What is a Hammock task ?

this might also be a silly answer: the word defines itself - Hammock (with two ends), for me, it’s just like an indicator with a beginning and an end. It will depend on how you use it with regards to the specific program (software) you’re using.

Hammock is basically a net consisting of cloth or a network of twine or thin natural or synthetic rope which is stretched between two firm points such as trees or attached to a metal or wood structure.

In similar way in P3, hammock is one of the type of activity to monitor the beginning - to - end duartion of group of activities. Is is normally used for reporting durations of groups of important activities.

Hi,

Hammocks are also used to assign resouces to a group of activity having common set of resources.

Regards,

Ashraf

Hello,

For me hammock tasks are very important tasks for modelling the costs in function of time. Changing the duration of hammock task (effected by another tasks) can be a factor of changing the cost!

It is specially usefull in software with Monte Carlo simulation but not only then. So, in summarise, I would like to tell that for me hammock tasks are interested specially from dynamic point of view (PERT/MC), not static (CPM).

In usual, static schedules hammock tasks are for me very useful for modelling the duration of main machines work, (specially heavy machines, f.e. cranes or other more special equipment).

hi
Tom
from
Poland

P.S. In new P3 (in my PContractor) I dont’t see hammock tasks. I don’t understand some big changes of P3 (and Pertmaster 8 too).

Hammocks are a summary of another set of activities.

Hi
check this thread u will find lots of info about hammock activities

http://www.planningplanet.com/forum/forum_post.asp?fid=1&Cat=2&Top=34771

Regards

mangesh

Hammock is the summary of group of activities.

its predecessor is ss of first activty of the 1st activity of the group and sucessor is the ff of the last activity of the group.

the usage depens on how effecently u use in the way u use


cheers!
Sridhar

Hi,

As with all the other responses, you should understand now that a Hammock is in effect a summary of a set of activities, it can be placed anywhere within the project. However, what the previous correspondents have ommited to advise you is the physical construction of a hammock.

Firstly ensure that you have set the activity type as Hammock, then for the links, make sure the Predessor link on the hammock is your first activity within the selected chain of events. Make this predecessor a Start to Start link within the hammock. Then for the Successor, determine the final point in time for the overall duration of the sequence of selected activities, this is not necessarily the final logic linked item but the latest completion scheduled duration. This link is then set as Finish to Finish.
When scheduled the hammock will automatically produce a start and end date/time with a computed overall duration, this constantly varies during scheduling to reflect the true actual duration.

Note that if your selected string of hammocked activities is volatile, ie potentially change or overun original duration, then it is best, I find, to link ALL activities as SS and FF to the Hammock task.

Hope this clears it up for you.

Regards
Alan

Hi Alan,

What you have written is absolutely true, But will you please elaborate us, what do you mean by linking all activities as SS and FF to the Hammock Task.

Do you wanna say that we will freeze the hammock duration by putting a start constraint to the hammock task? Is this what you wanna say.

Then what about the program logic?

Cheers,

Raviraj

Hi Raviraj

Constraints are a no no on the hammock itself, you can of course put constraints on individual activities within the hammock.

SS and FF links are required in order for the hammock activity to calculate its own value, much as a summary bar does.

You can also place any link type on any activity within the hammock but the eariest starting activity is (WITHIN P3) always a SS link. The latest completion link is similarly always a FF link on the hammock.

To ensure that you get these the correct way round I find it easiest to set up the links from the actual hammock down to the individual activty rather from the individual activites back up to the hammock.

Hope this clears it up for you.

Regards

Alan

In short,

1. All predecessor relationships to a Hammock must be Start-to-Start (SS) with zero lag.

2. All successor relationships from a Hammock must be Finish-to-Finish (FF) with zero lag.

Any other relationships involving a Hammock will be ignored.

Good luck!

never change a WBS type-task into a Hammock task! (unsolicited advice)