Forecasting the volume of defect detection works on a river fleet vessel hull

Abstract

The issue of using the new Instruction for defect detection of hulls of vessels for river and mixed (riversea) navigation to predict the number of measurements of hull structures during the subsequent regular survey is discussed in the paper. The electronic version of the defect detection report tables provided for in the Instruction allowing the necessary calculations to be performed is taken into account. At the moment, defect detection of a ship hull is the examination, measurement and assessment of defects in each element of the ship's hull in order to establish method and volumes of repairs that ensure its reliable operation until the next regular survey under specified operating conditions. However, the application of the new Instruction will not allow us to measure every element of the ship's hull, but only those elements whose measurement is necessary. An algorithm for filling out the defect detection report tables in their electronic version is provided in the paper, and the need for a preliminary (calculation) stage of defect detection, which is essentially an analogue of the concept of the zero stage in ship repair, is substantiated. The preliminary stage of defect detection is based on a probabilistic approach to predicting the residual thicknesses of individual ship's hull elements using known wear rates and data from ship's hull defects detection performed previously. The results of calculations of a test example for a representative vessel, for which detailed information both on the hull constructions and on the results of measurements during the previous survey and repair is available, are presented. Using the test example, it is proven that introduction of the preliminary stage of defect detection process will reduce number of measurements of hull structures by 78 % compared to the traditional approach to performing the detection work. The necessity of development at the preliminary stage not only electronic table, but illustrating maps of measurements of the main hull structures, examples of which are given, is substantiated.