The Society of Naval Architects and Marine Engineers released a 60-page technical bulletin Practices and Procedures for the Alignment of Marine Main Propulsion Shafting Systems. The bulletin was compiled by the Propulsion Shafting Panel, Panel M-16, of the Society's Technical and Research Program. While industrial machinery is typically aligned so that the shafts of the driving and driven machines are collinear, this approach is not appropriate for marine main propulsion shafting because the bearings move as conditions change, and because the shafting is never really straight as it deflects under its own weight and the weight of the propeller and other attached components.
