Section 14.2 Mooring Arrangements and Best Practices (Lines, Stoppers, Winches)

Mooring is the process of securing a vessel to a fixed or floating object, typically a quay, jetty, buoy, or another ship. For large bulk carriers, with their significant windage area (especially in ballast) and displacement, effective mooring is crucial for maintaining the vessel’s position during cargo operations, bunkering, or other port activities, and for ensuring the safety of the ship, crew, and shore facilities. A well-planned mooring arrangement, utilizing appropriate lines, stoppers, and winches, combined with diligent monitoring and tending, is essential to counteract the forces of wind, current, tide, and passing vessels. This section will cover the principles of mooring, common arrangements, the equipment involved, and best practices for safe and effective mooring operations.

1. Purpose and Principles of Mooring:

Primary Purpose: To hold the vessel securely in a desired position alongside a berth or other fixed/floating point, preventing unwanted movement (surge, sway, yaw) that could:

Interrupt cargo operations.

Damage loading/discharging equipment (e.g., shiploaders, conveyors, grabs).

Cause contact between the ship and the quay, fenders, or other vessels, leading to damage.

Put excessive strain on gangways or accommodation ladders.

Endanger personnel.

Counteracting Forces: A mooring arrangement must be designed to effectively counteract various external forces:

Wind: Can exert significant force on the vessel’s exposed hull and superstructure, pushing it onto or off the berth, or along it.

Current/Tidal Streams: Can exert lateral or longitudinal forces.

Waves and Swell: Can cause the vessel to surge, sway, and heave, putting dynamic loads on mooring lines. Even minor swell in seemingly sheltered berths can be problematic for large ships.

Passing Vessels: The hydrodynamic forces (suction and pressure waves) generated by passing vessels can cause the moored ship to move significantly if lines are not properly tended.

Changes in Draft and Trim: During cargo operations, as the vessel’s draft and trim change, the tension and geometry of mooring lines will alter, requiring adjustment.

Elasticity and Strength:

Mooring lines need a degree of elasticity to absorb shock loads from dynamic forces without parting.

The overall strength of the mooring system (lines, winches, bitts, fairleads) must be adequate for the expected forces.

2. Mooring Lines – Types, Characteristics, and Care:

Mooring lines are the primary means of securing the vessel. They can be made of natural fibers (rare now for large ships), synthetic fibers, or steel wire.

A. Types of Mooring Lines:

Steel Wire Ropes:

Advantages: High strength-to-diameter ratio, good abrasion resistance, less susceptible to stretch under steady load (though less elastic for shock loads).

Disadvantages: Heavy to handle, prone to kinking and corrosion if not maintained, low elasticity (can part suddenly under shock loads if not used with a synthetic tail), can cause severe injuries if they part under tension (“snap-back”).

Construction: Typically 6-strand wire rope (e.g., 6×24, 6×36, 6×41) with a fiber or steel core.

Use: Often used for permanent moorings or in situations requiring very high strength, sometimes as breast lines or springs on large vessels. Often fitted with synthetic tails to provide elasticity.

Synthetic Fiber Ropes: Most common on modern vessels due to their favorable strength-to-weight ratio, ease of handling, and inherent elasticity.

Polypropylene (PP): Lightweight, floats, relatively inexpensive. Lower strength and abrasion resistance compared to other synthetics. Can degrade with UV exposure. Often used for heaving lines or lighter duties.

Polyester (e.g., Terylene, Dacron): Good strength, good abrasion and UV resistance, relatively low stretch (but more than wire). Sinks in water.

Nylon (Polyamide – PA): Very high strength and excellent elasticity (stretches significantly under load, absorbing shock). However, loses some strength when wet and has a higher “snap-back” potential if it parts. Sinks in water.

High Modulus Synthetic Fibers (HMSF):

HMPE (High Modulus Polyethylene – e.g., Dyneema®, Spectra®): Extremely high strength-to-weight ratio (stronger than steel wire of same weight), very low stretch, floats, good abrasion and UV resistance. Expensive. Requires careful handling on winches and bitts due to its slipperiness and low friction.

Aramid (e.g., Kevlar®, Twaron®): Very high strength, low stretch, good heat resistance. Susceptible to UV degradation and internal abrasion if not properly protected. Expensive.

LCP (Liquid Crystal Polymer – e.g., Vectran®): High strength, very low stretch, good abrasion resistance.

Composite/Blended Ropes: Combining different fibers to achieve specific properties (e.g., a polyester jacket over a nylon core).

B. Mooring Line Terminology and Layout: A typical mooring arrangement uses lines with specific functions based on their orientation:

Head Lines: Run forward from the bow to the quay. Primarily prevent the vessel from moving astern and help keep the bow in.

Stern Lines: Run aft from the stern to the quay. Primarily prevent the vessel from moving ahead and help keep the stern in.

Breast Lines (Fore and Aft): Run nearly perpendicular from the ship’s side (bow and quarter) to the quay. Primarily prevent the vessel from moving sideways off the berth.

Spring Lines: Run diagonally forward or aft from the ship to the quay.

Forward Springs (run aft from the forward part of the ship): Prevent the vessel from surging forward.

Back Springs / Aft Springs (run forward from the after part of the ship): Prevent the vessel from surging astern. Spring lines are crucial for controlling longitudinal movement.

Optimal Angle: Mooring lines are most effective when their horizontal angle to the quay is relatively small (long leads are better than short, steep leads for horizontal restraint, though very long leads reduce transverse holding). Vertical angles also affect efficiency.

C. Care and Maintenance of Mooring Lines:

Regular Inspection: Check for wear, abrasion (chafing), broken strands/yarns, cuts, kinks (in wire ropes), heat damage, chemical damage, or UV degradation.

Protection from Chafing: Use chafing guards (canvas, leather, specialized protectors) where lines pass through fairleads or over sharp edges.

Proper Stowage: Keep lines clean and stowed away from direct sunlight, chemicals, and heat sources when not in use. Synthetic ropes should be stowed on reels or coiled neatly to prevent kinking. Wire ropes should be spooled correctly on winch drums and lubricated.

Avoid Overloading: Do not exceed the Safe Working Load (SWL) of the lines. SWL is typically a fraction (e.g., 1/5th to 1/6th) of the Minimum Breaking Load (MBL).

Avoid Sharp Bends: Leads lines with fair curves to avoid stress concentrations.

Splicing and End Terminations: Must be done correctly by competent personnel. Eye splices are common.

Rotation and End-for-Ending: To distribute wear, lines can be periodically rotated in their use or “end-for-ended.”

Retirement Criteria: Lines must be discarded when they show excessive wear, damage, or have reached the end of their recommended service life as per company policy or manufacturer’s guidance. Records of line inspections and retirement are important.

3. Mooring Winches and Stoppers:

A. Mooring Winches (Covered in Chapter 2, Section 1):

Function: Used to heave in mooring lines, hold them under tension, and pay them out.

Brake Capacity: The winch brake is critical for holding the line. Its holding capacity should be matched to the strength of the mooring line (typically set to render at around 60-80% of the line’s MBL, but always follow manufacturer/company guidance). Brakes must be regularly inspected, maintained, and tested.

Warping Drum: Used for heaving on lines. Proper technique (sufficient turns, avoiding riding turns) is essential.

Storage Drum (if fitted): For stowing the line. Ensure lines are spooled evenly.

B. Mooring Line Stoppers:

Purpose: Used to temporarily hold the tension on a mooring line while it is being transferred from the winch warping drum to mooring bitts, or to secure a line that is not on a winch drum.

Types:

Rope Stoppers (for fiber ropes): Made of natural or synthetic rope, often plaited or with a toggle. They are passed around the mooring line and secured to a strong point (e.g., bitt, pad-eye). The friction holds the line. Common types include “West Country Stopper” or “Single Stopper.”

Chain Stoppers (for wire ropes, or sometimes for very large fiber ropes): A short length of chain with a slip hook or pelican hook that engages a link or special fitting on the wire.

Mechanical/Patented Stoppers: Various proprietary designs.

Safe Use: Stoppers must be strong enough for the line they are holding. They should be applied correctly to avoid damaging the mooring line. Personnel must be trained in their safe application and release. The line between the stopper and the winch should be slacked before the stopper takes the full load.

4. Mooring Bitts, Fairleads, and Rollers:

Mooring Bitts (Bollards on Ship): Strong, paired vertical posts on deck used for making mooring lines fast. Lines are turned around the bitts in figure-eight fashion.

Fairleads (Chocks): Openings or fittings in the ship’s bulwark or deck edge through which mooring lines pass to guide them to winches or bitts and to change their direction with minimal friction and chafing.

Types: Open fairleads, closed fairleads (with rollers), panama chocks (for canal transits).

Rollers (Pedestal Rollers, Multi-Angle Fairleads): Used to guide lines and reduce friction, especially where lines change direction significantly. Must be kept well-greased and free to rotate.

5. Planning the Mooring Arrangement:

Before arrival, a preliminary mooring plan should be developed, considering:

Berth Characteristics: Length of quay, position of shore bollards, fendering arrangements, water depth, potential for surge or passing vessel effects. This information is often in port guides or obtained from the agent.

Vessel Size and Freeboard: Influences the lead and length of lines.

Expected Weather Conditions: Strong onshore/offshore winds or cross-currents will require a more robust arrangement with more lines or specific leads.

Tidal Range: Significant tidal ranges will necessitate frequent tending of lines.

Cargo Operations: The mooring arrangement should not obstruct cargo handling equipment (cranes, loaders) and should allow for changes in draft and freeboard as cargo is worked.

Number and Type of Lines Available: Use the strongest lines for the most critical positions (e.g., springs, breast lines in exposed conditions).

Balanced Arrangement: Aim for a balanced distribution of lines forward and aft, with appropriate leads to counter all expected forces. Avoid having all lines taking strain in one direction only.

Shared Loads: Try to arrange lines so that multiple lines share the load from a particular direction.

Communication with Pilot and Mooring Gangs: Discuss the intended mooring plan with the pilot before berthing. Coordinate with shore mooring gangs for handling lines ashore.

6. Best Practices for Mooring Operations:

A. Safety First (Paramount):

Risk Assessment: Mooring operations are inherently hazardous due to lines under high tension. Conduct a thorough risk assessment and pre-mooring safety briefing (toolbox talk).

PPE: All personnel involved must wear appropriate PPE (hard hats, safety shoes, gloves, high-visibility vests).

Snap-Back Zones: Identify and mark “snap-back zones” – the areas where a line might recoil violently if it parts. Personnel must never stand in these zones. This is especially critical for synthetic ropes with high stretch (like nylon) and for wire ropes.

Clear Decks: Keep mooring decks clear of obstructions and tripping hazards.

Controlled Heaving/Lowering: Heave or pay out lines slowly and under control. Avoid sudden shock loads.

Communication: Clear and concise communication between the bridge, mooring stations (fore and aft), and shore mooring gangs using hand signals, VHF radio, or sound-powered telephones.

Winch Operation: Only trained personnel should operate winches. Never leave a winch unattended when it is under load or heaving. Ensure winch drums are not overfilled.

Handling Lines: Handle lines carefully to avoid hand injuries. Never stand in a bight of rope.

Stoppers: Apply and release stoppers correctly and safely.

Fatigue Management: Mooring can be a prolonged operation. Ensure crew are adequately rested.

B. Execution of Mooring:

Lines Sent Ashore: Send lines ashore in the agreed order (often springs first, then breast lines, then head/stern lines, but this varies). Use heaving lines to pass messenger lines, then the mooring lines.

Winch Use: Heave lines taut using winch warping drums.

Making Fast on Bitts: Once a line is brought to the desired tension, transfer it to bitts using a stopper. Ensure sufficient turns are taken on the bitts (typically figure-eights) to hold the line securely.

Equalizing Tension: As much as possible, try to equalize the tension on lines that are working together (e.g., multiple head lines). This can be judged by the “feel” of the line or by using tension meters if available (rare on most bulkers for all lines).

Fenders: Ensure vessel’s fenders (if used) and quay fenders are correctly positioned to prevent hull contact.

C. Tending Moorings:

Continuous Monitoring: Once moored, lines must be continuously monitored for tension.

Adjust for Tide and Draft Changes: As the tide rises/falls or as the ship’s draft changes during cargo operations, mooring lines will slacken or tighten. They must be tended (adjusted) regularly to maintain appropriate tension and keep the vessel securely alongside. This is an ongoing task for the deck watch.

Adjust for Weather Changes: If wind or current conditions change, lines may need to be slacked or tightened, or additional lines run out.

Passing Vessels: Be particularly vigilant when other vessels are passing close by, as their wash can put sudden, heavy strains on mooring lines. Have crew ready to tend lines.

D. Use of Tugs:

Tugs are often essential for berthing and unberthing large bulk carriers. Their effective use is coordinated by the pilot and Master. (Covered more in berthing section).

E. Letting Go Moorings (Unmooring):

Plan the sequence of letting go lines (often in reverse order of mooring, or as advised by pilot/port).

Ensure tugs are fast (if used) before letting go all lines.

Handle lines carefully as they come aboard to prevent snagging or injury.

Stow lines properly after use.

7. Master’s Responsibilities:

Overall Safety of Mooring Operations: Ensure all procedures are followed, risks are assessed, and safety precautions are paramount.

Approval of Mooring Plan: Review and approve the mooring arrangement proposed by the Chief Officer.

Supervision: Oversee the mooring/unmooring operations from the bridge, coordinating with the pilot, mooring stations, and engine room.

Ensuring Competency: Confirm that officers and crew involved are competent in line handling, winch operation, and safety procedures.

Decision Making: Make critical decisions regarding the number of lines, adjustments needed, or if conditions become unsafe to remain alongside.

Communication: Ensure effective communication with all parties.

Safe and effective mooring of a bulk carrier is a team effort requiring skill, vigilance, and strict adherence to safety procedures. It ensures the vessel remains secure during its crucial interface with the shore for cargo operations, protecting the ship, its crew, and the port environment. The Master’s leadership in planning, supervision, and upholding safety standards is paramount.