What is a hammock and when to consider using?

This is not an article about a new way to stay productive and get rest at the same time! This is about how to use MS Project for tasks where the duration is dependent on other tasks.

A few user stories that spring to mind for where “hammocking” might help:

• Showing the time, the PM is assigned to the project based on how long the project is set to run.
• Continual testing throughout a delivery.
• Having access to a resource/site for the period of ongoing work.

When there is a task where the duration is dependent on other tasks, then you might consider to “hammock”. When a task is “hammocked”, it’s time is recalculated automatically when the linked tasks change their dates.

Want to try a hammock?

The magic of the hammock comes from using “Paste Special” and “Paste Link”.

Its relatively straight forward! Identify the dependant tasks and copy the start/end date you want your hammock task to run alongside. Copy the date and using “paste special” and “paste link”, paste the date into the relevant field of the task. This is now a hammock task! When the linked task’s dates change, the hammocked task duration and “linked” dates will change.

Here comes a bit of warning! Once you have hammocked the task date, you will see a little marker in the bottom right of the date box. This is the only sign the task is hammocked. So, you will need to make sure that in your plan, you can clearly find hammocked tasks, and the tasks the dates are linked to.

You’ll also notice that the duration days of the hammock task has the “?”. I always think of durations with a “?” as being estimates. I see hammock tasks as always being estimates, as the duration is dependent on other work. If you are not a fan of the “?” appearing in your plans, it can be changed e.g., if its “5day?” in the duration, just overtype with “5”. “?” removed but there are pitfalls if you make a mistake, and it can cause problems – which leads nicely on to…

What I have found with hammock tasks

A quick internet search for hammock tasks, shows there are different opinions around using them. So, please have a read round. I really like that it adjusts and aligns automatically but there are some cons to using it:

• It adjusts automatically – if you use a MS plan to work out costs or monitor budgets, be aware a change somewhere could add/remove days for the hammock task.
• It is not very visible – there is only the little marker in the date box and no sign of where it links to. I add the details into the notes. Also, make it clear in the task description and/or format the text so it is easily identifiable.
• Its schedule not resource – hammock tasks are about the schedule and the time not resources. Revisit them each time a date changes, to make sure you have got the resource for the full duration of the hammock task.

Is a hammock right for you?

It really does depend on what you are looking to achieve and how you use your project plans! What I would say is try it and see if it works for you!