CHIEF ENGINEER Unit 19 Bulkheads Q1

A transverse watertight bulkhead is a vertical wall or partition constructed across the width of a ship, dividing it into separate watertight compartments. These bulkheads are designed to prevent the spread of water in case of a hull breach or flooding, thereby enhancing the vessel’s safety and survivability.  

1. 3 Types Of Ship Bulkheads And How To Recognize Them – Plan M8

2. Bulkheads – Wärtsilä

Key Characteristics:

• Watertight: The primary function is to be impervious to water, even under significant pressure. This is achieved through robust construction, welded joints, and effective sealing around penetrations (pipes, cables, etc.).
• Transverse Orientation: They run athwartships (across the ship’s beam) from side to side, perpendicular to the centerline.   1. Bulkhead – Oxford Reference www.oxfordreference.com
• Compartmentalization: They divide the ship into multiple watertight compartments, limiting the impact of flooding to a single area and preventing the vessel from sinking rapidly.   1. Compartment (ship) – Wikipedia en.wikipedia.org
• Structural Strength: They also contribute to the ship’s structural strength, enhancing its resistance to bending and twisting forces.

Importance:

• Survivability: By containing flooding to a limited area, transverse watertight bulkheads significantly increase a ship’s chances of remaining afloat and stable even if its hull is breached. This allows for evacuation, repairs, or other emergency measures to be taken.
• Safety: They help prevent the rapid and catastrophic flooding that could lead to capsizing or sinking, protecting the lives of crew and passengers.
• Damage Control: In case of flooding, the bulkheads help isolate the affected compartment, making it easier to control and manage the situation.   1. 3 Types Of Ship Bulkheads And How To Recognize Them – Plan M8 planm8.io

Regulations and Standards:

• SOLAS: The International Convention for the Safety of Life at Sea (SOLAS) sets strict requirements for the number, location, and construction of watertight bulkheads on ships.   1. International Convention for the Safety of Life at Sea (SOLAS), 1974 www.imo.org
• Classification Societies: Classification societies also have rules and standards for watertight bulkheads, ensuring they meet the necessary strength and integrity requirements.   1. How transverse watertight bulkheads strengthening bulk carriers structural configuration ? bulkcarrierguide.com

Additional Points:

• Doors and Openings: Watertight bulkheads may have watertight doors or hatches to allow access between compartments, but these must be securely closed and sealed when not in use.   1. 3 Types Of Ship Bulkheads And How To Recognize Them – Plan M8 planm8.io
• Penetrations: Any penetrations through the bulkhead, such as for pipes or cables, must also be carefully sealed to maintain watertightness.
• Testing: Watertight bulkheads are subject to rigorous testing, including hose tests and hydrostatic pressure tests, to verify their integrity.

In conclusion, transverse watertight bulkheads are a crucial safety feature in ship design, serving to prevent the spread of flooding and enhance the vessel’s survivability in case of hull damage.

Transverse watertight bulkheads are an essential part of a vessel’s structure for several crucial reasons:

1. Flood Control and Survivability:

• Compartmentalization: The primary purpose of watertight bulkheads is to divide the ship into multiple watertight compartments. In the event of a hull breach or flooding, these bulkheads prevent water from spreading uncontrollably throughout the vessel, thus maintaining buoyancy and stability.
• Increased Survivability: By limiting flooding to a specific compartment, the ship’s chances of remaining afloat and stable are significantly improved, allowing time for crew and passengers to evacuate, or for repairs or salvage operations to be undertaken.

2. Structural Strength and Integrity:

• Transverse Stiffness: Transverse bulkheads act as structural members that reinforce the ship’s hull, increasing its resistance to bending and twisting forces caused by waves, loading, and other external factors.
• Longitudinal Strength: They also contribute to the ship’s longitudinal strength by acting as supports for the deck and other structural elements, particularly in areas with large openings or cargo holds.
• Collision Protection: In some cases, particularly near the bow, bulkheads are designed as collision bulkheads to absorb impact energy and limit damage in case of a collision.

3. Safety and Risk Mitigation:

• Reduced Risk of Capsizing: By containing flooding, bulkheads help prevent a rapid shift in the ship’s center of gravity, reducing the risk of capsizing or instability in damaged conditions.
• Improved Damage Control: Bulkheads enable the crew to isolate the flooded compartment and focus their efforts on damage control and dewatering, increasing the chances of saving the vessel.
• Enhanced Safety for Crew and Passengers: By providing a degree of compartmentalization and preventing rapid sinking, bulkheads increase the time available for evacuation and rescue, potentially saving lives.

4. Regulatory Compliance:

• SOLAS Requirements: The International Convention for the Safety of Life at Sea (SOLAS) mandates the installation of watertight bulkheads in specific locations and with specific construction standards to ensure the vessel’s safety and survivability.
• Classification Society Rules: Classification societies also have stringent requirements for watertight bulkheads, ensuring they meet the necessary strength and integrity standards for the ship’s class and intended service.

In conclusion, transverse watertight bulkheads are an indispensable component of a vessel’s structure, playing a crucial role in flood control, structural strength, and overall safety. By preventing the uncontrolled spread of water in case of damage, they significantly enhance the ship’s survivability and protect the lives of those onboard.

The positions of the most important watertight bulkheads on a vessel are primarily determined by safety considerations and regulatory requirements, with the goal of ensuring the ship’s survivability in case of flooding. The key bulkheads include:

1. Collision Bulkhead:

• Location: Located at a specified distance from the forward perpendicular (typically 5% of the ship’s length or 10 meters, whichever is less), as per SOLAS regulations.
• Purpose: Protects the ship from extensive flooding in case of a head-on collision, allowing it to remain afloat and stable.

2. Afterpeak Bulkhead:

• Location: Situated at the aft (rear) end of the ship, separating the afterpeak tank (used for ballast or storage) from the rest of the vessel.
• Purpose: Prevents flooding from the stern, which can significantly impact stability and steerage.

3. Machinery Space Bulkheads:

• Location: Surround the engine room and other machinery spaces, isolating them from the rest of the ship.
• Purpose: Contains flooding in case of damage or leaks within the machinery spaces, preventing it from spreading to other compartments and affecting the vessel’s stability.

4. Other Transverse Bulkheads:

• Location: Additional transverse bulkheads are placed throughout the ship’s length, dividing it into multiple watertight compartments. Their positions are determined based on the vessel’s design, size, and intended use, along with stability and subdivision calculations.   1. 3 Types Of Ship Bulkheads And How To Recognize Them – Plan M8 planm8.io
• Purpose: These bulkheads further enhance the ship’s survivability by limiting the extent of flooding in case of damage, allowing for better control and potential salvage.

5. Longitudinal Bulkheads (if applicable):

• Location: Some ships, especially tankers, may have longitudinal bulkheads running along the ship’s length, further subdividing cargo tanks or other compartments.   1. 3 Types Of Ship Bulkheads And How To Recognize Them – Plan M8 planm8.io
• Purpose: These bulkheads provide additional protection against flooding and improve the ship’s stability in case of damage to the side shell.

Key Points:

• SOLAS Regulations: The International Convention for the Safety of Life at Sea (SOLAS) sets specific requirements for the number, location, and construction standards of watertight bulkheads to ensure adequate subdivision and survivability.   1. International Convention for the Safety of Life at Sea (SOLAS), 1974 www.imo.org
• Classification Society Rules: Classification societies also have their own rules and standards for watertight bulkheads, which must be adhered to for the vessel to maintain its class.
• Floodable Length Calculations: The positioning of transverse bulkheads is often determined based on floodable length calculations, which assess the impact of flooding in different compartments on the ship’s stability and ability to remain afloat.   1. floodable length – Maat Hydro www.sistre-shipdesign-software.com

The precise location of these bulkheads can vary depending on the ship’s type, size, and design. However, their strategic placement throughout the vessel is crucial for ensuring its safety and survivability in case of flooding or damage, making them an integral part of the ship’s structural design.

The foremost continuous bulkhead, also known as the collision bulkhead, is of stronger construction than other transverse bulkheads primarily because of its crucial role in protecting the ship from the consequences of a head-on collision.

Here are the main reasons for its reinforced design:

1. Impact Resistance: The foremost bulkhead is the first line of defense in a collision scenario. It’s designed to withstand the impact forces from a head-on collision, preventing extensive damage and flooding in the forward part of the ship.
2. Watertight Integrity: It must maintain its watertight integrity even under severe impact, preventing water from flooding the forward compartments and compromising the ship’s buoyancy and stability.
3. Minimizing Floodable Length: The collision bulkhead limits the floodable length of the ship, which is the maximum length of the ship that can be flooded without causing it to sink. By containing flooding to the forwardmost compartment, the bulkhead helps ensure the vessel’s survival.
4. Regulatory Requirements: The International Convention for the Safety of Life at Sea (SOLAS) mandates specific construction standards for the collision bulkhead, including increased thickness, additional stiffening, and stricter welding requirements compared to other transverse bulkheads.
5. Enhanced Safety: A stronger collision bulkhead provides a greater margin of safety in case of a collision, potentially saving lives and preventing significant damage to the vessel and its cargo.

Specific Construction Features:

• Increased Thickness: The collision bulkhead is typically thicker than other transverse bulkheads to withstand greater impact forces.
• Additional Stiffening: It is reinforced with additional stiffeners and bracings to increase its strength and resistance to buckling.
• Higher Grade Steel: It may be constructed from higher-grade steel with improved yield and tensile strength compared to other bulkheads.
• Special Welding Requirements: The welds joining the bulkhead plates are subject to stricter quality control and inspection standards to ensure their integrity.
• No Penetrations: Ideally, the collision bulkhead should have minimal or no penetrations (pipes, cables, etc.) to minimize potential leakage points. If penetrations are unavoidable, they must be carefully designed and sealed to maintain watertightness.   1. 46 CFR § 179.310 – Collision bulkheads. – Law.Cornell.Edu www.law.cornell.edu

In summary, the foremost continuous bulkhead’s reinforced construction is vital for protecting the ship and its crew in the event of a collision. By withstanding impact forces, maintaining watertight integrity, and limiting floodable length, it significantly enhances the vessel’s survivability and safety at sea.