In the Stinger component, the topmost drop-down box, Type, allows you to choose a J-Lay stinger. The fundamental inputs associated with a J-Lay tower are the tower angle and the location of the tower hinge, which corresponds to the stinger origin. You define these using the Tower Properties dialog. The tower hinge need not necessarily lie on the firing line of the tower, as illustrated in the 'Jay-Lay Tower' figure below.
Support locations are defined in terms of lengths along the tower, coupled with an offset from the firing-line. Unlike the S-lay stinger definitions, there is no user input required to specify the location of a hitch point as it is assumed to coincide with the tower hinge. Rotation of the tower is achieved by changing the tower angle and all supports are aligned parallel to the tower.
To position supports on the tower, you click on the Support Locations button. The Support Locations – J-Lay dialog, as shown in the figure below, allows you to define the support locations and the type of support provided.
Support Locations - J-Lay
To add a new support, you select the required Support or Tensioner component and specify its location using the Support Distance and Firing Line Offset entries. The Support Distance is measured along the tower, and the Firing Line Offset is measured perpendicular to the tower. By default the Firing Line Offset is automatically calculated by PipeLay such that the associated support is centred about the firing line, or in other words the pipeline running through the support is automatically kept collinear with the firing line. However if this is not your intention then you can manually input your own offset value. When defining offset values it is worth remembering the ‘Support Locations’ sub article of the Support component, which states that the input support location corresponds to a point on the bottommost surface of the support.
There is another dialog available to you when you are defining a J-Lay stinger and that is the Connection Point – J-Lay dialog, as shown in the figure below.
Connection Point - J-Lay
This dialog allows you to define, on the Stinger component, a Vessel Connection Point for subsequent use on a Model component; and to define the connection point location relative to the J-Lay tower stinger origin. The normal way to position a Vessel Connection Point is on the Model component, where its location is defined in vessel co-ordinate axes. However, for a J-Lay tower, determining the location in this way can be tedious, because most information about a J-Lay tower is known in terms of the tower dimensions. The Connection Point – J-Lay dialog allows you to specify a vessel connection point in terms of a connection distance and offset relative to the J-Lay tower. You can also specify connection point restraints or boundary conditions in the various degrees of freedom in the same way as you would on the Model component.
When you add a vessel connection point in this way, the scenario is as follows:
•PipeLay automatically works out the location of the connection point in the required axes without requiring further intervention or prompting from you.