Aux 2 Unit 15 Q2

The collision bulkhead is a crucial safety feature in a ship’s design. Its primary purpose is to prevent extensive flooding in the forward part of the vessel in case of a head-on collision. This bulkhead acts as a barrier, limiting the inflow of water and helping the ship remain afloat and stable even with damage to the bow.  

Here’s a more detailed breakdown of its purpose:

• Damage Limitation: In a collision, the collision bulkhead absorbs the impact and prevents water from flooding the forward compartments, such as the forepeak tank or cargo holds. This limits the extent of damage and helps maintain the ship’s buoyancy and stability.  
• Maintaining Seaworthiness: By preventing excessive flooding, the collision bulkhead allows the ship to remain seaworthy, even with damage to the bow. This enables the crew to take necessary actions, such as making temporary repairs, deploying pumps, or even continuing the voyage if the damage is not severe.  
• Protecting Vital Spaces: The collision bulkhead also protects vital spaces like the engine room and accommodation areas from flooding, ensuring the continued operation of essential systems and the safety of the crew and passengers.  
• Enhancing Survivability: The collision bulkhead contributes significantly to the ship’s overall survivability in case of a collision. It provides a critical safety margin, allowing time for evacuation, rescue operations, or salvage efforts if necessary.  

Key Characteristics of a Collision Bulkhead:

• Location: It’s located at a specific distance from the forward perpendicular (typically 5% of the ship’s length or 10 meters, whichever is less), as mandated by the International Convention for the Safety of Life at Sea (SOLAS).  
• Strength: It’s designed to be stronger than other transverse bulkheads to withstand the impact forces of a collision.
• Watertightness: It must be completely watertight to prevent any leakage into the forward compartments.  
• Construction: It typically has increased thickness, additional stiffening, and stricter welding requirements compared to other bulkheads.  

In essence, the collision bulkhead is a vital safety feature that acts as a “second line of defense” after the ship’s bow. By limiting flooding and maintaining the vessel’s integrity in the event of a collision, it significantly enhances safety at sea and protects human life.  

The collision bulkhead is subject to stringent regulations regarding its dimensions and positioning to ensure it effectively protects the vessel in the event of a collision. These regulations are primarily outlined in SOLAS Chapter II-1, Part B-2, Regulation 11 “Collision bulkhead and decks.”  

Here are the key requirements:

1. Position:

• Forward of the Forward Perpendicular (FP): The collision bulkhead must be located not less than 5% of the ship’s length abaft (behind) the forward perpendicular (FP). The FP is a vertical line drawn at the intersection of the forward end of the load waterline and the designed waterline.
• Alternative Distance: Alternatively, it can be located not less than 10 meters (32.8 feet) plus 3% of the ship’s length abaft the FP.
• Smaller Distance: In ships with a length less than 50 meters (164 feet), the distance can be reduced to 5 meters (16.4 feet) abaft the FP.

2. Construction:

• Strength: It must be of substantial construction and be capable of withstanding, with a safety margin, the maximum head of water that it might have to sustain in the event of damage to the ship.
• Stiffeners: It should be stiffened in accordance with the classification society’s rules to ensure adequate strength and prevent buckling under pressure.
• Watertightness: It must be effectively watertight up to the freeboard deck.

3. Openings:

• No Doors or Openings: Ideally, the collision bulkhead should have no doors or openings.
• Exceptions: If openings are unavoidable for access or operational purposes, they must be fitted with watertight closures that comply with the requirements of SOLAS.

4. Extent:

• Up to the Freeboard Deck: The collision bulkhead should extend up to the freeboard deck, which is the uppermost complete deck exposed to weather and sea.  
• Higher Extension: In some cases, it may be required to extend to a higher deck, especially in ships with a long forward superstructure.

5. Additional Requirements:

• Steps and recesses: Steps or recesses in the collision bulkhead should be kept to a minimum and comply with specific construction requirements to maintain its strength and watertightness.
• Pipes and Cables: Any pipes or cables passing through the collision bulkhead must be fitted with suitable glands or other arrangements to ensure watertightness.

Purpose of these Regulations:

• Survivability: The regulations aim to ensure that the collision bulkhead can effectively limit flooding in the forward part of the ship in case of a collision, enhancing the vessel’s survivability.
• Stability: By preventing excessive flooding, the bulkhead helps maintain the ship’s stability and prevents it from capsizing.
• Safety: It protects vital spaces like the engine room and accommodation areas from flooding, ensuring the safety of the crew and passengers.  

Conclusion:

The regulations regarding the collision bulkhead’s dimensions and position are crucial for ensuring the safety of ships and their occupants. By adhering to these requirements, shipbuilders and designers can create vessels that are more resilient to damage and have a higher chance of survival in the event of a collision.

A, B, and C class bulkheads are all types of fire-resistant divisions used on ships, but they differ in their construction and ability to withstand fire and smoke. These classifications are defined in SOLAS (Safety of Life at Sea) regulations to ensure adequate fire protection on board.  

Class A Bulkheads:

• Highest Fire Resistance: These offer the highest level of fire resistance.  
• Construction: Made of steel or equivalent material, suitably stiffened and insulated with approved non-combustible materials.  
• Fire Test: Must prevent the passage of smoke and flame to the end of a one-hour standard fire test.  
• Temperature Rise Limits: The average temperature on the unexposed side should not rise more than 140°C above the original temperature, and no single point should rise more than 180°C above the original temperature.
• Purpose: Used to create main vertical zones in a ship, dividing it into sections to contain fire and limit its spread.  

Class B Bulkheads:

• Moderate Fire Resistance: Offer a moderate level of fire resistance.
• Construction: Made of approved non-combustible materials. Combustible veneers may be permitted if they meet specific requirements.  
• Fire Test: Must prevent the passage of flame to the end of the first half-hour of the standard fire test.  
• Temperature Rise Limits: Similar to Class A, but with higher limits (average temperature rise not to exceed 140°C, and no single point exceeding 225°C).
• Purpose: Used for subdividing sections within main vertical zones, creating smaller fire-resistant compartments.

Class C Bulkheads:

• Lowest Fire Resistance: Provide the lowest level of fire resistance among the three.
• Construction: Constructed of approved non-combustible materials.  
• Fire Test: No specific requirements for preventing smoke or flame passage.
• Temperature Rise Limits: No limitations on temperature rise.
• Purpose: Primarily used for separating accommodation spaces or creating minor divisions within a fire zone. They slow down the spread of fire but don’t offer the same level of protection as Class A or B.

Key Differences Summarized:

Feature	Class A	Class B	Class C
Fire Resistance	Highest	Moderate	Lowest
Construction	Steel, insulated	Non-combustible	Non-combustible
Fire Test	1-hour	30-minute	None
Temperature Limits	Strictest	Moderate	None

In Conclusion:

The classification of bulkheads (A, B, and C) reflects their ability to withstand fire and smoke, providing a layered approach to fire protection on ships.

By using a combination of these bulkheads, along with other fire safety measures, vessels can effectively contain fires, protect vital spaces, and enhance the safety of crew and passengers.