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navaltoolbox-lib/docs/source/api/python/stability.rst
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Stability
=========
Classes for stability analysis and GZ curve calculations.
StabilityCalculator
-------------------
.. py:class:: StabilityCalculator(vessel, water_density=1025.0)
Calculator for stability analysis (GZ curves).
:param vessel: The vessel to calculate stability for
:param water_density: Water density in kg/m³
.. py:method:: calculate_gz_curve(displacement_mass, cog, heels)
Calculates the GZ curve for a given loading condition.
:param displacement_mass: Base vessel displacement (excluding dynamic tanks) in kg
:param cog: Base center of gravity (LCG, TCG, VCG) excluding dynamic tanks
:param heels: List of heel angles in degrees
:returns: StabilityCurve object with corrected GZ values
.. py:method:: calculate_complete_stability(displacement_mass, cog, heels)
Calculates complete stability analysis combining hydrostatics, GZ curve, and wind data.
:param displacement_mass: Target displacement in kg
:param cog: Center of gravity (LCG, TCG, VCG) tuple
:param heels: List of heel angles for GZ curve in degrees
:returns: CompleteStabilityResult with hydrostatics, GZ curve, and wind data
CompleteStabilityResult
-----------------------
.. py:class:: CompleteStabilityResult
Complete stability calculation result combining hydrostatics, GZ curve, and wind data.
.. py:attribute:: hydrostatics
:type: HydrostaticState
Hydrostatic state at equilibrium (draft, trim, GM0, etc.).
.. py:attribute:: gz_curve
:type: StabilityCurve
GZ stability curve for the loading condition.
.. py:attribute:: wind_data
:type: WindHeelingData or None
Wind heeling data (if silhouettes are defined).
.. py:attribute:: displacement
:type: float
Displacement mass in kg.
.. py:attribute:: cog
:type: tuple[float, float, float]
Center of gravity (LCG, TCG, VCG).
.. py:attribute:: gm0
:type: float or None
Initial transverse metacentric height (GM0) with free surface correction.
.. py:attribute:: gm0_dry
:type: float or None
Initial transverse metacentric height without free surface correction.
.. py:attribute:: max_gz
:type: float or None
Maximum GZ value on the curve.
.. py:attribute:: heel_at_max_gz
:type: float or None
Heel angle at maximum GZ.
.. py:method:: has_wind_data()
Returns True if wind heeling data is available.
:rtype: bool
StabilityCurve
--------------
.. py:class:: StabilityCurve
A complete GZ stability curve.
.. py:method:: heels()
Returns the heel angles.
:rtype: list[float]
.. py:method:: values()
Returns the GZ values.
:rtype: list[float]
.. py:method:: points()
Returns a list of StabilityPoint with (heel, draft, trim, gz, is_flooding, flooded_openings).
Each point has:
- ``heel``: Heel angle in degrees
- ``draft``: Draft at equilibrium (m)
- ``trim``: Trim angle in degrees
- ``gz``: GZ value (m)
- ``is_flooding``: True if any opening is submerged
- ``flooded_openings``: List of flooded opening names
.. py:attribute:: displacement
:type: float
Displacement in kg.
WindHeelingData
---------------
.. py:class:: WindHeelingData
Wind heeling data from silhouette calculations.
Used for wind heeling moment calculations per IMO 2008 IS Code (MSC.267).
.. py:attribute:: emerged_area
:type: float
Total emerged lateral area above waterline (m²).
.. py:attribute:: emerged_centroid
:type: tuple[float, float]
Centroid of emerged area (x, z) in meters.
.. py:attribute:: wind_lever_arm
:type: float
Lever arm from waterline to centroid z coordinate (m).
.. py:attribute:: waterline_z
:type: float
Waterline Z at which calculations were performed.