Abstract: The article presents the results of measurements of the slowly changing hydrodynamic pressure field HPF generated by the movement of the ship, Zodiak, in the Bay of Gdansk. The measurement results have been obtained in the framework of the program of the work in Siramis, under the auspices of the European Defence Administration of the EU, by the research team of the Naval Academy in Gdynia. The measurement results were compared with the results of the calculations using the boundary element method as distribution singularities on the vessel surface and at the bottom of the sea. Also used, in part, were HPF measurements carried out for the ships Kapitan Poinc and Quest, made by the same research team. The results of the measurements made it possible to verify the analytical model for calculating HPF. Then, calculations were made with HPF dimensionless characteristics depending on the ship's speed, the depth of the sea and the distance from the plane of symmetry of the ship.