Ship Structure and Nautical Terms

Parts of a Ship

• Hull

  • Main body of the ship.
  • Divided into three parts:
    • Forward part
    • Midship part
    • Aft part
  • Forward part ends at the stem; Aft part ends at the stern.

• Fore and Aft Line

  • Imaginary line running along the ship's length from stem (forward) to stern (aft).
  • Important for dividing the ship into right (starboard) and left (port) sides.
  • Board numbers: Odd on starboard, even on port side.

Hull Surfaces

• Keel

  • Lowermost part of the ship; considered the backbone.

• Bow

  • Curved surface of the forward part.

• Midship

  • Center part of the ship.

Water Line

• Line where the ship floats.
• Above water line: Ship's side.
• Below water line: Bottom of the ship.

Decks

• Continuous horizontal surfaces.
  • Types include bottom platform, middle deck, main deck, upper deck.
  • Weather deck is exposed to the elements.
  • Difference between decks and platforms/flats: Decks are continuous, flats are not.
  • Specific decks:
    • Forecastle deck (in the forward part)
    • Poop deck (in the aft part)

Terms Related to the Hull

• Freeboard

  • Height of the highest continuous watertight deck above the water line.

• Draft

  • Depth of the keel below the water line.

• Breadth

  • Extreme Breadth: Maximum beam measured from outside edge of shell plating.
  • Molded Breadth: Measured inside the edge of shell plating.

• Camber

  • Curvature of the deck in the port-starboard direction, helping to drain water.

• Depth

  • Extreme Depth: Measured from outside.
  • Molded Depth: Measured from inside.

• Shear

  • Curvature of the deck in the fore-aft direction.
  • Forward Shear: In the forward direction.
  • Aft Shear: In the aft direction.

• Flare

  • Outward curvature of shell plating in the forward part, providing more width to forecastle and preventing water from coming on board.