Glossary and Definitions Flashcards
Length Overall (LOA)
The Length between the extreme forward and aft points
Length on the Waterline (LWL)
Length along the designed waterline from the furthest aft and forward points
Length Between Perpendiculars (LBP)
Distance on the summer load waterline from the fore side of the stem to the after side of the rudder post.
Breath Moulded (Bmld)
Maximum Breadth measured at midships to the outside of the frameline (inside of plating).
Depth Moulded (Dmld)
Vertical distance at amidships from the keel to the uppermost deck, taken from within the inside of the plating.
Draught Moulded (Tmld)
Vertical distance from the water surface to the inside of the plating at the keel.
‘Even-Keel’
Waterline is parallel to the keel
‘Trimmed by stern’
The draught is greatest at the stern.
‘Trimmed by head’
The draught at the bow is greatest.
Freeboard
Vertical distance from the summer load waterline to the top of the freeboard deck plating measured at amidships.
(Load Line regulations prescribe minimum freeboard)
Extreme dimensions
Measurements taken to the outside of the plating (rather than moulded)
Sheer
Longitudinal curvature of the deck between the ends of the ship.
Sheer Strake
Strake of upper-most continuous shell plating at deck level.
Shell
Outer-plating
Superstructure
Decked structure above the upper deck, the outboard sides of which are formed by shell plating.
Deckhouse
Superstructure found on the upper deck of a ship which doesn’t extend across the full breadth of the ship.
Forecastle Deck
Superstructure at the bow formed by having a raised deck.
Poop Deck
Superstructure at the stern formed by having a raise deck. (The deckhouse normally found on top)
Hatch cover
Cover creating a waterproof closure
Combing
Vertical plating around a hatchway. The height of combing reflects the position and relative exposure of the hatch.
Bulkhead
Vertical transverse or longitudinal division of a ship forming a compartment.
Double-bottom
Longitudinal structure created by a ‘tank-top’ which runs parallel to the bottom shell over the length of the ship. (void along bottom)
6 degrees of freedom
1) heave (vertical), 2) yaw (rotation around heave)
3) surge (forwards/ backwards)) 4) roll (rotation around surge)
5) sway (side to side) 6) pitch (rotation around sway)
Lines Plan
Drawing consisting of the profile, half breadths and body-plan of a ship, illustrating it’s form.
Displacement Stations
Equally spaced divisions along the length between perpendiculars. (O= aft perpendicular)
Hydrostatic Particulars
Properties of the hull form derived from the lines plan. Typically areas, volumes, coefficients of form and centroids. Allow for evaluation of a ships performance and dictate the classification of a ship.
Bonjean Curves
Curves of transverse sectional areas of the ship, drawn along a vertical scale of draught.
Archimedes’ Principle
Upthrust on a body = Weight of fluid displaced
Density of Fresh water
1 tonne/m^3
Density of Sea water
1.025 tonnes/m^3
3 Zones of a Ship
Entrance, Parallel Mid-Body and Run
Entrance
Length of the ship forward of the parallel mid-body
Parallel mid-body
Length of the ship for which the cross section is constant.
Run
Length of the ship aft of the Parallel mid-body
Lightship
Combined mass of unladen ship comprised of three components:
1) Steelmass
2) Mass of main and auxiliary machinery
3) Wood and outfit mass
Deadweight
Mass of payload and consumables
Tonnes per Centimeter Immersion (TPC)
How many tonnes of additional cargo are required to sink the ship 1cm lower into the water. (increase the draught by 1cm)
Tonnage
Indicator of size based on volume.
Gross Tonnage
Indicator of overall size
Net Tonnage
Indicator of carrying capacity
