Aux 1 Unit 9 Q6

An electro-hydraulic steering gear is a type of steering system that combines the power of hydraulics with the precision and flexibility of electronic control. It’s a common choice for larger vessels, including superyachts, where reliable and responsive steering is critical.  

1. Ship Four Ram Steering Gear Explained – saVRee

Key Components:

• Hydraulic Power Unit (HPU): This unit generates and supplies pressurized hydraulic fluid to the system. It typically consists of:
  • Electric Motor: Drives the hydraulic pump.   1. Electro-Hydraulic Power Assisted Steering – Car Terms – SEAT www.seat.com
  • Hydraulic Pump: Pressurizes the hydraulic fluid.   1. Understanding the Differences Between Electric and Hydraulic Steering – Mevotech www.mevotech.com
  • Reservoir: Stores the hydraulic fluid.
  • Filters and Valves: Ensure the fluid’s cleanliness and control its flow.
• Actuators: These convert hydraulic pressure into mechanical force to move the rudder. Common types include:   1. Rudder actuator – Wärtsilä www.wartsila.com
  • Hydraulic Rams (Cylinders): Produce linear motion to push or pull the tiller or rudder stock.
  • Rotary Vane Actuators: Generate rotary motion to directly turn the rudder stock.
• Control System: This system receives steering commands from the helmsman and translates them into control signals for the hydraulic system. It typically includes:
  • Steering Wheel or Joystick: The input device used by the helmsman.
  • Electronic Control Unit (ECU): Processes the steering commands and generates control signals for the hydraulic system.
  • Sensors: Monitor the rudder’s position and provide feedback to the ECU for precise control and autopilot functionality.

Operation:

1. Steering Command: The helmsman turns the steering wheel or moves the joystick, generating a steering command.
2. Electronic Control: The ECU receives the steering command and processes it, determining the required rudder angle.
3. Hydraulic Actuation: The ECU sends control signals to the HPU, which activates the hydraulic pump and directs pressurized fluid to the appropriate side of the actuators.
4. Rudder Movement: The hydraulic actuators move, pushing or pulling the tiller or rotating the rudder stock, causing the rudder to turn.
5. Feedback: Sensors on the rudder provide feedback to the ECU on the actual rudder angle, allowing for continuous monitoring and adjustment to maintain the desired course.

Advantages of Electro-Hydraulic Steering Gear:

• High Power and Precision: Combines the high power density of hydraulics with the accuracy and flexibility of electronic control.
• Remote Control: Allows for steering control from multiple locations on the vessel through electronic control panels.   1. Electro-Hydraulic Steering Gear – Lloyds Engineering Works Ltd www.lloydsengg.in
• Autopilot Integration: Easily integrates with autopilot systems for automatic steering.   1. Electro-Hydraulic Steering Gear – Lloyds Engineering Works Ltd www.lloydsengg.in
• Redundancy: Can be designed with redundant components for increased reliability and safety.
• Compact Design: The use of electric motors and compact hydraulic components can result in a space-efficient system.   1. Steering Gear – Mitsubishi Heavy Industries, Ltd. Global Website www.mhi.com

Disadvantages:

• Complexity: More complex than purely hydraulic or electric systems, requiring specialized knowledge for maintenance and repair.
• Dependence on Electrical Power: Requires a reliable electrical power source for the control system and hydraulic pumps.
• Potential for Leaks: Hydraulic systems can develop leaks, requiring regular inspection and maintenance.

Applications:

• Widely used on various types of vessels, including superyachts, commercial ships, and naval vessels.   1. Steering Gear – Mitsubishi Heavy Industries, Ltd. Global Website www.mhi.com
• Particularly suitable for larger vessels requiring high power and precise steering control.

In Conclusion:

Electro-hydraulic steering gear systems offer a combination of power, precision, and flexibility, making them ideal for demanding marine applications. They enable accurate and responsive steering control, facilitate autopilot integration, and provide the necessary redundancy and safety features for large vessels operating in challenging environments.

Should the telemotor system fail on a vessel, steering control can still be maintained through several backup mechanisms designed to ensure the safety and maneuverability of the ship. These mechanisms primarily involve switching to alternative control methods and utilizing redundant systems. Here are some common approaches:

1. Non-Follow-Up (NFU) Mode:

• Direct Control: Many modern steering gear systems have a non-follow-up mode where the rudder can be directly controlled from the bridge using a separate set of controls, bypassing the telemotor system.   1. Marine Investigation Report M14C0045 – Transportation Safety Board of Canada www.tsb.gc.ca
• Manual Operation: This often involves manually adjusting hydraulic valves or operating electric motors to move the rudder.
• Limited Functionality: While NFU mode allows for basic steering control, it might not offer the same level of precision or responsiveness as the telemotor system, especially in challenging conditions.

2. Auxiliary/Emergency Steering Gear:

• Independent System: Larger vessels are often equipped with an auxiliary or emergency steering gear, a separate and independent system capable of operating the rudder in case of a main steering gear failure, including telemotor failure.
• Manual or Power-Assisted: This system can be manually operated using a hand pump or a dedicated steering wheel, or it might be power-assisted using a separate hydraulic power unit or electric motor.
• Reduced Capacity: The auxiliary steering gear might have a lower rudder speed or limited functionality compared to the main system, but it’s designed to provide enough control to maneuver the vessel safely to a port or sheltered location for repairs.

3. Local Control in the Steering Gear Compartment:

• Manual Operation: In some cases, the steering gear can be operated directly from the steering gear compartment using local controls, typically involving manual operation of hydraulic valves or other mechanisms.
• Communication with Bridge: This method requires clear and reliable communication between the bridge and the steering gear compartment to relay steering commands.
• Emergency Scenario: Local control is usually considered an emergency measure used when other options are unavailable.

4. Autopilot (Limited Functionality):

• Maintain Course: If the autopilot system is independent of the telemotor system, it might still be able to maintain the current course or heading even if the telemotor fails.
• No New Commands: However, the autopilot won’t be able to receive new course changes or commands from the bridge in case of telemotor failure.

Key Considerations:

• Crew Training: It’s vital that the crew is well-trained in the operation of all backup steering systems and emergency procedures to ensure a swift and effective response in case of a telemotor failure.
• Regular Testing and Maintenance: All steering systems, including the backup and emergency systems, should be regularly tested and maintained to ensure their readiness for operation.
• Communication: Clear and reliable communication between the bridge and the steering gear compartment is crucial, especially when relying on local control.

By having these backup mechanisms and procedures in place, and ensuring the crew is well-trained in their use, a vessel can maintain steerage and navigate safely even in the unlikely event of a telemotor system failure.

In the dire scenario of a total hydraulic system failure on a vessel, steering becomes extremely challenging but not impossible. Several emergency procedures and backup systems exist to regain some level of steerage and maneuverability, although they are generally less precise and require more effort from the crew.

Here’s how steering can be achieved in such a situation:

1. Emergency Steering Gear:

• Dedicated System: Many larger vessels, including superyachts, are equipped with a separate emergency steering gear system, independent of the main hydraulic system.
• Manual or Power-Assisted: This system might be manually operated using a hand pump and a dedicated tiller or be power-assisted using a different power source, such as an electric motor or a smaller, dedicated hydraulic pump.
• Reduced Capacity: While it might not offer the same responsiveness or full range of motion as the main steering gear, it’s designed to provide enough control to maneuver the vessel at a reduced speed to a safe location for repairs.

2. Jury-Rigged Systems:

• Rudder Tackle: In smaller vessels or as a last resort, a jury-rigged system using blocks, tackles, and lines can be set up to manually control the rudder.
• Chain and Shackle: Another option involves directly connecting a chain or strong rope to the rudder and manually hauling it to steer the vessel.
• Limitations: These jury-rigged systems are labor-intensive, offer limited control, and are generally suitable only for short distances or in calm weather conditions.

3. Differential Thrust (Twin-Screw Vessels):

• Varying Propeller Speeds: On vessels with twin propellers, steering can be partially achieved by varying the speed or direction of each propeller.
• Limited Effectiveness: This method provides limited maneuverability and is less effective at higher speeds or in strong currents or winds.

4. Other Maneuvering Aids:

• Bow/Stern Thrusters: If available, bow and stern thrusters can be used to assist in turning the vessel or maintaining its heading, especially at low speeds or in confined spaces.
• Anchors: Dropping an anchor can be used to slow down the vessel or assist in turning, although this should be done cautiously to avoid grounding or other hazards.

Key Considerations:

• Crew Training: It’s vital that the crew is well-trained in emergency steering procedures and the operation of any backup or jury-rigged systems.   1. Emergency Procedures: Steering failure is more common than we think – Safety4Sea safety4sea.com
• Communication: Clear communication between the bridge and the engine room or steering gear compartment is essential for coordinating the use of backup systems and maneuvering the vessel safely.   1. BRIDGE AND ENGINE ROOM INTERACTIONS IN AN EMERGENCY – Britannia P&I Club britanniapandi.com
• Sea Conditions: The effectiveness of emergency steering methods can be significantly affected by sea conditions. Calm weather and low speeds increase the chances of success.

Conclusion:

While losing complete hydraulic steering is a serious situation, vessels are equipped with backup systems and procedures to maintain some level of steerage in such emergencies. The key is to have well-trained crew members who can quickly assess the situation, implement the appropriate backup measures, and navigate the vessel safely to a place where repairs can be made.