ERROR ESTIMATION OF WATER DISPLACEMENT WHEN COUNTING DRAFTS BY THE DRAFT-SURVEY METHOD

The article presents a study and error estimation associated with mass discrepancy of received and delivered cargo, which arise when they are measured by drafts (draft-survey method) and because of the differences in measurement conditions in the ports of loading and unloading due to the presence of wave disturbance during the draft measurement, using a clinometer to find the draft from one of the boards, due to instrumental errors in determining density of seawater, as well as analyzing other possible errors. Formulas for error estimation of drafts due to heaving and the use of the clinometer have been proposed. When calculating the draft errors arising due to the ship squat, it has been suggested to replace the ship speed with the current speed in traditional formulas. Two similar criteria have been substantiated, for the allowable mass discrepancy of cargo at the port of loading and at the port of discharge, calculated by the draft-survey method-strict and statistical. These criteria will allow the cargo receiver and the carrier to make an informed and agreed decision on the significance of the mass discrepancy. Studies have been conducted on the example of calculating the mass of grain loaded onto the bulk carrier Oslo Bulk 6 in the port of Le Havre and unloaded in the port of Riga. As a result, when analyzing a rigorous criterion of discrepancy was found to be admissible, and in relation to the statistical criterion, the task was set for further research - substantiation of its critical value.