Transcript PLANES- DIMENSIONS

ΕΥΣΤΑΘΕΙΑ
ΒΑΣΙΚΕΣ ΑΡΧΕΣ
STABILITY
STABILITY
GEOMETRICAL
WEIGHT
MANUALS
MANUALS
STATICAL
OR
DYNAMIC
DAMAGE
INTACT
LONGITUDINAL
TRANSVERSE
LIST < 10O
LIST > 10O
PLANES- DIMENSIONS
Longitudinal plane
 Transverse plane
 Horizontal plane
 Waterplanes
 Fore perpendicular
 Aft perpendicular
 Hull – Shell
 Base line
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Designed waterline
Length btn perprs
Length water line
Length over all
Sheer Fore – Aft
Camber
Freeboard
Beam
Rise of floor
DRAFTS
Fore draft
 Aft draft
 Mean draft
 Even keel
 Trim by bow stern


Draft correction
TERMINOLOGY
Light ship
 Light waterline
 Wetted surfase
 Loadline
 Displasement
 Light displacement
 Full load displ.
 Waterlinezone

Center of gravity
 Center of volume
 Center of buoyancy
 Form coefficients
 Superstructure
 Deck erection
 Bulkheads
 Tonnage

SIMPSON RULES
 First
rule: h/3 ( a + 4b + 2c + 4d +
e)
Used when an odd number of ordinates are taken
 Second rule:
3h/8 ( a + 3b + 3c + 2d + 3e + 3f +
g)
The rule can be used when the number of ordinates is
four, or four plus some multiple of three (e.g. 4,7,10,13,16, etc)
 Five
eight rule: h/12 ( 5x + 8y – z)
This may be used to find the area between two consecutive ordinates. We
must know the length of one other ordinate, next to the area we wish to
measure.
DEFINITIONS
 Angle
of vanishing stability :
The angle at
which a ship’s stability becomes 0 . Numerically the same as the range of
stability.
 Center
of buoyancy :
 Center
of flotation :
 Center
of gravity :
The geometrical center of the
underwater part of the ship.
The point about which the ship
heels and trims. The center of gravity of the waterplane.
The center of all the weight in a
body. The point about which the body would balance.
 Deadweight
ih a ship.
:
The weight of all cargo, stores, bunkers, etc,
More definitions
 Deadweight
moment :
The total moment about the
base line of all the components of deadweight.
 Displacement
aboard her at any time.
:
The actual weight of the ship and all
 Draft
:
 Draft
mean : The mean of the drafts fore and aft, as it would
 Draft
at F :
water.
The depth of the bottom of the keel below the surface of the
be measured amidships.
center og flotation.
The ship’s draft measured at the position of the
More definitions
 Dynamical
stability :The amount of work done in
inclining a ship to any given angle of heel.
 Fluid
KG or GM :
The ship’s KG or GM, after allowance
has been made for the effect of free surface of liquids.
 Freeboard
: The distance from the deck line to the water.
 Fresh water allowance : The amount by which the
ship would increase her draft on passing from salt to fresh water.
 Height
of metacenter :
above the keel
The height of metacenter
More definitions
 Inertia
motion.
 Initial
:
The resistance of a body to motion or to change of
stability :
The statical stability of a ship at a small
angle of heel. Indicated by GM.
 KG
:
 KN :
The height of the center of gravity above the keel.
The righting lever which the ship would have if G were placed at
the keel.
 Law
of Archimedes :
A body immersed in a liquid
appears to suffer a loss in weight equal to the weight of liquid which it
displaces. From this law we conclude that a floating body displaces its own
weight of water.
More definitions
 Light
displacement :
The displacement of a ship when
she’s floating at her designed light draft. The weight of the hull,
machinery, spare parts and water in the boilers.
 Loaded
displacement :
The displacement of a ship
when she is floating at her designed summer draft. The light displacement
plus the dead weight.
 Longitudinal
metacentric height :
The
height of the longitudinal metacenter above the center of gravity.
 Mean
draft : The mean of the ship’s drafts fore and aft.
 Metacenter : The point at which the vertical line through the
center of buoyancy, at a small angle of heel, cuts the ships center line. It
is only considered to exist for angles of heel up to about 15o .
More definitions
 Metacentric
height :
The height of the transverse
metacentre above the center of gravity.
 Moment
:
 MTC-1
The moment to change the ship’s trim by one
The attempt of a force to turn a body. It is usually
measured by the product of the force and the length of the lever.
centimeter.
:
 Moment
of statical stability :
The moment
which will try to return a ship to the upright when she’s inclined.
 Period
of a ship :
The time taken by a ship to roll from
one side to the other and back again.
More definitions
 Solid
KG or GM :
The ships KG or GM neglecting the
effect of free surface of liquids.
 Stiff
ship :
A ship which has a large moment of statical stability.
One having a large metacentring height, or righting lever.
 Synchronism
:
Said to occur when a ship’s period of roll is
the same as that of the waves.
 Tender
ship :
A ship which has a small moment of statical
stability. One having a small metacentric height or righting lever.
 TPC
:
Tones per centimeter of immersion. The weight which must be
added to a ship in order to cause her to sink one centimeter bodily.
More definitions
 Period
of waves :
 Range
of stability :
The interval between the passages of
any two consecutive wave crests.
The angular range over which a
ship will have positive statical stability. The angle to which the ship would
heel before she would tend to capsize.
 Reserve
buoyancy :
 Righting
lever : The perpendicular distance between the
The volume of the ship’s hull
between the water plane and the freeboard deck.
center of gravity and the vertical line through the center of buoyancy. The
lever of the ends of which the weight of the ship acts to turn her to the
upright when she is heeled.