Method for positioning and locking a rotatable vessel

A method for positioning a rotatable vessel, the method comprising:

• rotating providing a vessel around having an axis of rotation and a target block fixedly attached thereto;
• rotating the vessel to a first position, wherein the vessel is free to rotate away from the first position;
• in response to rotating the vessel to the first position, extending a protrusion into a mating engagement with the target block and locking the protrusion and target block together, wherein the protrusion is rotationally fixed to a slide plate and moveable linearly away from the slide plate, wherein the slide plate is rotationally adjustable and lockable between non-predefined rotational positions relative to a fixed base plate;
• in response to extending the protrusion into the mating engagement with the target block, rotating the vessel from the first position to a second position, simultaneously with the slide plate and relative to the fixed base plate;
• wherein the vessel is locked in the second position when the protrusion and the target block are locked together and the slide plate is locked to the base plate.