NOVELTY - The support arrangement has a socket defined by one socket wall. The socket has an engaging portion (5,7) with an engaging surface arranged to cooperate with an engaging surface of a male engaging mechanism. The engaging portion of the socket facilitates displacement relative to the socket wall upon a force acting on the engaging surface by the male engaging mechanism.    USE - Support arrangement for a securing turbine e.g. tidal stream turbine of a marine turbine system on the seabed.    ADVANTAGE - A low friction guide added to the male engaging portion reduces the risk of jamming or damage to the contacting components during installation. The guide is made of a material that provides adequately low levels of friction to allow smooth installation of the turbine to proceed unimpeded. The male and female engaging portions has features that allow the smooth installation and location from different angles, directions of fluid flow and varying weight of the turbine loading the system. Material of the leading portion has a friction coefficient lower than that of the material of the bearing portion to allow smooth installation of the turbine. The relative densities of air and water in conjunction with the constant vertical orientation of the male engaging portion to remove the requirement for watertight rotating sealing of the rotating electrical transmission increases the reliability and reduces the cost of the system. The male engaging portion can be easily adapted to incorporate a vertically oriented air chamber without requiring watertight rotating sealing. The combination of protrusions and bearings provide a seal between the rotating transmission unit and water level which reduces the chance of splashing water reaching the rotating transmission unit.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a machine turbine generator housing.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross sectional view of the internal of the connecting system for an energy transfer unit.    Receiving cone (4)    Engaging portions (5,7)    Transition piece (6)    Foundation structure (8)    Engaging components (9,10)