Abstract: A probe positioner for placing a monitoring device into the confines of a boiler or steam generator vessel. The apparatus includes a support arm having a plurality of links and hinges pivotally connecting the links. A handle is attached to a flange connected to the first link to provide axial rotation between first and second support arm orientations. A monitor mount for mounting monitoring devices is attached to the end of the third link opposite from the second link. The support arm is adapted to remain in the first support arm orientation while being horizontally placed through an opening in an inner and outer substantially vertically oriented wall and pivot downwardly at each hinge along the inner wall as the support arm is rotated from the first support arm orientation to the second support arm orientation without fully horizontally extending past the second wall.