- Python 3
- The following Python packages: NumPy, MatPlotLib, yaml, scipy
Clone the MoorPy GitHub repository.
To install for development use:
run `python setup.py develop` or `pip install -e .` from the command line in the main MoorPy directory.
To install for non-development use:
run `python setup.py` or `pip install .` from the command line in the main MoorPy directory.
The MoorPy repository has an examples folder containing two example scripts:
- manual_system.py constructs a mooring system from scratch using functions for creating each line and attachment point.
- imported_system.py creates a mooring system by reading an included MoorDyn-style input file.
Running either of these scripts will produce a basic mooring system model that can be used in further analysis.
MoorPy has internal functions to facilitate the orderly creation of a mooring system. The following gives an example of how they work (from manual_system.py).
# ----- choose some system geometry parameters -----
depth = 600 # water depth [m]
angles = np.radians([60, 180, 300]) # line headings list [rad]
rAnchor = 1600 # anchor radius/spacing [m]
zFair = -21 # fairlead z elevation [m]
rFair = 20 # fairlead radius [m]
lineLength= 1800 # line unstretched length [m]
typeName = "chain1" # identifier string for the line type
# ----- set up the mooring system and floating body -----
# Create new MoorPy System and set its depth
ms = mp.System(depth=depth)
# add a line type
ms.setLineType(dnommm=120, material='chain', name=typeName) # this would be 120 mm chain
# Add a free, body at [0,0,0] to the system (including some properties to make it hydrostatically stiff)
ms.addBody(0, np.zeros(6), m=1e6, v=1e3, rM=100, AWP=1e3)
# For each line heading, set the anchor point, the fairlead point, and the line itself
for i, angle in enumerate(angles):
# create end Points for the line
ms.addPoint(1, [rAnchor*np.cos(angle), rAnchor*np.sin(angle), -depth]) # create anchor point (type 0, fixed)
ms.addPoint(1, [ rFair*np.cos(angle), rFair*np.sin(angle), zFair]) # create fairlead point (type 0, fixed)
# attach the fairlead Point to the Body (so it's fixed to the Body rather than the ground)
ms.bodyList[0].attachPoint(2*i+2, [rFair*np.cos(angle), rFair*np.sin(angle), zFair])
# add a Line going between the anchor and fairlead Points
ms.addLine(lineLength, typeName, pointA=2*i+1, pointB=2*i+2)A MoorPy System can be initialized by reading in a MoorDyn-style input file. This is simply done by passing the input file name when creating the System object (from imported_system.py):
ms = mp.System(file='the MoorDyn-style input file.txt')The format of the input file is expected to follow the MoorDyn v2 style, an example of which is shown below:
MoorDyn v2 Input File
Sample for input to MoorPy
---------------------- LINE TYPES --------------------------------------------------
TypeName Diam Mass/m EA BA/-zeta EI Cd Ca CdAx CaAx
(name) (m) (kg/m) (N) (N-s/-) (N-m^2) (-) (-) (-) (-)
chain 0.2160 286.56 1.23e9 -1.0 0.00 1.00 1.00 0.00 0.00
--------------------- ROD TYPES -----------------------------------------------------
TypeName Diam Mass/m Cd Ca CdEnd CaEnd
(name) (m) (kg/m) (-) (-) (-) (-)
----------------------- BODIES ------------------------------------------------------
ID Attachment X0 Y0 Z0 r0 p0 y0 Mass CG* I* Volume CdA* Ca*
(#) (-) (m) (m) (m) (deg) (deg) (deg) (kg) (m) (kg-m^2) (m^3) (m^2) (-)
1 coupled 0.00 0.00 -0.75 0.00 0.00 0.00 1.0e6 0.00 0.00 1.0e3 0.00 0.00
---------------------- RODS ---------------------------------------------------------
ID RodType Attachment Xa Ya Za Xb Yb Zb NumSegs RodOutputs
(#) (name) (#/key) (m) (m) (m) (m) (m) (m) (-) (-)
---------------------- POINTS -------------------------------------------------------
ID Attachment X Y Z Mass Volume CdA Ca
(#) (-) (m) (m) (m) (kg) (mˆ3) (m^2) (-)
1 Fixed 800.00 1385.64 -600.00 0.00 0.00 0.00 0.00
2 Body1 10.00 17.32 -21.00 0.00 0.00 0.00 0.00
3 Fixed -1600.00 0.00 -600.00 0.00 0.00 0.00 0.00
4 Body1 -20.00 0.00 -21.00 0.00 0.00 0.00 0.00
5 Fixed 800.00 -1385.64 -600.00 0.00 0.00 0.00 0.00
6 Body1 10.00 -17.32 -21.00 0.00 0.00 0.00 0.00
---------------------- LINES --------------------------------------------------------
ID LineType AttachA AttachB UnstrLen NumSegs LineOutputs
(#) (name) (#) (#) (m) (-) (-)
1 chain 1 2 1800.000 40 p
2 chain 3 4 1800.000 40 p
3 chain 5 6 1800.000 40 p
---------------------- OPTIONS ------------------------------------------------------
600.0 depth
--------------------- need this line ------------------------------------------------
Note that some parameters are only applicable to a dynamic model like MoorDyn, and are ignored by MoorPy. Conversely, some Body parameters used by MoorPy for hydrostatics are not captured in a MoorDyn-style file.
Once the MoorPy System is set up, it can be analyzed, viewed, and manipulated using a handful of main functions, as well as a variety of additional helper functions for more specialized tasks.
Here is an example showing one of the possible functions to analyze a mooring system:
ms.initialize() # make sure everything's connected
ms.solveEquilibrium() # equilibrate
fig, ax = ms.plot() # plot the system in original configuration
ms.unload("sample.txt") # export to MD input file
ms.bodyList[0].f6Ext = np.array([3e6, 0, 0, 0, 0, 0]) # apply an external force on the body
ms.solveEquilibrium() # equilibrate
fig, ax = ms.plot(ax=ax, color='red') # plot the system in displaced configuration (on the same plot, in red)Documentation Overview
An overview of how a mooring system is represented in MoorPy can be found in :ref:`The Model Structure page<Model Structure>`.
More documentation and examples of other functions that can be applied to a MoorPy mooring system can be found in :ref:`The Usage page<MoorPy Usage>`.
Detailed theory "under the hood" of the functions in MoorPy can be found in :ref:`The Theory Page<Theory and References>`.
Detailed inputs and outputs of MoorPy classes and functions can be found in :ref:`The API Page<API>`.