This article will guide you on how to add a Crew transfer vessel (CTV) to your case. There are two steps to adding a CTV:


1. Open your case and go to  BuildLogistics+Add

2. You will then have a selection of vessels that you can add. Click on Crew transfer vessel

3. When you select the vessel type you want to add you will be directed to the selection of that vessel in your input library. Just click on the instance you want to add.

4. Complete the necessary information on how the vessel should be used. In this case, the number of vessels you will need, the home port, etc.

Construction Design 

O&M Design 

  • Name: The name of the Vessel
  • Number of units to add: How many CTVs you will add
  • Dedicated Task (O&M only): You click this when you need a CTV to support an HLV  for a corrective task. If you click this it means this CTV will only do the task with the HLV and nothing else e.g inspection, preparation, and finalisation.
  • Port: it is mandatory to add the port. If you have not added a port to your case yet, you will not be able to add the vessel.
  • Mother vessel: in the case that you will use an SOV, you can assign the CTV to the SOV in this section.
  • Spot chartered: enable lead time for vessel
  • Shift Start/end time: The daily availably of the vessel 
  • Alter vessels settings: Here you can define if the shift time is constant or if it alters. 
    • by date and the settings will repeat annually: This option lets you assign the vessel to only be available within the period you have selected. In the example below, the vessel will be available from January 1st to April 5th each year.
    • periodically and specify durations by number of days: This option lets you assign the number of the days the vessel will be available, at which point, it will be unavailable in the same number of days. In the example below, the vessel will work for 14 days, then have 14 days off, before it starts it's rotation again for 14 days. 
    • by date and year (ConDesign only): This option lets you assign the vessels availability by both date and year. In the example below, the vessel will be available in 2021 from the 1st of August to the 11th of November, and in 2023 from the 5th of March to the 28th of July. 

  5. Click on 'Next' 


1. Go to your CTV and hover your mouse over it and click on it.

2. Add or edit all necessary information. Sections available are:

3. See more detail on each section: 


If you click on 'Crew transfer vessel 1' you will be able to make adjustments to the information you added when inserting the vessel. This is the shift, mother port etc.


  • Charter Length: is the availability of this vessel
  • Countries: For reference only. This field has no impact on your simulation.
  • Crew size (O&M only): Number of crew required to sail the vessel (captain, machinists etc). Not required for running a simulation.
  • Sites: For reference only. This field has no impact on your simulation.
  • Remarks: Optional remarks, for reference only. This field has no impact on your simulation.

Technician Capacity: the number of seats available on the vessel for technicians.


Cruising Speed: The speed of the vessel
Reliability: Currently not included when running the simulation, as it is only a visual representation.

Weather Criteria

  • Significant wave height access limit: The maximum height that the vessel can travel in on its way to the wind farm/substation
    • Add Matrix: Here you can define your weather matrix. If you chose this option you do not need to complete 'significant wave height access limit'
  • Wind speed access limit: Maximum windspeed for accessing a turbine or substation.
  • Wind speed limitation reference height: Height at which speed is taken from the weather file to model the 
  • Lowest tide: Tide parameter for vessels to be operational 
Fuel Consumption


  • Fuel Unit: Here you can pick between litre or tonne
  • Fuel consumption in transit: The fuel consumption when the turbine is in transit 
  • Fuel consumption when pushing on the asset: The fuel consumption when the vessel is pushing an asset
  • Fuel consumption when idle offshore: The fuel consumption when the vessel is idle offshore

In this section, you can define the cost involved with the vessel. The available cost depends if it is an owned vessel or actual vessel (contracted). 

Step 1: is define the currency 

Step 2: Add any cost you want to report on. Some examples of the cost you can manage are: 

  • Day rate: days where the vessel can do tasks, so it is available in schedule and if there is spot chartered it also has to be past the lead time
  • Fuel cost: The cost is based on the fuel unit, so if the unit is set to litre, the fuel cost will be per litre; if the fuel unit is set to tonne, then the fuel cost will be per tonne.
    • The fuel cost is a combination of a lot of different registration that then, in the end, get the total fuel consumption and from that the fuel cost.
      • in push - for transfer vessel, while they are doing dropoff and pickup - registered from hours
      • regular transit - registered from distance travelled
      • idle - when they are moving to be idle offshore - registered from hours
  • Mobilisation Cost: it counts every time there is a mobilisation
  • Port Fee: It is calculated every time the vessel moves from the port to another destination

Data Time Series

You can also add a cost time series, so your cost differentiates by year. This is done by clicking on the Open Time Data Series button.

Set your year range starting with 1 and how many years you want to simulate and click  Update- the actual year is derived from the operational start year on the assets (if your operational start year is set to 2021-xx-xx, year 1 is 2021, year 2 is 2022 etc.), to which you can add the cost per year.

Activity Durations

Note: Define the unit (d/h/m/s). The example below shows that connection time is 5 minutes (5m)

  • Lead time: waiting time for the vessel to be available before taking any action on a failure. To activate it, go to the members tab and click on 'Sport chartered' or enable it when you are adding the vessel. The logic is explained below:
    • 1. A failure occurs and it is scheduled
    • 2. When scheduling the vessel, it will start a lead time of x days
    • 3. When on-site it mobilises and goes out to do work
    • 4. When back in port after the task/tasks is/are finished it becomes unavailable and we have to wait x days (lead time) for a vessel again when a new failure occurs. Failures that happen before work on the first failure is finished, will also be fixed.
      • Note: there will only be a lead time when there was no task already. So if a task is created on 1st January and three days lead time then it will first start on the 4th of January, but if another task is then created on the 4th of January then that one will not have a lead time, as the vessel is already called and on the site.
  • Connection time: Time needed for the vessel to connect
  • Disconnection time: Time needed for the vessel to disconnect
  • Personnel transfer time per technician: Time needed for the personnel the get on/off the asset from the vessel 
  • Equipment transfer time: Time needed for the vessel to let off equipment 
  • Mobilising time per port visit: The time needed for the vessel to mobilise. It happens every time they leave port. If they have an infinite shift, it will happen once a day.
  • Demobilising time per port visit: The time needed for the vessel to demobilise 

4. Click on 'SAVE' when done