Hull and Outfitting

Seakeeping - RMS Output

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Seakeeping - RMS Output

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Last UpdatedDec 18, 2025
4 minute read

RMS tables are produced for the six degrees-of-freedom motions, and for any additional calculations requested on the Seakeeping - Additional Calculations page.

In addition to these tables, graphical output of the RMS's is also available:

RMS Graphs

This displays cartesian graphs of the vessel RMS's against wave heading. All of the vessel speeds may be displayed on a single graph:

RMS	Choose a single RMS value to plot. The drop-down list contains each motion and velocities, added resistance, dynamic loads and motions at locations of interest if previously set up on the Seakeeping - Additional Calculations page.
Speeds	Check each speed required on the graph from the list in the drop-down check list.

You may add and delete graphs as necessary and may change the order of the graphs in the report by using the Up and Down buttons.

Add	Adds a single graphs to the grid (and hence report).
Delete	The Delete button is enabled when you select a number of rows from the grid control (by clicking on the numbers in the left-hand column). Highlighted rows are then deleted by clicking on the button.
Up	The Up button is enabled when you select a number of rows from the grid control (by clicking on the numbers in the left-hand column). Highlighted rows are then moved up the grid by clicking on the button. Note: If the first row is selected, then the button is not enabled, since the rows cannot be moved. This is useful for re-ordering the graphs that appear in the report.
Down	The Down button is enabled when you select a number of rows from the grid control (by clicking on the numbers in the left-hand column). Highlighted rows are then moved down the grid by clicking on the button. Note: If the last row is selected, then the button is not enabled, since the rows cannot be moved. This is useful for re-ordering the graphs that appear in the report.

RMS Contours

This allows you to display contour plots of the RMS responses. Vessel speed is given radially and the wave heading is displayed tangentially.

RMS	Choose a single RMS value to plot. The drop-down list contains each motion and velocities, added resistance, dynamic loads and motions at locations of interest if previously set up on the Seakeeping - Additional Calculations page.
Criteria / Minimum	Minimum criteria for contour plot.
Criteria / Step	Criteria increment for contour plot.
Criteria / Maximum	Maximum criteria for contour plot.

You may add and delete contours as necessary and may change the order of the contours in the report by using the Up and Down buttons.

Add	Adds a single contour to the grid (and hence report).
Delete	The Delete button is enabled when you select a number of rows from the grid control (by clicking on the numbers in the left-hand column). Highlighted rows are then deleted by clicking on the button.
Up	The Up button is enabled when you select a number of rows from the grid control (by clicking on the numbers in the left-hand column). Highlighted rows are then moved up the grid by clicking on the button. Note: If the first row is selected, then the button is not enabled, since the rows cannot be moved. This is useful for re-ordering the contours that appear in the report.
Down	The Down button is enabled when you select a number of rows from the grid control (by clicking on the numbers in the left-hand column). Highlighted rows are then moved down the grid by clicking on the button. Note: If the last row is selected, then the button is not enabled, since the rows cannot be moved. This is useful for re-ordering the contours that appear in the report.

Polar Plots

Up to three vessel RMS's may be included on each Polar plot. For each desired motion, you should set the following information:.

RMS	Choose an RMS value to include on the polar diagram. The drop-down list contains each motion and velocities, added resistance, dynamic loads and motions at locations of interest if previously set up on the Seakeeping - Additional Calculations page.
Use	Minimum criteria for contour plot.
Criteria	Select the criteria for the desired motion.

You may add and delete polar plots as necessary and may change the order of the plots in the report by using the Up and Down buttons.

Add	Adds a single polar plot to the grid (and hence report).
Delete	The Delete button is enabled when you select a number of rows from the grid control (by clicking on the numbers in the left-hand column). Highlighted rows are then deleted by clicking on the button.
Up	The Up button is enabled when you select a number of rows from the grid control (by clicking on the numbers in the left-hand column). Highlighted rows are then moved up the grid by clicking on the button. Note: If the first row is selected, then the button is not enabled, since the rows cannot be moved. This is useful for re-ordering the polar plots that appear in the report.
Down	The Down button is enabled when you select a number of rows from the grid control (by clicking on the numbers in the left-hand column). Highlighted rows are then moved down the grid by clicking on the button. Note: If the last row is selected, then the button is not enabled, since the rows cannot be moved. This is useful for re-ordering the polar plots that appear in the report.

Hull and Outfitting

Seakeeping - RMS Output

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Seakeeping - RMS Output

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