Abstract
Marine operations are heavily influenced by the weather conditions onsite, be it the sea state or other adverse climatic conditions. When the operational limits are breached the works stop and the installation waits for the weather conditions to improve, this is known as weather downtime (WDT). During project preparation, it is essential to accurately quantify the expected downtime when calculating the project budget and schedule. For contractors, the expected WDT is a key input during tender phase of marine installation projects. It determines the most efficient scenario, the project schedule and the choice of equipment, and hence it has a significant impact on the overall budget estimation.
Various methods exist to assess WDT, which differ in the level of detail and complexity that can be considered. The most detailed method is the ‘simulation based on hindcast timeseries’ approach. This paper discusses the in-house developed tool CycleSim, which is one example of a WDT simulation tool. Based on a few example cases, the capabilities of this tool will be demonstrated as well as its added value compared to other methods and tools.
The tool is not only capable of considering complex combinations of basic weather limits (e.g., wind, wave, and current conditions), but it can also deal with more special phenomena such as coupled activities, daylight restrictions, inhibited working periods and flexible waiting windows (i.e., waiting for the tidal current to get below a certain limit). It can not only deliver basic statistical information about the expected project duration for the total offshore installation, including uncertainties (percentiles), but it can also provide planning calendars for each activity of the installation. Finally, it can determine the total expected fuel consumption which can be used to estimate the expected emissions which makes it possible to compare installation methods and choose the most optimal one from a sustainability point of view.
