Revision Notes Anchoring

Comprehensive Guide to Anchoring on a Merchant Vessel

Anchoring is a vital skill for maritime officers, ensuring the secure and effective mooring of a vessel to the seabed. This detailed guide covers all aspects of anchoring, including procedures, equipment, maintenance, and considerations for ship handling from the bridge. These notes are designed to help Officer of the Watch and Master Mariner candidates master the art of anchoring.

Introduction to Anchoring

Anchoring involves the precise and secure mooring of a vessel using an anchor. This process requires careful planning and execution to ensure the vessel remains safely in position. Key elements include the use of appropriate equipment, understanding environmental conditions, and maintaining clear communication between the bridge and the forecastle team.

Anchoring Equipment

  1. Anchor
    • Types: Stockless, Danforth, and CQR anchors.
    • Function: Holds the ship in place by embedding into the seabed.
  2. Anchor Chain/Cable
    • Components: Chain, shackles, and connectors.
    • Function: Connects the anchor to the vessel, absorbs shock loads.
  3. Windlass
    • Function: Mechanically raises and lowers the anchor.
    • Components: Gypsy wheel, capstan, and brake.
  4. Hawse Pipe
    • Function: Guides the anchor chain from the deck to the seabed.
    • Maintenance: Regular inspection for wear and corrosion.
  5. Chain Locker
    • Function: Stores the anchor chain when not in use.
    • Maintenance: Keep dry and free of rust, ensure proper drainage.

Anchoring Procedures

  1. Preparation
    • Check Equipment: Ensure the anchor, chain, and windlass are in optimal condition.
    • Communication: Establish clear communication between the bridge and forecastle.
    • Environmental Check: Assess wind, tide, and seabed conditions.
  2. Choosing the Anchoring Position
    • Depth and Holding Ground: Ensure suitable depth and seabed composition.
    • Swing Radius: Consider the vessel's swing radius to avoid collisions.
    • Proximity to Navigational Hazards: Ensure a safe distance from navigational hazards.
  3. Anchoring Maneuver
    • Slow Down: Gradually reduce the ship's speed as you approach the anchoring position.
    • Positioning: Head the vessel into the wind or current.
    • Letting Go: Release the anchor and let the chain run out under control.
  4. Securing the Anchor
    • Pay Out Chain: Let out enough chain (scope) – typically 5-7 times the depth of water.
    • Brake the Windlass: Apply the windlass brake to secure the anchor.
    • Check Holding: Ensure the anchor is holding by monitoring the vessel's movement.

Bridge Procedures and Ship Handling

  1. Communication
    • Internal Communication: Ensure clear and continuous communication between the bridge and forecastle team.
    • External Communication: Inform nearby vessels and port authorities if necessary.
  2. Position Monitoring
    • GPS and ECDIS: Use GPS and ECDIS to monitor the vessel's position and swing radius.
    • Visual Checks: Regularly check the vessel’s position using visual bearings on fixed points.
  3. Engine and Rudder Usage
    • Standby Engines: Keep engines on standby for maneuvering if needed.
    • Rudder Control: Use the rudder to assist in positioning the vessel during anchoring.

Maintenance of Anchoring Equipment

  1. Regular Inspections
    • Anchor Chain: Inspect for wear, rust, and deformation.
    • Windlass: Check for proper lubrication and operational integrity.
    • Hawse Pipes and Chain Lockers: Ensure cleanliness and free from obstructions.
  2. Operational Checks
    • Windlass Operation: Test the windlass under load conditions.
    • Brake Function: Ensure the windlass brake can hold the anchor chain securely.
  3. Cleaning and Lubrication
    • Chain and Windlass: Clean regularly to prevent rust and ensure smooth operation.
    • Lubricate: Apply grease to moving parts of the windlass and anchor chain.

Considerations for Anchoring

  1. Weather Conditions
    • Wind and Current: Anchor with the bow facing into the prevailing wind or current.
    • Weather Forecast: Monitor the weather forecast for changes that could affect anchoring.
  2. Tidal Information
    • Tidal Range: Be aware of the tidal range to avoid dragging during high or low tides.
    • Slack Water: Anchor at slack water when the current is minimal for easier positioning.
  3. Seabed Composition
    • Holding Ground: Choose anchoring spots with good holding ground, such as sand or mud.
    • Avoiding Obstacles: Ensure the seabed is free from debris, rocks, or other hazards.

Good Holding Ground

  • Sand: Provides excellent holding as the anchor can dig in deeply.
  • Mud: Also provides good holding, although not as strong as sand.
  • Clay: Offers very strong holding but can be difficult to break free.
  • Rock: Generally poor holding ground unless the anchor can secure itself in a crevice.

Navigation Equipment and Anchor Watch

Setting Up Navigation Equipment

  • GPS: Continuously monitor the vessel’s position to detect any dragging of the anchor.
  • ECDIS: Use ECDIS to visualize the anchor position and swing radius, setting alarms for any deviation outside the expected range.
  • Radar: Monitor surrounding traffic and ensure that the vessel remains within a safe distance from other vessels and navigational hazards.
  • AIS: Track nearby vessels and ensure clear communication if any vessel comes too close.

Officer of the Watch (OOW) Requirements for Anchor Watch

  • Regular Checks: Perform regular checks of the vessel's position, anchor chain tension, and surrounding environment.
  • Weather Monitoring: Continuously monitor weather conditions and be prepared to take action if adverse weather is forecasted.
  • Communication: Maintain communication with the bridge and other relevant personnel.
  • Record Keeping: Log all significant activities and observations in the ship's logbook.