There are many ways in which ship operations can be optimised. One of them is by optimising the trim of the vessel to achieve minimum fuel consumption. However, getting accurate data needed for trim optimisation is not easy, while being essential its success. Read about how it is used by one of the largest shipping companyies here.
Why should you consider Trim Optimisation
The main purpose of the method used to acquire trim optimisation data, is to relate propulsion power to draft, speed and static trim of the vessel. The method offers draft optimisation as a byproduct, since fuel consumption can also be compared for various drafts in balast condition. The differences between individual trims can be small from the hydrodynamic point of view, which is why a precise method is necessary to produce reliable data. Model tests present the most reliable way of acquiring data, while CFD offers similar accuracy, for a fraction of the cost.
Trim optimisation data is acquired by performing self-propulsion simulations at different sailing conditions. The sailing conditions are selected based on the operational profile of the vessel, in order to minimise the cost of the study. The sets of sailing conditions are further refined during the study itself, as the calculated data sheds light on powering trends, showing where to focus more in order to achieve higher savings.
Optimising Trim in Waves
The simulations used for trim optimisation are typically performed in calm water conditions. It is generally accepted that otpimisatio trends present in calm water will be reflected in ocean waves conditions. It is however useful to check whether that is true for a few conditions where the savings exist, to verify that the savings will also be present in realistic predominant sea conditions which the ship encouters. Have a look at a study done for an Aframax vessel on this link, and a video showing the comparison.
Maneuvering Simulations Using the Overset Grid Technology in foam-extend.
CFD Validation and Grid Sensitivity Studies of Full Scale Ship Self Propulsion
Fully Automated Ship Resistance Prediction using the Naval Hydro Pack