3-54. LINE SHAFTING (PORT SIDE ONLY) - MAINTENANCE INSTRUCTIONS (Continued).
(5) Some boats are not structurally rigid and some carry their
load in such a way that they will "hog" or go out of normal
shape with every loading and unloading. Where this
condition exists, it may be necessary to make a compro-
mise between the top and bottom coupling clearance by
leaving a greater clearance at the bottom of the marine
gear output flange and propeller coupling. This clearance
might be 0.005 to 0.007 inch (0.013 to 0.018 cm) while the
top would maintain the standard 0.002 inch (0.005 cm).
(6) During the process of securing final alignment, it may be
necessary to shift the engine many times. When the final
alignment is secured, the necessary steel or hardwood
shims are made up and the engine and gear is fastened in
place. The alignment is then rechecked, and if satisfactory,
the coupling is bolted together.
(7) When a heavy boat is dry-docked, it naturally undergoes
some bending. Therefore, it is always good practice to
unbolt the marine gear coupling and prevent bending of the