Monitoring and Plotting Trim and Sinkage Data

A ship advancing through water experiences sinkage and trim due to the hydrodynamic forces acting on the ship hull. A towing tank ship model free to sink and trim can experience an increase in resistance. You can create a graph of the trim and sinkage over time to extract the value of this design parameter of your ship from the simulation.

To analyze trim and sinkage of the ship hull:

  1. Create a report for the trim:
    1. Right-click the Reports node and select New > DFBI > 6-DOF Body Orientation.
    2. Rename 6-DOF Body Orientation 1 to Trim.
    3. In the Trim - Properties window:
      • Set Angle Report Option to Rotation Y Axis.
      • Activate Constrained Angle Range.
  2. Create a report for the sinkage:
    1. Right-click the Reports node and select New > DFBI > 6-DOF Body Translation.
    2. Rename 6-DOF Body Translation 1 to Sinkage.
    3. In the Sinkage - Properties window, set Direction to [0.0, 0.0, 1.0].


  3. Create a monitor and plot for trim and sinkage:
    1. Multi-select the Reports > Sinkage and Trim nodes.
    2. Right-click on any of the highlighted nodes and select Create Monitor and Plot from Report.
    3. In the pop-up window, click Single Plot.
    4. Rename Plots > Reports Plot as Motion Plot.
    5. Right-click the Plots > Motion Plot node and select Open.
  4. Save the simulation.

The setup is now complete and the simulation is ready to run.