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Installjac
Program version 8.1
10-June-2010
5
Launching a Jacket
5.1
Why
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The third task simulates the behavior of the structures as the jacket slides off the barge.
The main thing that we learn from this task is how stable the structures are during the
launch. We are verifying that we won't sink the barge. We are making sure that the
jacket will slide off the barge, not roll off the side of the barge, stop sliding, lift off the
barge, etc.
5.2
When
Run this task after verifying that the barge and jacket combination are in a suitable
launch position. Remember:
•
The velocities and accelerations of both structures must be zero.
•
Seventy to eighty percent of the barge should be in the water.
•
The barge should have a pitch between 2 and 2.5 degrees with the
stern lower than the bow.
•
The barge should have no roll or yaw.
Repeat the Data and Positioning runs until your structures satisfy these conditions.
5.3
Task Outline
During this task you will:
•
Enter the job option data using JOB, OPTIONS, and RESTART
cards. You will also set some time step and print options.
When you execute the program, it:
1. Starts at the equilibrium position calculated in the Positioning run.
2. Connects and activates the winch (or jack).
The winch will begin pushing the jacket down the launch tracks causing relative movement between the two structures. The movement of the jacket is
defined by the displacement of the jacket RPA from the barge RPA. The
movement of the barge is defined by the displacement of the barge RPA
from the origin of the FRA.
At this point, the jacket has been launched and is separated from the barge. You can
continue to analyze the actions of both structures, but usually you will want to study
only the jacket behavior.