Ship construction Flashcards
FORWARD PERPENDICULAR
(FP)
Vertical line perpendicular to the base line where the summer load line crosses the stem
AFT PERPENDICULAR
(AP)
Vertical line perpendicular to the base line where the summer load line crosses the stern
LENGTH OVERALL
(LOA)
The extreme length of the vessel
LENGTH ON LOAD WATERLINE
(LWL)
The length measured along the current waterline
AMIDSHIPS
The mid - point of the LBP
BEAM
The greatest breadth measured to the outside shell plating.
LENGTH BETWEEN PERPENDICULARS (LBP)
The length of the vessel measured between the forward and aft perpendiculars
DEPTH
The vertical distance between the baseline and the freeboard deck at amidships
DRAUGHT / DRAFT
The vertical distance between the baseline and your current waterline
FREEBOARD
The vertical distance between the uppermost continuous watertight deck (freeboard deck) and the waterline at amidships
ASSIGNED FREEBOARD
The vertical distance between the freeboard deck and the SLL (summer load line) at amidships
REVERSE BUOYANCY
Volume of the enclosed watertight spaces between the load line and the free board deck.
The reverse buoyancy must prevent the deck line submerging when the largest watertight compartment is bilged
CAMBER
Transverse curvature of the deck, helping to shed water from the deck.
SHEER
Longitudinal curvature of deck, adding buoyancy to the ends of the vessel.
FLARE
outward curvature of the bow. Increases buoyancy and keeps the heads dry.
CENTRE LINE
The middle line of the ship extending from the stem to stern at any level.
TRANSVERSE CROSS SECTION
A drawing showing standard cross sections of the hull or near amidships, and showing the scantlings of the main structural members.
SCANTLINGS
The size/strength of structural elements - frames girders, stiffeners, stringers and plates
TONNE
A measurement of weight
1tn = 1000kg
LIGHT DISPLACMENT
Mass of the vessel when complete and ready for sea but with no passengers, stores , fuel or cargo on board. An empty ship
DISPLACMENT
Displacement = underwater volume x relative density of the water
Mass of the vessel floating at any draft between light displacement and summer draft marks.
LOAD DISPLACMENT
Mass of the vessel fully loaded with cargo, stores, etc floating at her assigned freeboard
DEADWEIGHT
Difference between lightship displacement and displacement at any given draft
LOAD / SUMMER DEADWEIGHT
Difference between lightship and summer displacements at the assigned freeboard.
Load displacement - light displacement.
GROSS TONAGE
Internal volume of the ship
NET TONNAGE
Obtained by deducting the non freight spaces (accommodation etc) from the GT
TONNES PER CENTIMETER IMMERSION (TPC)
The mass required to load or discharge in order to change the mean draft by 1cm
LIST THE SIX DIRECTIONS OF MOVEMENT A VESSEL MAY EXPERIENCE
- Yaw
- Sway
- Roll
- Heave
- Pitch
- Surge
SAGGING
When the ends are supported by wave crests and the midships section is unsupported causing the bow and stern to bend upwards.
compression
Neutral Axis
tensile stress
HOGGING
is supported amidships by a wave crest and the ends are unsupported so that the bow and stern droop.
tensile stress
Neutral Axis
compression