Downtime related to excessive vessel motion and/or mooring line forces caused by environmental conditions is an important parameter for designing new terminals and ports in addition to planning offshore operations such as dredging, structure installations, etc. The present paper addresses an advanced approach using artificial intelligence in order to estimate the downtime in a more realistic manner. This approach is compared with conventional methods used in the industry and is applied for a number of terminal projects presented in this paper.
Operations at marine terminals are generally protected by a breakwater. These breakwaters whether are rubble mound type or caissons are expensive as constructed in deep waters in 20 m or greater. The conventional downtime methods result generally in a higher value which subsequently requires a longer breakwater once the downtime criteria is exceeded. The advanced approach for estimating downtime helps to optimize the terminal/breakwater layout and subsequently save on the CAPEX.
This approach estimates the downtime for the long term environmental time series using an inhouse Matlab code/program developed using neural network. In order to estimate the downtime, a set of specialized studies are conducted first illustrating the breadth and depth of port engineering. First, the wave climate for a long term time years is established at the project site using Spectral Wave Model MIKE 21 SW. The wave conditions are then transformed to the breakwater leeside (terminal side) using Boussinesq wave model MIKE 21 BW. Dynamic mooring study for the vessels at terminal is carried out using the time domain mooring analysis software MIKE 21 MA. Finally, an inhouse developed Matlab program calculates the downtime for the metocean time series based on the dynamic vessel response of the large set of selected environmental combinations.
Up to the author’s knowledge, this is the first published work highlighting limitations of conventional methods and the importance of implementing advanced techniques. This leads to a new thinking of how terminals are to be designed in the future.