |
+----------------------------------------------------------------------------------------------------+
|  [STAGE 1: ISOLATION]  --> Switch steering to magnetic, lockout power, record repeater offsets    |
|  [STAGE 2: EXTRACTION] --> Syphon supporting liquid, unclamp gyrosphere, inspect container bowl    |
|  [STAGE 3: OVERHAUL]   --> Polish slip rings, replace horizontal shaft bearings, renew gaskets    |
|  [STAGE 4: REFILL]     --> Fill fresh supporting liquid (SG 1.025), de-aerate, balance sphere     |
|  [STAGE 5: COMMISSON]  --> Spin-up 12,000 RPM, settle test, NMEA string audit, Class certification|
+----------------------------------------------------------------------------------------------------+

Stage 1: Navigational Isolation & Bridge Notification

1. Inform the Officer of the Watch (OOW); switch autopilot and steering gear to Secondary Heading / Magnetic Compass follow-up.
2. Record initial heading values and mechanical repeater alignments on bridge wings and steering console.
3. Power down the master gyro unit and discharge inverter filter capacitors.

Stage 2: Gyrosphere Extraction & Fluid Drain

1. Open the master compass bowl cover; extract the old supporting and contact liquids using clean syphon apparatus.
2. Lift the sensitive gyrosphere element using dedicated Tokyo Keiki extraction brackets; place on a cushioned bench stand.
3. Inspect container bowl walls and electrode pins for copper pitting, galvanic discoloration, or particulate contamination.

Stage 3: Mechanical Overhaul & Inverter PCB Calibration

1. Clean and polish platinum contact slip rings using non-abrasive micro-mesh; replace carbon brushes if worn $> 2.0\text{ mm}$.
2. Replace horizontal gimbal support bearings, damping oil pots, and upper/lower bowl O-ring gaskets.
3. Power the inverter drive PCB on the test bench; verify 3-phase 115V AC output at exactly $400.0\text{ Hz} \pm 0.5\text{ Hz}$.

Stage 4: Flotation Fluid Refill & Specific Gravity Calibration

1. Fill the container with genuine Tokyo Keiki supporting liquid (Part No. 10165037).
2. Measure fluid specific gravity with a temperature-compensated hydrometer: target is $1.025 \pm 0.002$ at $20.0^\circ\text{C}$.
3. Lower the gyrosphere into the fluid; check sphere flotation depth ($h_{\text{float}} = 4.0 - 5.0\text{ mm}$ clearance between sphere equator and bowl rim).
4. Remove all micro air bubbles using a vacuum degassing pump.

Stage 5: Spin-Up, Settling Verification & Class Endorsement

1. Power up the master gyrocompass; monitor 3-phase motor rotor run-up current ($I_{\text{start}} \approx 2.5\text{A} \to I_{\text{run}} \approx 0.75\text{A}$).
2. Allow the gyrocompass to undergo Schuler oscillation damping and settle on true meridian ($t_{\text{settle}} \le 4.0\text{ hours}$).
3. Align the optical rotary encoder zero point; verify digital IEC 61162-1 $HEHDT and $HETHS sentences at $38,400\text{ baud}$ to ECDIS, RADAR, AIS, and VDR.
4. Synchronize all step/synchro bridge wing repeaters; issue official Class Gyrocompass Annual Survey Certificate.

4. Diagnostics, Trouble Codes & Troubleshooting Matrix

+----------------------------------------------------------------------------------------------------+
|                    TOKYO KEIKI TG-8000 / TG-6000 ERROR CODES & DIAGNOSTICS                         |
+----------------------------------------------------------------------------------------------------+
|  Alarm Code | Diagnostic Description                 | Root Cause & Corrective Action              |
+-------------+----------------------------------------+---------------------------------------------+
|  ERR 01     | Gyro Motor Inverter Power Failure      | Inverter PCB blown fuse / IGBT fault.       |
|  ERR 02     | Gyro Motor Current Overload (> 1.5A)   | Rotor bearing seized; replace gyrosphere.   |
|  ERR 03     | Optical Follow-Up Servo Alarm          | Step motor fault, optical slit dirty/offset |
|  ERR 04     | Supporting Liquid High Temp (> 60°C)   | Cooling fan seized or high ambient temp.    |
|  ERR 05     | Supporting Liquid Level Low            | Fluid leakage through lower bowl seal.      |
|  ERR 08     | Step Data Transmission Failure         | Step driver board transistor open circuit.  |
|  ERR 10     | Heading Drift / Settling Abnormality   | Specific gravity incorrect / bubble trapped.|
+----------------------------------------------------------------------------------------------------+

5. Equipment Matrix & Technical Specifications

6. Global Port Attendance Corridors

Our factory-certified Marine Gyrocompass Specialists maintain 24/7 attendance across all major maritime straits and ports:

7. Frequently Asked Questions (FAQ)

What is the recommended overhaul interval for a Tokyo Keiki TG-8000 gyrocompass?

Manufacturer guidelines and IACS Class societies recommend an annual inspection every 12 months and a major overhaul with replacement of the supporting liquid and gaskets every 24 to 36 months ($20,000 - 25,000$ operating hours). The gyrosphere sensitive element typically operates reliably for 5 years before scheduled factory reconditioning.

What is the correct specific gravity for Tokyo Keiki supporting liquid?

The specific gravity of genuine Tokyo Keiki supporting liquid must be maintained at $1.025 \pm 0.002\text{ g/cm}^3$ at $20.0^\circ\text{C}$. Incorrect specific gravity causes the gyrosphere to sink or float excessively, generating severe heading drift errors and Error 10 alarms.

Can a Tokyo Keiki TG-8000 replace an older TG-5000 or TG-6000?

Yes. Tokyo Keiki manufactures direct retrofit kits that allow seamless replacement of legacy TG-5000 or TG-6000 gyrocompasses with modern TG-8000 systems, utilizing existing cabling, step repeater lines, and mounting footprints while upgrading serial IEC 61162-1 data outputs.

8. Structured Data & Class Approvals (JSON-LD)