The article discusses the stages of design and implementation of marine operations connected with the installation of the spans on the Crimean Bridge. Mathematical modeling methodology using the Anchored Structures software is described. Examples of previously executed projects using this software are presented. The stages, which consisted of the marine operation to install the spans for the Crimean Bridge, are given. The extreme external natural conditions under which it is necessary to ensure the safety of marine operations are described. The limitations that were taken into account at the design stage are listed. The arrangement of the positioning systems developed to perform various stages of the operation is described. The parameters of the positioning system elements obtained by mathematical modeling of the designed marine operations are presented. The implementation of marine operations for installing spans on the Crimean Bridge is described and the conclusion about the coincidence of the estimated parameters with the data obtained during field observations on the execution of marine operations is presented.