PRJ: How to Build a Hammock Task

Summary

A "hammock" task is dependent on external dates for both its start and finish dates and, ultimately, its duration. The name, hammock task, is derived from the way a hammock's shape is determined by the distance between the points to which it is attached.


As scheduled dates in other tasks change, the duration and start and/or finish dates of the hammock task change as well. In other words, given three tasks A, B, and C, task B must start on some date from task A (date A) and task B must finish on some date from task C (date C). For an illustration of this task B, see Example 1.

Example 1--Hammock Task B


A
| C
|-----B-----|
The span of time between dates A and C dictate the available time to accomplish task B. As Date A changes, the start date for task B changes as well; If date C moves, task B must finish appropriately. The difference between dates A and C is the duration for task B. See example 2.

Example 2--Date A Late, Date C Early


A
| C
|--B--|

More Information

To build a hammock task between two other tasks in Microsoft Project 2007 and earlier versions, follow these steps:
  1. Create or determine three tasks that correspond to A, B, and C in the example above.
  2. Highlight the cell that contains date A (the date that will determine when task B starts).
  3. On the Edit menu, click Copy (Cell).
  4. Highlight the cell that contains the Start date for task B (the hammock task).
  5. On the Edit menu, click Paste Special, and click Paste Link.
  6. Highlight the cell that contains Date C (the date that will determine when task B finishes).
  7. On the Edit menu, click Copy (Cell).
  8. Click the cell that contains the Finish date for task B (the hammock task).
  9. Click Edit, click Paste Special, and click Paste Link.

To build a hammock task between two other tasks in Microsoft Project 2010, follow these steps:

  1. Create or determine three tasks that correspond to A, B, and C in the example above.
  2. Highlight the cell that containes date A (the date that will determine when task B starts).
  3. On the Task tab, click copy.
  4. Highlight the cell that contains the Start date for task B (the hammock task).
  5. On the Task tab, select the Paste drop-down, and then click Paste Special. Select Paste Link and then click OK.
  6. Highlight the cell that contains Date C (the date that will dtermine when task B finishes).
  7. On the Task tab, click Copy.
  8. Click the cell that contains the finish date for task B (the hammock task).
  9. On the Task tab, select the Paste drop-down, and then click Paste Special. Select Paste Link and then click OK.

NOTE: The Date format on the Options dialog box muc be set to show time as well as date, such as Wed. 1/28/09 12:33 PM, otherwise the linked task will use the beginning of the day specified instead of the beginning of the next day.

Notes and Cautions

  • Do not specify a predecessor for a hammock task. Only Paste Linked dates will determine start and finish. You may specify predecessors for the tasks from which dates are paste linked into the hammock task.
  • A negative duration (finish date is before start) is not allowed. Depending on the source of the dates, the hammock task may turn into a milestone (zero duration) or erroneously calculate duration before the finish date or after the start date.
  • An OLE update is different from a calculation. You may not see expected changes in the hammock task after calculating project. From the Edit menu, click Links to edit/update OLE links (Paste Links). Alternatively, press the F9 function key twice.
  • Because the hammock task relies on other tasks for start/finish information, anything that affects those other tasks (resource leveling, constraints) will ultimately affect the hammock tasks dates.
  • If the hammock task is a child to a summary task, it may inherit predecessor behavior from the summary task that may affect its duration and/or start and finish dates or create a circular relationship.
Properties

Article ID: 141733 - Last Review: Sep 19, 2011 - Revision: 1

Microsoft Project 2000 Standard Edition, Microsoft Project 98 Standard Edition, Microsoft Project 4.1 Standard Edition, Microsoft Project 3.0 Standard Edition, Microsoft Project 4.0 for Macintosh, Microsoft Office Project Professional 2007, Microsoft Office Project Professional 2003, Microsoft Office Project Standard 2007, Microsoft Office Project Standard 2003, Microsoft Project 2002 Standard Edition, Microsoft Project 2002 Professional Edition, Microsoft Project Professional 2010, Microsoft Project Server 2010, Microsoft Project Standard 2010

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