Shipbuilding Materials: Steel, Aluminum, Wood & Testing

• Ships can be made of steel, aluminum alloys, fiber-reinforced plastic (FRP), and wood
• A tensile test measures a material's strength and elasticity
• Steel, especially mild grades, constitutes approximately 90% of the material used in shipbuilding
• Material considerations for ship construction include:
  • Strength
  • Ductility
  • Toughness

Material Strength

• The measure of stress a material can endure

Material Ductility

• The measure of a material’s ability to deform plastically prior to fracture

Material Toughness

• The measure of a material’s ability to absorb energy up to fracture

Ship Building Material

• Metallic
  • Ferrous
    • High tensile steel is for highly stressed regions, such as framing construction
    • Mild steel is for hull construction and shell plating
  • Non-Ferrous:
    • Aluminum
• Non-Metallic
  • Wood
  • Rubber-cement
  • Reinforced fiber-fiberglass

Mild Steel vs High Tensile Steel

• High tensile steel is stronger than mild steel
• Mild steel is more ductile than high tensile steel
• Mild steel is less expensive
• Mild steel is more commonly used for hull construction

Aluminum Alloys vs Steel

• Aluminum is lightweight, corrosion-resistant, and used in high-speed vessels
• Aluminum requires less maintenance than steel

Advantages of Aluminum

• Lighter weight
• Corrosion resistance
• Non-magnetic

Disadvantages of Aluminum

• High cost
• Fatigue stress

FRP vs Steel Hulls

• FRP hulls are lighter than steel
• FRP hulls exhibit corrosion resistance, design flexibility, and thermal insulation

Disadvantages of FRP Hulls

• Low impact resistance
• UV degradation
• High cost
• Low fire resistance

Shell Plate

• Shell plating forms the watertight skin of the ship

Shell Plating Types

• Side shell plating
  • Sheer strake
  • Other strakes on side shell plating
• Bottom shell plating
  • Keel strake and other strakes
  • Garboard strake
• Deck shell plating