A Guide to Normal vs. Non-Follow-Up (NFU) Steering and Steering Gear Operation Types
Steering is one of the most critical aspects of ship navigation, ensuring the vessel stays on course and maneuvers safely. Among the various steering gear operation modes, Normal (Follow Up) and Non-Follow-Up (NFU) modes play pivotal roles in different scenarios. Understanding their differences and when to use NFU steering is essential for safe and efficient ship handling.
This blog will explore the key differences between Normal and NFU steering, explain when NFU should be used, and provide an overview of various steering gear operation modes. Whether you’re a maritime professional or a marine engineering enthusiast, this guide will deepen your understanding of modern steering systems aboard ships.
What Are Normal (Follow-Up) and Non-Follow-Up (NFU) Steering Modes?
Follow-Up Mode (Normal Steering)
Follow-Up mode, often considered the principal mode of steering, uses a steering wheel where the rudder follows the inputs provided by the wheel. Here’s how it works:
- If the steering wheel is turned 10° to starboard (Stbd), the rudder moves to precisely 10° to Stbd and remains in that position as long as the wheel stays turned.
- To return the rudder to the midship (neutral) position, the wheel must be brought back to the midship position manually.
This mode is common in:
- Hand steering mode: The rudder angle corresponds to the wheel’s position, giving the helmsman precise control.
- Auto-steering mode: The wheel’s position or computerized system generates automatic course corrections based on the difference between the ordered course and the ship’s actual course.
Non-Follow-Up Mode (NFU Steering)
Non-Follow-Up mode is a backup or emergency steering mode where a lever controls the rudder movement. Unlike Normal steering, the NFU mode:
- Does not use a steering wheel but relies on an NFU lever.
- The NFU lever has no markings, and the rudder moves continuously as long as the lever is pressed to one side.
- The rudder stops moving the moment the lever is released.
- To return the rudder to midship, the lever must be pressed toward the opposite side until the rudder reaches the neutral position.
NFU mode serves as an essential backup when there’s a failure in the ship’s telemotor system or other primary steering mechanisms, as it sends rudder commands directly to the control unit.
Key Differences Between Normal and NFU Steering
| Feature | Normal (Follow-Up) Steering | Non-Follow-Up (NFU) Steering |
|---|---|---|
| Control Input | Steering wheel | NFU lever (no markings) |
| Movement Feedback | Rudder follows steering wheel input | Rudder moves continuously; stops when lever is released |
| Ease of Use | Intuitive, precise manual inputs | Requires consistent monitoring and manual adjustments |
| When Used | Standard operation and auto-steering | Emergency or backup steering; system failures |
When to Use NFU Steering?
NFU steering isn’t typically used during normal navigation but becomes invaluable in specific scenarios, such as:
1. Telemotor System Failures
When the steering system’s telemotor (responsible for transmitting movements from the helm to the rudder actuator) fails, NFU mode provides a direct connection to the control unit, ensuring the ship can still be steered.
2. Emergency Situations
NFU steering is particularly useful during emergencies, such as rudder or control gear failures. The manual nature of NFU offers reliable control when automated systems are compromised.
3. Maintenance and Testing
During maintenance procedures or testing of the steering system, NFU mode can be employed to manually move the rudder and ensure the system responds correctly.
Overview of Steering Gear Operation Modes
Modern vessels are equipped with various steering methods to handle a range of navigation needs. Here’s a quick look at the primary steering gear operation types:
1. Auto Steering Mode
- How it Works: The system automatically generates course corrections by comparing the ordered course with the actual course.
- When to Use: Ideal for open-sea navigation where minimal manual input is required.
2. Hand Steering Mode
- How it Works: The helmsman manually controls the wheel, adjusting the rudder angle to maintain or change course.
- When to Use: Common during port maneuvers, congested waterways, and situations requiring frequent course corrections.
3. Non-Follow-Up (NFU) Mode
- How it Works: A lever is used to move the rudder continuously in one direction until released. Operates independently of the telemotor system.
- When to Use: Used as a backup or emergency mode during steering system failures.
4. Local Steering Mode
- How it Works: Enables the steering gear to be directly controlled from the steering gear room instead of the bridge.
- When to Use: Used in emergencies, during maintenance, or when remote controls from the bridge are unavailable.
Practical Tips for Using NFU Mode
Using NFU mode requires focused attention and a solid understanding of its functionality. Here are some practical tips for maritime professionals operating NFU steering:
- Always keep a close eye on the rudder angle indicator to monitor rudder movements during NFU steering.
- Understand the ship’s response time to rudder movements. Larger vessels may take longer to react, requiring calculated adjustments.
- Coordinate closely with team members in critical situations, especially when steering under NFU mode requires continuous inputs.
- Practice NFU steering during drills to ensure you’re familiar with the controls and procedure in case of emergencies.
Why Understanding Steering Gear Modes Matters
The ability to switch seamlessly between steering modes isn’t just about convenience; it’s about safety. Knowing when and how to activate NFU mode, for example, can mean the difference between maintaining full control of the ship in an emergency or risking severe navigational errors.
Maritime professionals should be well-versed in operating all steering gear modes, understanding their applications and limitations to ensure smooth and efficient operations.
Elevating Your Maritime Expertise
Steering systems are the backbone of safe ship navigation, and understanding their intricacies can significantly enhance your skills as a maritime professional. By mastering the differences between Normal and NFU steering, alongside other operation modes, you position yourself to respond effectively during routine navigation and unforeseen emergencies.
Got questions about steering systems or looking to deepen your maritime knowledge? Get in touch with maritime training experts or explore resources tailored for professionals seeking to excel in the maritime industry.