In order to set up the towing vessels' processes, you will have to edit the towing vessel (tug) by clicking on it, and then going to the Processes tab. This can either be done from the Input library, or directly in a case.


Underneath the transit times, you can set up the parameters for each process step the towing vessel does, including setting additional variations.

Input labelDescription
Duration OR SpeedThe duration of the task OR the speed the towing vessel can sail in the current process.
Required weather windowThe duration of the weather window for the weather criteria in the process step. This can be longer than the duration, just to make sure there is a long enough weather window to complete the step.
NOTE: if required weather window is BLANK (not 0), then it uses the duration of the step as weather window. If the required window is 0, the vessel will ignore the weather window.
Max. time to wait before startMaximum time that the vessel is allowed to be idle before it can start on the process step.

Example: Lets say step 1 = 10h and step 2 = 10h. Imagine there is 12h of good weather, 1h of bad weather and again 10h of good weather. In if the max time to wait is 0h => then the vessel will stay in port as it is not able to complete these two steps within their required window.

Now lets say that the max allowed between steps is 4h => Then the vessel is able to perform the steps. eg (10h, wait 2h, 10h). The vessel will sail to the site and wait between the steps at the location.

The 'Inherit task duration' means that the step inherits the same duration as the task it is working on.

Example: if the duration on a maintenance task which requires the Towing vessel is set to 8 hours, then the duration in the step below would take 8 hours.

The 'Flexible' tick means that the step can be split up, instead of working on the whole task at once. If the time exceeds the value input, the task will start over again.

Example 1: The task below has 2 hour duration, and starts at noon (12:00) - but the weather gets bad at 13:00, and good again at 15:00 (2 hours with bad weather).

This task would then be worked on from 12:00 to 13:00, stopped until 15:00 and worked on from 15:00 to 16:00, at which point the task is completed.

Example 2: The task below has 2 hour duration, and starts at noon (12:00), but the weather gets bad at 13:00, and good again at 19:00 (6 hours with bad weather).

Since the max wait is more than 5 hours, then the duration will be reset back to 2 hours, and the task would be completed at 21:00 (19:00 to 21:00).

Weather Criteria

Under each step, you can set any weather criteria you need. The default setup is to only show

  • Wind speed
    Wind speed ref. height
    Significant wave height

but you can add or remove weather by clicking the three buttons in the top right corner of the step, and then the Manage limitations button

If there are unavailable weather criteria, as seen in the example above, it means that this weather data is not found in the weather files used in the current case.

You can set up the weather matrix on the weather criteria by clicking on the calculator icon - please see the Weather matrix article to read more about how the weather matrix works.

Input labelDescription
Significant wave heightThe maximum wave height that the vessel can sail in.
Wind speedMaximum wind speed allowed that the vessel can sail in.
Wind speed ref. heightReference height for the wind speed. You can add the reference height the weather restriction corresponds to in order to extrapolate the wind speed to the same reference height as the weather limitation.
Minimum tideTide restriction for the vessel to be operational.
Minimum visibilityMinimum visibility in kilometers required for the vessel to sail.
Swell wave height
Max swell wave height the vessel can sail in.
Zero up crossing periodMax zero up crossing period the vessel can sail in.
Current speedMax current speed the vessel can sail in.
Limited by daylightDaylight is automatically calculated based on the location.
Limited by lightningIf you have lightning data in your weather file, you can enable the lightning limitation.


You can assign different variations to specific maintenance tasks - if a task is not assigned to a variation, the default values are used.

You must first click on 'Add variation'

Give the variation a name

When in a variation, you get the option of assigning the variation to specific maintenance task(s) - you may select as many tasks to the variation as you please

NOTE: Once you've set a maintenance task to a variation, that task will not be selectable in the dropdown on other variations inside the same step. You may add a variation to step 2 and assign the same maintenance task to this variation.

Adding, removing and moving steps

In all the main steps, including any variations, you can add as many steps as you want, each with their own durations and weather criteria - this is done by clicking on the '+ Add step' button above, between or below the step(s).

You can remove a step by clicking in the three dots on the right hand side, and then clicking 'Delete'.

You can also rename all the steps, and move them up and down after they have been created.

If you want to have the same weather options on all variations, you can bulk mange all the weather selector for all variations in the same step - this is done by clicking on the three buttons next to the main process, and click "Bulk manage limitations".

The same settings can be changed for all steps in specific variations.