Section 1.3 Hatch Covers: Types, Operation, Maintenance, and Weathertightness

Hatch covers on bulk carriers are much more than simple lids; they are critical structural components and the primary barrier protecting valuable cargo from the elements and ensuring the vessel’s seaworthiness. Their proper operation, diligent maintenance, and guaranteed weathertightness are paramount responsibilities for the Master and crew. Given the enormous size of hatch openings on bulk carriers (to facilitate rapid loading and discharge), the integrity of the hatch covers is directly linked to the safety of the vessel.

1. Types of Hatch Covers:

While various designs exist, the most common types found on bulk carriers are steel, mechanically operated covers.

1. Folding Hatch Covers (e.g., MacGregor-type):
   1. Description: These consist of multiple panels (typically two to four per hatch) hinged together. One panel is often equipped with wheels that run on a track along the hatch coaming. Hydraulic or electric mechanisms are used to lift and fold the panels, usually towards one or both ends of the hatch, stacking them vertically.
   2. Operation: Hydraulic cylinders typically act on bell cranks or linkages to raise the leading panel, which then pulls the subsequent panels into a folded stack.
   3. Advantages: Relatively quick operation, can be designed for large hatch openings, and when open, provide a largely unobstructed area for cargo operations.
   4. Common On: Widely used on Handysize, Supramax, Panamax, and even some Capesize bulkers.
2. Side-Rolling Hatch Covers (e.g., “Piggy-back” or single panel rolling):
   1. Description: These covers typically consist of one or two large panels per hatch that roll transversely (to the sides of the vessel) onto stowage ramps or areas on the deck. “Piggy-back” systems involve one panel rolling underneath another before both are moved to the stowed position.
   2. Operation: Usually operated by electric or hydraulic motors driving a rack-and-pinion system or chain drives, with the panels moving on wheels along transverse tracks.
   3. Advantages: Can cover very wide hatch openings, provide a completely clear opening when stowed, and are robust.
   4. Common On: Often found on larger bulk carriers like Panamax and Capesize vessels, especially those with wide beams and large hatches (e.g., OBO carriers in the past, or very large ore carriers).
3. End-Rolling Hatch Covers:
   1. Description: Similar to side-rolling but the panels roll longitudinally towards the ends of the hatch. Less common on typical bulk carriers than folding or side-rolling types.
4. Stacking Hatch Covers:
   1. Description: Multiple individual panels are lifted by a crane (either ship’s gear or shore crane) and stacked one on top of the other, or on a designated area on deck.
   2. Operation: Slower, crane-dependent.
   3. Advantages: Simpler design, fewer moving parts.
   4. Common On: More common on smaller vessels, barges, or specialized carriers, less so on modern, large bulk carriers due to operational speed requirements.
5. Pontoon Hatch Covers:
   1. Description: Large, single-piece covers that are lifted on and off the hatch coaming by shore cranes or, occasionally, very heavy-duty ship’s cranes.
   2. Operation: Entirely crane-dependent.
   3. Advantages: Simple, robust, good sealing.
   4. Common On: Some older vessels or specific trades. Not typical for modern high-throughput bulk carriers.

2. Operation of Hatch Covers:

Safe and efficient operation requires adherence to procedures and awareness of potential hazards.

1. Pre-Operation Checks:
   1. Ensure no personnel are in the path of moving panels or on top of the covers.
   2. Verify no obstructions on tracks, coamings, or sealing surfaces.
   3. Check hydraulic oil levels and pressures (for hydraulic systems).
   4. Ensure power is available (for electric systems).
   5. Confirm all securing devices (cleats, wedges) are released.
2. During Operation:
   1. Operate controls smoothly and avoid jerky movements.
   2. Monitor the movement of panels for any signs of binding, misalignment, or unusual noises.
   3. If multiple persons are involved, ensure clear communication and one designated operator.
   4. In windy conditions, exercise extreme caution as panels can act like sails.
3. Post-Operation (Closing):
   1. Ensure panels are correctly landed and aligned on the coaming.
   2. Engage all securing cleats, wedges, and cross-joint seals/wedges as per design. This is critical for weathertightness and structural integrity.
   3. Confirm all tell-tales or indicators show correct closure and securing.

Analysis for the Master (Operation): The Master must ensure that crew members operating hatch covers are properly trained and familiar with the specific system on board. Standard Operating Procedures (SOPs) should be in place and strictly followed. Incidents involving hatch covers (personnel injury or equipment damage) can have severe consequences. The speed of operation is often a commercial pressure, but safety must never be compromised.

3. Maintenance of Hatch Covers:

Diligent maintenance is the key to reliable operation and long-term weathertightness. Neglected hatch covers are a primary cause of cargo damage claims and can even threaten the vessel’s safety.

1. Routine Inspections (by crew):
   1. Seals (Rubber Gaskets): Check for elasticity, permanent deformation (compression set), cracks, cuts, missing sections, and paint/cargo residue contamination.
   2. Compression Bars (Landing Surfaces on Coaming): Inspect for straightness, corrosion, pitting, and damage. A smooth, even surface is essential for proper seal compression.
   3. Tracks and Wheels: Clean tracks of debris and cargo. Check wheels for wear, damage, and free rotation. Lubricate as required.
   4. Hydraulic Systems: Inspect hoses for leaks, chafe, or deterioration. Check hydraulic rams for leaks and corrosion on piston rods. Monitor oil levels and condition.
   5. Electric Systems: Check motors, wiring, limit switches, and control boxes for damage or corrosion.
   6. Moving Parts (Hinges, Pins, Rollers): Lubricate regularly. Check for wear, seizure, or damage.
   7. Securing Devices (Cleats, Wedges, Dogs): Ensure they are all present, functional, and can be properly tightened. Check for corrosion or deformation.
   8. Drainage Channels and Non-Return Valves (Drain Valves): Coamings are fitted with drainage channels to carry away water that gets past the initial seals. These channels must be clear, and their non-return drain valves (to prevent water from sloshing back up from the deck) must be functional. This is a critically important but often overlooked area.
   9. Steel Structure (Panels and Coamings): Inspect for corrosion, cracks, and deformation (especially from grab damage or heavy loads).
2. Planned Maintenance (as per PMS):
   1. Regular lubrication schedules.
   2. Hydraulic oil sampling and replacement.
   3. Greasing of wheel bearings.
   4. Adjustment of cleats and wedges.
   5. Minor steel repairs (e.g., straightening bent sections, repairing small cracks).
   6. Touch-up painting to prevent corrosion.

Analysis for the Master (Maintenance): The Master must champion a proactive maintenance culture. Relying solely on pre-loading surveys to find defects is reactive and costly. A robust PMS, diligently followed by the crew (especially the Chief Officer and Bosun), is essential. Adequate spare parts (seals, hydraulic hoses, cleats, etc.) should be maintained onboard. The Master should personally conduct periodic inspections of hatch cover condition and maintenance records.

4. Weathertightness:

This is the ultimate test of hatch cover integrity. Failure to maintain weathertightness can lead to:

1. Cargo damage from seawater or rain (leading to commercial claims).
2. Water ingress affecting vessel stability.
3. Corrosion of hold structures.
4. Achieving Weathertightness:
   1. Proper Sealing Arrangement: Relies on the compression of a rubber gasket (on the panel) against a flat steel compression bar (on the coaming). The design aims for a “line contact” or a specific compression footprint.
   2. Correct Securing: All cleats and wedges must be fully and evenly tightened to achieve the designed compression on the seal. Cross-joint wedges between panels are equally important.
   3. Structural Integrity: Deformed panels or coamings will prevent proper sealing, no matter how good the rubber gasket.
5. Testing for Weathertightness:
   1. Hose Test (IMO MSC/Circ.1071): Water from a hose (specific pressure and distance) is directed at the joints and perimeter of the hatch covers. Any leakage into the hold indicates a lack of weathertightness. This is the most common method but has limitations (e.g., cannot pinpoint exact leak location easily, can be subjective).
   2. Ultrasonic Test (UST): This is the preferred and most accurate method. An ultrasonic transmitter is placed inside the empty hold, and a receiver is passed along the outside of the hatch cover joints and perimeter. The receiver detects any ultrasonic sound escaping through gaps, providing a precise location and an indication of the severity of the leak (often as a decibel reading). This test can be done quickly, irrespective of weather, and provides quantifiable results. It is increasingly required by P&I clubs and charterers.
   3. Chalk Test: A traditional method where chalk is applied to the compression bar. After closing and reopening the hatch, the transfer (or lack thereof) of chalk to the rubber seal indicates the extent and evenness of compression. Useful for checking seal contact but doesn’t confirm weathertightness directly.
   4. Light Test (in darkness): Shining a powerful light from inside the hold towards the closed hatch covers (in a darkened hold) can sometimes reveal light leakage, but this is the least reliable method.

Analysis for the Master (Weathertightness): The Master is responsible for ensuring the vessel’s hatches are weathertight before proceeding to sea or encountering expected foul weather.

1. Regular Testing: Weathertightness testing (preferably ultrasonic) should be conducted regularly, especially after any repairs, before loading sensitive cargoes, or if there’s any doubt.
2. Record Keeping: All tests, maintenance, and repairs to hatch covers should be meticulously recorded.
3. Training: Crew should be trained in proper securing techniques and be able to identify potential weathertightness issues.
4. Commercial Implications: Failed weathertightness tests can lead to off-hire, delays, and costs for rectification. P&I Clubs often scrutinize hatch cover maintenance records heavily in cargo damage claims.

Hatch covers are a system requiring constant vigilance. Their robust design must be matched by equally robust operational and maintenance practices, under the diligent oversight of the Master, to ensure they fulfill their critical role in protecting the cargo and the ship itself.