FIELD: construction of sea drilling platforms. SUBSTANCE: semi-submerged ship has two or several submersible pontoons divided into compartments having form with opening or open section for embracing the bearing support on which deck of drilling platform is to be mounted. Ship is provided with ballasting units which consists of separate tight compartments in pontoons and control facilities for selective separate tight compartments in pontoons and control facilities for selective adjustment of flow of water fed to tight compartments. Deck of sea drilling platform is transported in slightly raised position on board semi-submerged ship and closes the above-mentioned open section in such way that immediately after proper positioning of semi-submerged ship, she is quickly ballasted bringing the platform to bearing base (i.e. slightly raised platform is positioned above bearing base after levelling relative to it). EFFECT: possibility of mounting the deck on various bearing bases at proper levelling and avoidance of damage to deck. 12 cl, 8 dwg
