Down Time Analysis

A Down Time Analysis (DTA) tool is available that will calculate the days waiting on weather based on historical weather data for any offshore operation. The Tool will use time trace weather data, the dynamic properties of the equipment and the planning of the operation to work out the weather risk.

The result of the analysis will be a very accurate prediction of the weather down time days for the planned operation. This tool can also be used to design the operation and to select the best equipment for the local environmental conditions.

The following diagram shows the general setup of this analysis tool:


Environmental Data

Input for this tool can be any type of historical time trace data. Typical data input that can be processed is:

Waveheight, Wave period, wind speed, direction, current, spectral wave data, etcetera…

A direct interface with the NDBC historical database is available to download the free published data from the internet. Have a look at the website via this link.

Sequential Data And Criteria

Part of the tool is a planning module which allows the definition of the work in terms of nominal duration and sequence definition of the tasks. With this tool also the start and stop criteria are defined and attached to each task.

Dynamic Response

Wave dynamic responses from any type of dynamic model can be used as input for this tool. Orca Offshore can build the dynamic model and generate the required data for this analysis. Examples are multi body Lift Dynamic Model, Transport model, Mooring model.

Time Trace Tool

The heart of the DTA is the time trace module. This module will load the three sets of data and will perform a Monte Carlo simulation to determine the probability distribution of the weather risk for each month of the year. Dependent on the amount of historical data this approach will assure a very high reliability of the results.


The output will be the waiting on weather days per task and for the overall schedule. The weather days can be defined on any statistical ttresshold, e.g. 50% 95% relaibility etv. The following diagram shows a typical Schedule including P95 task weather down days.