Underwater connection installation

An underwater connection installation for connecting a riser to a flexible pipe for carrying fluids, said installation comprising:

• a post and a float for holding said post below a surface of the water, said post having a base suspending said riser and a top portion above said base:
• a pipe comprising an inlet end secured to said base of said post and a free outlet end which extends into said top post portion;
• a first coupling terminating said free outlet end, said first coupling comprising a first centering lip;
• a coupling endpiece mounted at an end of said flexible pipe, said coupling endpiece comprising a second coupling including a second centering lip, said coupling endpiece and said post including respective mechanical guidance devices shaped for coaxially guiding said first and second couplings and supporting said first and second centering lips in contact with one another when said coupling endpiece and said free outlet end of said pipe are driven toward one another;
• said mechanical guidance devices comprise matching frustoconical rings, one of said rings is mounted on said top post portion, around said free outlet end, so that respective axes of said one of said rings and said first coupling are substantially parallel, and the other of said rings is installed on said coupling endpiece coaxially with said second coupling;
• such that driving of said coupling endpiece and of said outlet end toward each other causes engagement of said matching frustoconical rings in one another and causes coaxial alignment of said first and second couplings, while contact of said first and second lips causes self-centering of said couplings.