Creating a Coaming

This task explains creation of a coaming on an opening using a free edge stiffener.
A "free edge'' is the end of a plate that is not limited by another object. This could be a deck that does not run the entire length of the ship, in which case the edge that is not limited by the hull is considered free edge. Or it could be openings in the deck, the edges of the openings being free edges. Web girders also have free edges. Stiffeners are often placed on these free edges to strengthen them. The image below shows a free edge stiffener placed on an opening in a deck.






1. With your document open click the Stiffener on Free Edge button to open the Stiffener on Free Edge dialog box.

If you select the plate on which you want to place the stiffener before you open the dialog box it will be pre-selected. You can change the selection by clicking in the Plate field and selecting a plate in the specifications tree, or in the viewer. As soon as a plate is selected the free edges in it highlight and can be selected. When you move your mouse pointer over an edge it changes color. The image below shows the free edge of an opening, and the free edges of the deck, highlighted in blue.

  2. CATEGORY: Select a category by clicking the down arrow in the Category field, in this case stiffener on free edge.
  3. NAME: The application can assign a name to the object you are creating using the object naming function if you check the Automatic checkbox. If you want to assign your own name then uncheck the box and enter a name.
  4. EDGE: This field displays the free edges that have been selected. You can select more than one edge, and view them in this field.

The Entire Limit checkbox allows you to place stiffeners along all joined free edges, if they were defined with a sketch.

In the deck opening shown above, the free edge has been defined using a sketch, and consists of a circle. If you select the Entire Limit checkbox the stiffener will be placed on the entire edge. If you uncheck the option, the stiffener will be placed only on the element you select. In the image below, the Entire Limit checkbox is selected, and the mouse pointer has been moved over the opening. The stiffener will place on the green portion only.

You should note the following behavior:

When the Entire Limit checkbox is not selected, stiffeners placed on all contiguous edges will be combined into one. Initially they will display separately in the specifications tree, but will be combined once you click the OK button. This will happen if they were defined using the same process. If in the same document you have free edges that were defined using a sketch, and others that were defined using a non-sketch method, then:

  • All stiffeners placed on contiguous free edges defined by a sketch will be combined into one.
  • All stiffeners placed on contiguous free edges defined by a non-sketch method (e.g. planes) will be combined into one.
  5. Click the button next to the Edge field to display the Elements List. You can use the list to delete or replace stiffeners that you have added. To replace, select the free edge, click the Replace button, then select the new free edge.
  6. LIMIT: By default stiffeners are placed from end to end of the free edge you selected. If you need to resize a stiffener then you have to define the limits. In the Limits field select Start and then select a starting limit. You can select a plane, plate, another stiffener or a surface. The stiffener will be limited as soon as you make your selection.

Use the same method to define the End.

  7. WEB ANGLE: By default the web of a stiffener is placed perpendicular to the plate. If you want to place it at an angle then enter the preferred angle in this field, or use the Up/Down arrows. This option is available for both face plate and free edge stiffener types.
  8. TRACE OFFSET: This option is only available for a stiffener with free edge, and is the distance from the edge that the stiffener is offset. The default is always 10 mm. You can adjust according to your needs. In the first image above you can see that the coaming has been offset from the edge.