Method for building structures in water

A method of building structures in water, comprising the steps of:

• (a) introducing into the water a substantially rigid casing or assemblage of casing units, at least some of which are prefabricated, the casing or the said assemblage provided for molding a self-hardenable material to a desired shape while isolating it from the surrounding water;
• (b) introducing self-hardenable material, or a temporary substitute therefor, into the casing or the said assemblage;
• (c) while the self-hardenable material or said substitute is being introduced, controlling the buoyancy of the casing or of the said assemblage and thereby the depth to which the casing or the said assemblage is immersed in the water, so that the hydrostatic pressure exerted by the water on the casing or the said assemablage is opposed by the pressure exerted by the self-hardenable material or said substitute;
• (d) lowering the casing or said assemblage onto an underwater surface;
• and
• (e) where a substitute was introduced instead of the self-hardenable material, gradually replacing said substitute with self-hardenable material.