Studying the issue of calculations ambiguity at determining the amount of loaded cargo

Abstract

A unified algorithm for calculating the amount of loaded cargo is provided in the paper. The algorithm checks the vessel readiness to carry out survey work, on the basis of which further operations or the elimination of inconsistencies that have arisen, are proposed. Attention is paid in detail to the measurements carried out during the draft survey, necessary for calculating the average draft of the vessel. The error value is given as a percentage of the deadweight of the vessel, depending on the measured source. The necessary conditions for the issuance of a permit by a surveyor to carry out loading and unloading operations on a ship after checking the conformity of the results obtained with the declared data are defined in the paper. The “Bow-and-stern Sediment diagram” is investigated as a method intended for approximate, but at the same time fast, non-commercial calculation. It is proved that the calculation of the vessel displacement based on this diagram leads to a significant error resulting from a fundamental misunderstanding of the draft survey process and its purpose. The most common mistakes at using ship’s documents, as well as the formulas use, are discussed in the paper. The ways of reducing inaccuracies in calculations are determined. It’s substantiated in the paper that the use of the “average draft” and “river” formulas cannot be carried out for all types of vessels due to their possible specific design features, in particular, additional grades of deepening and the presence of hull bending. The specifics of the ship’s register documents are given. The values of errors are also analyzed if there are only register documents on the ship. It’s proved in the paper that the proposed unified algorithm for calculating the amount of loaded cargo is quite accurate compared to other methods considered.