Page 22 - Ship Construction.DJ Eyres 6Ed

Ch02-H8070.fm Page 11 Wednesday, October 18, 2006 6:51 AM
Ship Dimensions, Form, Size or Category 11
Moulded dimensions are often referred to; these are taken to the inside
of plating on a metal ship.

Base Line: A horizontal line drawn at the top of the keel plate. All vertical
moulded dimensions are measured relative to this line.
Moulded Beam: Measured at the midship section is the maximum moulded
breadth of the ship.
--- ใช้เพื่อการศึกษาเท่านั้น---
Moulded Draft: Measured from the base line to the summer load line at the
midship section.
Moulded Depth: Measured from the base line to the heel of the upper deck
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี
beam at the ship’s side amidships.
Extreme Beam: The maximum beam taken over all extremities.
Extreme Draft: Taken from the lowest point of keel to the summer load line.
Draft marks represent extreme drafts.
Extreme Depth: Depth of vessel at ship’s side from upper deck to lowest
point of keel.
Half Breadth: Since a ship’s hull is symmetrical about the longitudinal cen-
tre line, often only the half beam or half breadth at any section is given.
Freeboard: The vertical distance measured at the ship’s side between the
summer load line (or service draft) and the freeboard deck. The freeboard
ึ
deck is normally the uppermost complete deck exposed to weather and sea
which has permanent means of closing all openings, and below which all
openings in the ship’s side have watertight closings.
Sheer: Curvature of decks in the longitudinal direction. Measured as the
height of deck at side at any point above the height of deck at side amid-
ships.
Camber (or Round of Beam): Curvature of decks in the transverse direction.
Measured as the height of deck at centre above the height of deck at side.
Rise of Floor (or Deadrise): The rise of the bottom shell plating line above
the base line. This rise is measured at the line of moulded beam.
Half Siding of Keel: The horizontal flat portion of the bottom shell measured
to port or starboard of the ship’s longitudinal centre line. This is a useful
dimension to know when dry-docking.
Tumblehome: The inward curvature of the side shell above the summer
load line.
Flare: The outward curvature of the side shell above the waterline. It promotes
dryness and is therefore associated with the fore end of ship.
Stem Rake: Inclination of the stem line from the vertical.
Keel Rake: Inclination of the keel line from the horizontal. Trawlers and
tugs often have keels raked aft to give greater depth aft where the propeller
diameter is proportionately larger in this type of vessel. Small craft occa-
sionally have forward rake of keel to bring propellers above the line of keel.
Tween Deck Height: Vertical distance between adjacent decks measured from
the tops of deck beams at ships side.