Ship Parts Flashcards
BEAM (B) -
The breadth of the ship at the widest point. Molded beam
is measured amidships or at the widest section from the inside surface
of the shell plating.
CAMBER
The convex upwards curve of a deck from the sides
towards the centreline. Also called round up, round down, or round of
beam.
DRAFT (d)
The depth from waterline to the deepest part of the ship
DEPTH (D)
Total depth from bottom to the top watertight deck.
Depth = freeboard + draft.
Freeboard (F)
Distance between the waterline and the uppermost
watertight deck.
TUMBLEHOME
Inward slope of hull sides above the waterline - the
opposite of flare. Tumblehome was a usual feature in sailing ships and
many ships built before 1940. Only seen on tugs and icebreaking vessels,
sometimes used to reduce topside weight, and for reducing radar cross
sections.
FLARE
The outward curvature of the hull surface above the
waterline, i.e., the opposite of tumblehome. Increases buoyancy when
immersed. Flaring bows are often fitted to help keep the forward decks
dry and to prevent “nose-diving” in head seas.
RISE OF FLOOR/DEADRISE —-
Rise of the bottom from baseline to
molded breadth measureed amidships. Full-bodied ships, such as cargo
ships and tankers, have little or no deadrise, while fine-lined ships have
much greater deadrise along with a large bilge radius.
Gross tonnage
is the capacity (volume) of the
enclosed spaces above and below the main
deck.
Net tonnage
is the gross tonnage less the
volume of spaces used for accommodation,
navigation, propulsion, ballast and workshops.
Essentially, the space available for cargo.
1 Register Ton
2.83m3 or 100ft3
BASELINE (BL)
An imaginary horizontal line, drawn through the
upper edge of the keel, from which rise of floor and other vertical
measurements may be taken.
DESIGN (loaded) WATERLINE (DWL)
The waterline at which the ship
will float in her designed loaded condition (Summer – Saltwater)
LENGTH ON WATERLINE (LWL)
The length at the waterline when the
ship is loaded to its designed draft (Summer – Saltwater).
FORWARD PERPENDICULAR (FP)
- A vertical line at the point where
the DWL crosses the foremost part of the stem (bow).
AFTER PERPENDICULAR (AP) -
A vertical line usually at the after end
of the rudder post. If there is no rudder post, it usually is taken at the
center of the rudder stock.
LENGTH BETWEEN PERPENDICULARS (LBP)
The distance from the
forward perpendicular to the after perpendicular. . It is constant for a
given ship and does not depend on the loading condition of the ship.
To the designers, this length is very important, since it largely
determines the amount of power needed to drive the ship.
LENGTH OVER ALL (L.O.A.)
The total length of the ship from one
end to the other, including bow and stern overhangs.
SHEER
The rise of the deck – usually toward bow or stern. It
increases freeboard and helps keep the vessel from shipping water in
rough seas, especially at the bow.
