20. Simulate an advanced single leg mooring

The identification tag for this tutorial is PDS-AAT. Pregenerated input files for this tutorial are found in the folder named PDS-AAT in the provided tutorial input files.

20.1. Tutorial overview

The following tutorial reviews the setup of a complete single point oceanographic mooring for users of ProteusDS (LE compatible).

The tutorial covers:

  • Mooring components with Extmass
  • Different mooring materials
  • Steady state analysis
  • Export results to a new simulation
  • Convert QuasiStaticCable to Cable
  • Dynamic waves
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Fig. 20.1 Single point mooring in PostPDS.

20.2. Introduction

The oceanographic mooring design to be modeled in ProteusDS is from the University of Washington Applied Physics Laboratory. A mooring diagram can be found here, and seen in Fig. 20.2 (with components numbered). This mooring was chosen because it provides a typical example of an actual oceanographic mooring complete with several different types of components and line types.

20.3. Creating a QuasiStaticCable DObject and setting the end conditions

  • Open ProteusDS Simulation Toolbox (PST) and save the new project in the desired folder location.
  • Add a QuasiStaticCable DObject and name the cable DObject Mooring.

When modeling single point moorings in ProteusDS, the anchor end of the mooring is typically fixed. After the simulation is run, the forces acting on the anchor end of the mooring are reported such that the anchor size can be calculated. For this example, cable end node 0 will be set to be the anchor end. Therefore, the order in which components and cable materials will be listed will be relative to the anchor end.

  • Set the $Node0Static 1 flag to set node 0 to be fixed. The default flag $NodeNStatic 0 should also be set to ensure that node N, which will be the surface end of the mooring, is free.
  • Add the $Node0Anchor 1 flag to the Mooring input file. This flag tells the ProteusDS solver to output additional data used when designing moorings, including grounded line length and uplift angle at node 0.

20.4. Adding mooring components

All mooring components will be modeled using ExtMass or ExtMassCylinder features. These features will represent sphere or cylinder shapes with different mass, buoyancy, and drag characteristics. The properties will reside in the library so that the same feature can be reused multiple times on the cable whilst remaining defined and editable in a single location.

The data sheets for each of the mooring components can be found in Section 20.11.

20.4.1. Adding acoustic release

An acoustic release is located 2 m from the anchor for this mooring. The acoustic release is specified as ORE8242xs. To determine the size and weight in water of the acoustic release, the spec sheet can be found here, and can be seen in Figure 21.3.

  • Add the property $ExtMassCylinder AcousticRelease 2.473 to the Mooring cable file.

This property adds an ExtMassCylinder to the cable. The name of the ExtMassCylinder is AcousticRelease and the ExtMassCylinder is positioned at an arc length of 2.473 m (relative to the cable node 0, which is the anchor). An arc length of 2.473 m is used to account for the 2 m of chain between the anchor and the acoustic release and 50% of the length of the acoustic release. In ProteusDS ExtMassCylinder features are attached to the cable in one location (at the center of the ExtMassCylinder) and therefore the arc length must be set to account for half of the acoustic release length.

  • Right click on the ExtMassCylinder property and click the Go to feature definition option. Click create on the following window to automatically create the library entry.

Note

  • When the ExtmassCylinder property is selected, pressing F12 will also prompt PST to go to the feature definition.
  • In the AcousticRelease library entry, set the $ExtMassType property to 1.

The property $ExtMassType 1 allows the user to set the mass in air and mass in water instead of setting the material density. As the mass in air and water were provided by the spec sheet, this method will be used to set the properties.

  • Select the $ExtMassType 1 property and press Ctrl-R to remove (using // comments) any property entries that are no longer required and add the properties that are now required.
  • Set the properties based on the values provided by the data sheet.

The data sheets are shown in Fig. 20.4.

The AcousticRelease feature entry should look like the following:

// Fluid loading
$CD 0.78
$CA 0.5
$FluidLoadingMode 0
$CDAxial 0.85

// Mechanical
$Diameter 0.13
// $Density 1025
$Length 0.946

// Type
$ExtMassType 1
$ApparentMassWaterDensity 1025
$ApparentMassInWater 28
$Mass 36

For this tutorial it is assumed that all spec sheets used saltwater for the weight in water measurement (it may be important to verify this with manufacturers). If weight in fresh water is known $WeightInWaterDensity can be set to 1000. The drag for a cylinder can vary depending on its aspect ratio, so it is advised for users to check the normal drag coefficients using a fluid dynamics handbook prior to accepting defaults.

20.4.2. Adding submerged buoys

This mooring contains 4 separate submerged buoys. Two are identical 3x12” glass floats, one is a 30” steel float, and one is a 37” steel float.

The glass floats are specified as G6600. The spec sheet was found online here, and can be seen in Fig. 20.5. As the glass floats are the same, only one library entry is created and can be referenced twice in the cable input file.

  • Add the property $ExtMassCylinder GlassFloats 3.946 to the cable input file.

This distance was calculated from the mooring schematic by adding the length of components 2 through 4. An additional 0.5 m was added as the glass floats are specified to be connected to the mooring using 1 m of chain (similar to adding 50% of the acoustic release length to the AcousticRelease feature arc length).

The three glass floats will be modeled as a single cylinder in ProteusDS. This will ensure that the correct frontal area of the floats is being used for hydrodynamic calculations.

  • Create the GlassFloats library entry and set the properties based on the values provided by the data sheet.

The feature entry should look like the following:

// Fluid loading
$CD 0.64
$CA 0.5
$FluidLoadingMode 0
$CDAxial 1.10

// Mechanical
$Diameter 0.657
// $Density 1025
$Length 0.305

// Type
$ExtMassType 1
$ApparentMassWaterDensity 1025
$ApparentMassInWater -30
$Mass 21

The diameter is calculated from three individual 12” (0.305 m) floats beside each other. The cylinder length dimension is the height of the three floats.The $WeightInWater property is set to -30. This value is the buoyancy of 66 lbs converted into kg. The value is negative to specify that the object is buoyant.

In reality the drag will be slightly different as it is acting on three sphere hardhats and not on a cylinder. For this simulation, a cylinder approximation will suffice as further drag data is not available.

  • Add the property $ExtMassCylinder GlassFloats 5.946 to the cable input file below the previous ExtMassCylinder entry.

The arc length 5.946 m was calculated by the length of components 2 through 6. An additional 0.5 m was added as the glass floats are specified to be connected to the mooring using 1 m of chain. As this feature has already been created and added to the library, it does not need to be created again.

  • Add the property $ExtMass SteelFloat30in 4135.3 to the cable.

The arc length of 4135.3 m was calculated by adding the length of components 2 through 12 plus half the diameter of the 30” steel float. The spec sheet for the 30” steel float was found online here, and can be seen in Fig. 20.6.

  • Create the SteelFloat30in library entry and set the properties based on the values provided by the data sheet.

The library entry should look like the following:

// Fluid loading
$CD 0.5
$CA 0.5
$FluidLoadingMode 0

// Mechanical
$Diameter 0.762
// $Density 1025

// Type
$ExtMassType 1
$ApparentMassWaterDensity 1025
$ApparentMassInWater -167.4

$Mass 75

The $WeightInWater property is set to -167.4. This value is 369 lbs converted into kg. The negative indicates that the object is buoyant.The default drag and added mass properties will be used.

  • Add the property $ExtMass SteelFloat37in 4136.7 to the cable.

The spec sheet for the 37” steel float was found online here, and can be seen in Fig. 20.6.

  • Create the SteelFloat37in library entry and set the properties based on the values provided by the data sheet.

The library entry should look like the following:

// Fluid loading
$CD 0.5
$CA 0.5
$FluidLoadingMode 0

// Mechanical
$Diameter 0.94
// $Density 1025

// Type
$ExtMassType 1
$ApparentMassWaterDensity 1025
$ApparentMassInWater -318
$Mass 137

The two small floats on the Polypropylene line (component 15) will be ignored for the purpose of this tutorial. The location, diameter, and weight in air is not provided in the mooring schematic.

20.4.3. Adding the surface buoy

The mooring schematic shows that the WaveRider MKIII was used as a surface buoy for this mooring. The spec sheet for this buoy is found here, and can be seen in Fig. 20.7. The process for adding the surface buoy is identical to adding submerged buoy. An ExtMass feature will be created to model a spherical object.

  • Add the property $ExtMass WaveRider 4469.8 to the cable.

The arc length of 4469.8 m was calculated by adding the length of components 2 through 21 plus half the diameter of the WaveRider float.

  • Create the WaveRider library entry and set the properties based on the values provided by the data sheet.

The library entry should look like the following:

// Fluid loading
$CD 0.5
$CA 0.5
$FluidLoadingMode 0

// Mechanical
$Diameter 0.9
$Density 592

// Type
$ExtMassType 0

For this library feature, the $ExtMassType property will be left as 0. No weight in water is provided in the data sheet, therefore to accurately model the mass and buoyancy of the float a characteristic density will be calculated using the known weight in air and the volume of the sphere. The buoy density was calculated using the provided weight in air of 225 kg from the spec sheet and the diameter of the sphere of 0.9 m. The property $FluidLoadingMode 1 is used to enable the variable hydrodynamic loading algorithm. This is used for objects on the water surface that will have variable buoyancy.

Note

  • Ensuring that the variable hydrodynamic loading algorithm is turned off for objects that will never pierce the water surface will increase computational speed.

20.4.4. Adding shackles and swivels

The shackles and swivels in this mooring can be modeled using ExtMass and ExtMassCylinder features. The drag on the system and length added to the mooring from the shackles will not be significant as it is very small in relation to the size of the mooring. However, the mass of the shackles and swivels needs to be considered as it will effect the buoyancy of the system. The thimbles weigh approximately 0.3 lbs and therefore can be ignored for the purposes of the simulation. If the torsional stiffness GJ of the chain is set to 0, then the model allows the cable to rotate freely - which effectively models a swivel in the mooring. Additionally, torsional effects in cables are ignored when modeling moorings as pinned/frictionless connections are used at the seabed. Therefore, only the mass contribution of the swivel needs to be modeled.

  • Add the property $ExtMass Shackle0.625in 0 to the cable.

The arc length 0 represents the first shackle between the anchor and the first length of chain. A spec sheet for shackles is found here, and can be seen in Fig. 20.8.

  • Create the Shackle0.625in library entry and set the properties based on the values provided by the data sheet.

The library entry should look like the following:

// Fluid loading
$CD 0.5
$CA 0.5
$FluidLoadingMode 0

// Mechanical
$Diameter 0.043
// $Density 1025

// Type
$ExtMassType 1
$ApparentMassWaterDensity 1025
$ApparentMassInWater 0.62

$Mass 0.714

It was determined from the spec sheet that a 5/8” shackle weighs 0.714 kg. Using the known density of steel, this results in a weight in water of 0.620 kg. The $Diameter property was set to 0.043. This dimension is the outside eye diameter 1.69” converted into meters. The default drag and added mass properties will be used. The drag on such a small component will be insignificant to the model.

  • Add the shackles to the cable input file at arc lengths: 0, 2, 2.946, 2.946, 2.946, 3.446, 4.446, 6.946, 6.946, 4081, 4083, 4135, 4135.5, 4135.5, 4136.3, 4136.3, 4136.3, 4136.3, 4137.2, 4137.2, 4137.2, 4325.2, 4326, 4438, 4438.5, 4468.5, 4468.5, 4469.5.

The section of shackle features in the cable input file should look like the following:


$ExtMass Shackle0.625in 0
$ExtMass Shackle0.625in 2
$ExtMass Shackle0.625in 2.946
$ExtMass Shackle0.625in 2.946
$ExtMass Shackle0.625in 2.946
$ExtMass Shackle0.625in 3.446
$ExtMass Shackle0.625in 4.446
$ExtMass Shackle0.625in 6.946
$ExtMass Shackle0.625in 6.946
$ExtMass Shackle0.625in 4081
$ExtMass Shackle0.625in 4083
$ExtMass Shackle0.625in 4135
$ExtMass Shackle0.625in 4135.5
$ExtMass Shackle0.625in 4135.5
$ExtMass Shackle0.625in 4136.3
$ExtMass Shackle0.625in 4136.3
$ExtMass Shackle0.625in 4136.3
$ExtMass Shackle0.625in 4136.3
$ExtMass Shackle0.625in 4137.2
$ExtMass Shackle0.625in 4137.2
$ExtMass Shackle0.625in 4137.2
$ExtMass Shackle0.625in 4325.2
$ExtMass Shackle0.625in 4326
$ExtMass Shackle0.625in 4438
$ExtMass Shackle0.625in 4438.5
$ExtMass Shackle0.625in 4468.5
$ExtMass Shackle0.625in 4468.5
$ExtMass Shackle0.625in 4469.5

  • Add the property $ExtMassCylinder Swivel3ton 2.946 to the cable.

The arc length 2.946 represents the first swivel after the acoustic release.

A spec sheet for swivels is found here, and can be seen in Fig. 20.9. It was assumed that the swivel type was eye & eye.

  • Create the Swivel3ton library entry and set the properties based on the values provided by the data sheet.

The library feature should look like the following:

// Fluid loading
$CD 1
$CA 0.5
$FluidLoadingMode 0
$CDAxial 0.93

// Mechanical
$Diameter 0.07
// $Density 1025
$Length 0.24

// Type
$ExtMassType 1
$ApparentMassWaterDensity 1025
$ApparentMassInWater 3.35
$Mass 3.86

It was determined from the spec sheet that a 3 ton swivel weighs 3.86 kg. Using the known density of steel, this results in a weight in water of 3.35 kg.

  • Add the swivels to the cable at arc lengths: 2.946, 6.946, 4468.5.

The section of swivel features in the cable input file should look like the following:


$ExtMassCylinder Swivel3ton 2.946
$ExtMassCylinder Swivel3ton 6.946
$ExtMassCylinder Swivel3ton 4468.5
  • The cable input file should look like the following:
// Boundary constraints
$Node0Static 1
$NodeNStatic 0
$Node0Anchor 1

$CableSegmentMode 1

$ExtMassCylinder AcousticRelease 2.473
$ExtMassCylinder GlassFloats 3.946
$ExtMassCylinder GlassFloats 5.946
$ExtMass SteelFloat30in 4135.3
$ExtMass SteelFloat37in 4136.7

$ExtMass WaveRider 4469.8

$ExtMass Shackle0.625in 0
$ExtMass Shackle0.625in 2
$ExtMass Shackle0.625in 2.946
$ExtMass Shackle0.625in 2.946
$ExtMass Shackle0.625in 2.946
$ExtMass Shackle0.625in 3.446
$ExtMass Shackle0.625in 4.446
$ExtMass Shackle0.625in 6.946
$ExtMass Shackle0.625in 6.946
$ExtMass Shackle0.625in 4081
$ExtMass Shackle0.625in 4083
$ExtMass Shackle0.625in 4135
$ExtMass Shackle0.625in 4135.5
$ExtMass Shackle0.625in 4135.5
$ExtMass Shackle0.625in 4136.3
$ExtMass Shackle0.625in 4136.3
$ExtMass Shackle0.625in 4136.3
$ExtMass Shackle0.625in 4136.3
$ExtMass Shackle0.625in 4137.2
$ExtMass Shackle0.625in 4137.2
$ExtMass Shackle0.625in 4137.2
$ExtMass Shackle0.625in 4325.2
$ExtMass Shackle0.625in 4326
$ExtMass Shackle0.625in 4438
$ExtMass Shackle0.625in 4438.5
$ExtMass Shackle0.625in 4468.5
$ExtMass Shackle0.625in 4468.5
$ExtMass Shackle0.625in 4469.5

$ExtMassCylinder Swivel3ton 2.946
$ExtMassCylinder Swivel3ton 6.946
$ExtMassCylinder Swivel3ton 4468.5

20.5. Setting cable materials

To set the cable properties for various sections of the mooring, DCableSegment features must be created for each material. For this tutorial, all required DCableSegment features will be created first and then the features will be added to the cable. This will demonstrate an alternate order for setting up simulation files. If desired, the features can be created as they are added to the cable input file similar to the method used for creating and adding the objects in the previous section.

20.5.1. Creating 1/2” chain feature

  • Create a new DCableSegment feature called Chain0.5in.

It was assumed that the chain used was R3 studless chain as chain grade data was not provided in the schematic. 14mm chain was used instead of 13mm chain, as the chain spec sheet does not contain 13mm chain. The method for determining the chain properties is outlined in the Chain properties tutorial. The specs for R3 studless chain can be found here. The data sheet can be found in the Chain properties tutorial.

Note

  • The Cable Properties Wizard can be used to calculate the chain properties. The Cable Properties Wizard can be found here.

The Chain0.5in feature entry should look like the following:

// Axial Rigidity
$AxialRigidityMode 0
$EA 5E5

// Fluid loading
$FluidDiameter 1.4E-2
$CDc 2.2
$CDt 1.15
$CAc 1

//Mechanical
$EI1 0
$EI2 0
$GJ 0
$Diameter 2.213E-2
$Density 7800
$AxialDampingMode 1
$AxialReferenceDampingRatio 0.5
$BCID 0
$TCID 0
$CE 1

// Strain Limit
$ElongationLimitMode 0

20.5.2. Creating CoPoly rope feature

  • Create a new DCableSegment feature called CoPoly0.625in.

The method for determining the fiber rope cable properties is outlined in the Fiber rope cable properties tutorial . The specs for Yale Cordage luggar line can be found here, and can be seen in Fig. 20.10.

The CoPoly0.625in feature entry should look like the following:

// Axial Rigidity
$AxialRigidityMode 0
$EA 3.607E5

// Fluid loading
$CDc 1.5
$CDt 0.045
$CAc 1

//Mechanical
$EI1 5.772E0
$EI2 5.772E0
$GJ 5.772E0
$Diameter 1.6E-2
$BuoyancyDiameter 1.365E-2
$Density 676.4
$AxialDampingMode 1
$AxialReferenceDampingRatio 0.5
$BCID 0
$TCID 0
$CE 1

// Strain Limit
$ElongationLimitMode 0

20.5.3. Creating wire rope feature

  • Create a new DCableSegment feature called WireRope0.375in.

It was assumed that the wire rope was 6x19 IWRC IPS wire rope. It was assumed that the jacket does not effect the weight or diameter of the cable. The method for determining the wire rope cable properties is outlined in the Wire rope cable properties tutorial. The specs for 6x19 IWRC IPS wire rope can be found here. The data sheet can also be found in the Wire rope cable properties tutorial.

The WireRope0.375in feature entry should look like the following:

// Fluid loading
$CDc    1.5
$CDt     0.045
$CAc    1

//Mechanical
$EA     4.988E6
$EI1    2.828E1
$EI2    2.828E1
$GJ    2.828E1
$Diameter   9.525E-3
$BuoyancyDiameter   7.947E-3
$Density    5429.5
$AxialDampingMode 1
$AxialReferenceDampingRatio 0.5
$BCID   0
$TCID   0
$CE     1

20.5.4. Creating Polypropelene rope feature

  • Create a new DCableSegment feature called PolyRope22mm.

It was assumed that the polypropylene rope used was 22 mm Taurus 8-strand plaited polypropylene rope. The size or strand type was not provided in the schematic, the size of the rope was determined based on the size and strength of other components in the mooring line. It was assumed that the specific gravity for polypropylene rope is 0.91. The properties for Taurus 8 strand rope can be seen in Fig. 20.11.

The polypropylene rope feature entry should look like the following:

// Axial Rigidity
$AxialRigidityMode 0
$EA 2.453E3

// Fluid loading
$CDc 1.5
$CDt 0.045
$CAc 1

//Mechanical
$EI1 1.878E-1
$EI2 1.878E-1
$GJ 1.878E-1
$Diameter 3.5E-2
$BuoyancyDiameter 3.505E-2
$Density 1579.9
$AxialDampingMode 1
$AxialReferenceDampingRatio 0.5
$BCID 0
$TCID 0
$CE 1

// Strain Limit
$ElongationLimitMode 0

20.5.5. Creating rubber cord rope feature

    • Create a new DCableSegment feature called RubberCord35mm.

It was assumed that the rubber cord used was 35 mm with a hardness of 45 shore A. The method for determining the fiber rope cable properties is outlined in the Fiber rope cable properties tutorial. The specs for rubber cord can be found here, and can be seen in Fig. 20.12. The specific gravity is not provided in the spec. Specific gravities for various rubber cords were found here, and can be seen in Fig. 20.13. The specific gravity used for this rubber cord was 1.575. Using this value, the density of the rubber cord can be calculated. Using the density and the known volume of the chord, an approximate weight in air can be calculated. The approximate weight in air for 1 m of rubber cord was calculated to be 1.52 kg.

The RubberCord35mm feature entry should look like the following:

// Axial Rigidity
$AxialRigidityMode 0
$EA 2.453e3

// Fluid loading
$CDc 1.5
$CDt 0.01
$CAc 1

// Mechanical
$EI1 1.878e-1
$EI2 1.878e-1
$GJ 1.878e-1
$Diameter 3.5e-2
$BuoyancyDiameter 3.505e-2
$Density 1579.9
$CID 1e3
$BCID 0
$TCID 0
$CE 1

// Strain Limit
$ElongationLimitMode 0

20.6. Setting the state of the mooring and the cable element lengths

To model the mooring in ProteusDS, the user must state where both ends of the cable are in space and the user must set the length of each cable element.For the initial simulation, the cable will be placed in a straight line from the anchor to the surface. The mooring schematic specifies the depth of the mooring to be 4255m. The total mooring length is 4469.8 m. Therefore, it can be determined that if the mooring is to be in a straight line, the surface float must be 1368.97 m away from the anchor in the horizontal plane.

  • Set the anchor at the simulation origin by entering the following values for node 0: X: 0, Y: 0, Z: 4255.
  • Set the surface float at the straight line distance away from the anchor by entering the following values for node N: X: 1368.97, Y: 0, Z: 0.
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Fig. 20.3 Initial mooring state

  • In the environment input file, set the $WaterDepth property to 4255.

The number of cable elements will have a significant effect on the simulation run time. By ensuring that not too many cable elements are used, the user can reduce the run time significantly. The amount of cable elements required in the simulation depends on a number of factors. If the surface buoy is moving in waves, higher cable resolution may be desired near the surface of the mooring. If a finely detailed current profile is being used, more cable elements may be required to accurately sample the current velocity at more depths.

For this mooring, around 80 cable elements will be used. If the simulation is running too slowly, or if more resolution is desired, the number of elements can be adjusted.

  • Define the segments as shown in the cable state generator segments list table below to recreate the mooring.
Table 20.1 Cable State Generator Segments List
Segment type Unstretched length (m) Number of elements Element lengths (m) Arc length from Node 0 (m)
Chain0.5in 6.946 1 6.946 0
CoPoly0.625in 4074 35 116.4 6.946
WireRope0.375in 2 1 2 4080.946
CoPoly0.625in 52 5 10.4 4082.946
Chain0.5in 2.202 1 2.202 4134.946
PolyRope22mm 188 10 18.8 4137.148
Chain0.5in 0.75 1 0.75 4325.148
CoPoly0.625in 112 5 22.4 4325.898
Chain0.5in 0.5 1 0.5 4437.898
RubberCord35mm 30 2 15 4438.398
Chain0.5in 1.402 1 1.402 4468.398

20.7. Simulation run time and environmental conditions

Before running the model with waves turned on it is important to let the mooring reach steady state by applying a constant current. The settling simulations can take very long to settle when using a Cable DObject as the mooring is over 4 km in length and has far to travel to reach its settled position. For this reason the QuasiStaticCable is being used instead.

  • Set the $CurrentProfile property to 4 (linear shear current profile).
  • Right click on the property and select ‘Resolve Follower Properties’.
  • Set the $CurrentSpeed property to 0.3.

This current will be used to settle the mooring and leave the current heading at 0 deg.

Note

  • More information on current profiles can be found in the Current Profiles tutorial.

For the QuasiStaticCable, three timesteps will be simulated. The first timestep at 0 seconds is the starting position. The second timestep at 1 second is the mooring line settled in no current. The third timestep at 2 seconds is the mooring line settled in current. To accomplish this we must set the current properties to start at 1.0 seconds.

  • set the $EnvironmentTransitionMode property to 1.
  • Right click on the property and select ‘Resolve Follower Properties’.
  • Change $CurrentTransitionMode to 1 and resolve its follower properties and set the $CurrentStartTime to 1.0.
  • Ensure $WaveTransitionMode is set to 0.
  • In the simulation input file, change the $EndTime property to 2 seconds.
  • Set the $IntervalOutput to 1.

The cable will have reached its steady state configuration after a single time step.

  • Update the integrator feature to use $IntegratorType 0 with a time step of 1 seconds.

20.8. Run simulation to get steady state results

  • Click Run

Once the simulation is compete the entire mooring line will have reached its steady state profile.

  • Open PostPDS to view the mooring line displaced by the constant current applied.

Use Engineering mode in PostPDS to easily locate the cable. Due to it’s length and distance from the simulation origin, it may be difficult to see in Rendered mode.

20.9. Convert QuasiStaticCable to Cable

The final state of the mooring can now be exported into a new project that will convert the QuasiStaticCable into a Cable DObject.

  • Export the final state of the simulation to a new project.
  • Open the new project in PST.
  • Convert the QuasiStaticCable DObject to a Cable DObject.
  • Update the Simulation properties such that the output interval is 0.1 seconds and the simulation will end after 30 seconds.
  • Set $IntegratorType 1 in the integrator feature and resolve its follower properties.

The default integrator properties can be used.

Note

  • Reminder that follower properties can be automatically resolved by pressing Ctrl-R when the cursor is on the master property.

20.10. Apply dynamic wave loading

Once steady state is reached the environmental conditions can be changed to any desired testing conditions More information regarding environmental conditions can be found in the Wave models and Wind models tutorials.

  • Enable an AIRY wave with a height of 4m and a period of 9 seconds.
  • Run the simulation.
  • Once the simulation has completed, open PostPDS and view the mooring in waves.

20.11. Data sheets

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Fig. 20.4 Acoustic release data sheet

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Fig. 20.5 Glass floats data sheet

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Fig. 20.6 Data sheet for 30” and 37” steel float

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Fig. 20.7 WaveRider data sheet

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Fig. 20.8 Shackle data sheet

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Fig. 20.9 Swivel data sheet

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Fig. 20.10 Yale Cordage data sheet

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Fig. 20.11 Polypropylene data sheet

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Fig. 20.12 Rubber cord data sheet

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Fig. 20.13 Rubber cord specific gravity data sheet