Questions and Answers
What is 'Camber' in the context of ship construction?
What is one primary purpose of camber in ship decks?
Drainage
What does Tumblehome refer to?
Inward slope or curvature of a ship's hull
How does flare in ships benefit buoyancy and stability?
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The height of the ship at the midship section from the base line to the moulded line of the deck at side is referred to as the ______.
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What is the definition of Length Over All (L.O.A.)?
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Tumblehome was a common feature in modern ships.
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What does the term 'draft' refer to in ship construction?
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What is freeboard in ship terminology?
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What is the purpose of the hull structure in a ship?
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Which type of hull design provides extra protection against hull puncture and reduces the risk of oil spills?
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What material is commonly used in modern ship hull construction due to its strength and durability?
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What are the transverse members fitted inside the hull that provide shape and support to the structure called?
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What is the central structural member running along the bottom of the hull from bow to stern called?
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Which of the following is NOT a type of double hull design?
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What is the vertical distance between the waterline and the main deck of the ship called?
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Which of the following statements about bulkheads is true?
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Which part of the ship's hull provides protection to the aftermost (rear) part of the upper deck?
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Which of the following ship structural members runs along the bottom of the hull from bow to stern and forms the backbone of the vessel?
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What is the maximum width of the ship measured perpendicular to its centerline called?
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Which type of hull design is commonly used in oil tankers and provides extra protection against hull puncture and oil spills?
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Study Notes
Camber
- Refers to the slight upward curvature given to a ship's decks or horizontal surfaces to aid in water drainage.
- Directs water towards scuppers to prevent pooling on the deck, crucial during adverse weather conditions.
- Key function includes ensuring safety and efficiency on working and living areas of the ship.
Rise of Floor (Deadrise)
- Represents the rise of the bottom shell plating line above the baseline, measured at the molded beam.
- Notable feature in large cargo ships, which often lack a rise of floor.
Tumblehome
- Describes the inward slope or curvature of a ship's hull near the upper sides, narrowing as it rises above the waterline.
- Opposite of flare; historically common in wooden sailing ships to enhance stability.
- Lowers center of gravity, improving initial stability.
Flare
- Opposite of tumblehome; refers to the outward curvature of the hull as it rises above the waterline.
- Increases buoyancy and enhances stability, especially in rough seas.
- Helps to lift the bow during waves, ensuring a smoother ride.
Sheer
- Indicates the curvature of decks in the longitudinal direction, measured as the height of the deck at the side compared to amidships.
- Prevents wave ingress and is considered when establishing the load line according to international conventions.
Parallel Middle Body
- The straight section of the ship where water lines and buttocks lack curvature, resulting in parallel fore and aft lines.
Midship Section
- The transverse section located halfway between the Forward Post and the After Post, usually the widest part of the ship.
Length Over All (L.O.A.)
- Total length of the ship from one end to the other, including any overhangs at the bow and stern.
Molded Depth
- The vertical distance measured from the top of the keel to the top of the upper deck beams amidships at the gunwale.
Depth
- Height at the midship section from the baseline to the molded line of the deck at the side, indicating hull height.
Draft (Molded)
- The vertical height from the baseline to the load water line, indicating how deep the hull sits in the water.
Freeboard (Molded)
- Difference between molded depth and molded draft, representing the height of the vessel's side above water when floating at the load water line.
Tumble Home
- Describes the slope of the upper section of the ship's side shell leaning inward towards the centerline.
Ship Measurements and Structural Terms
- Length Overall (LOA): Maximum ship length from the forwardmost to the aftermost point, including appendages.
- Length Between Perpendiculars (LBP): Ship length along the waterline, influencing cargo-carrying capacity.
- Beam (B): Maximum width of the ship; important for determining stability.
- Depth (D): Vertical distance from the keel to the uppermost continuous deck of the hull.
- Draught (T): Distance between the waterline and the deepest part of the hull, affecting immersion in water.
- Displacement (DWT or Displ.): Weight of water displaced by the loaded ship, indicating cargo capacity; measured in metric tonnes.
Coefficients and Areas
- Block Coefficient (Cb): Ratio of underwater hull volume to a rectangular block's volume with same dimensions; measures form efficiency.
- Prismatic Coefficient (Cp): Measures underwater volume distribution; ratio to prism volume with the same length and cross-sectional area.
- Midship Section Area (A): Cross-sectional area of the hull at its widest point; relates to buoyancy and resistance.
- Block Ratio (λ): Ratio of max cross-sectional area to a rectangle's area with similar length and beam; indicates hull form characteristics.
Hull Structures and Functions
- Hull structure provides buoyancy, protects cargo and crew.
- Double hull designs (including double bottom and double sides) enhance protection against punctures and oil spills.
- Steel is the primary material used in modern ship hull construction for strength and durability.
- Transverse members (bulkheads, beams, ribs, and frames) support hull shape and structural integrity.
- Keelson runs along the bottom of the hull, adding strength and forming the vessel's backbone; intersects with the keel.
Identifying Ship Components
- Freeboard: Vertical distance between the waterline and the main deck; relevant for ship safety.
- Bulkheads: Internal walls that create compartments within the ship, preventing flooding; not for propulsion.
- Poop Deck: Provides protection at the aftermost part of the upper deck.
- Keel: The central structural member from bow to stern; essential for the hull's integrity.
Types of Hull Design
- Single Hull: Standard hull type; less protection.
- Double Hull: Provides additional safety; preferred for tankers to reduce spillage risks.
- Notable designs include double hull (double bottom) and double hull (double sides); double hull (double top) is not a recognized design.
Quick Reference Questions
- What is the purpose of hull structure? Offers buoyancy and protection.
- What material is used for hull construction? Steel.
- What supports ship shape? Transverse members like bulkheads.
- What does the keel do? Acts as the backbone of the vessel.
- Define beam in ship measurement. The maximum width measured perpendicular to the centerline.
- Correct definition of freeboard. Distance from waterline to main deck.
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Description
This quiz focuses on the concept of camber in the context of ship construction. Students are expected to explain and report on the significance of camber for water drainage on decks and horizontal surfaces. Understanding this concept is essential for grasping OBE principles in maritime education.
