[Goodnewsboy]

There are three steps to shaft alignment.

1. Center the shaft in the stern tube. Usually done with the coupling disconnected. The goal is to place the centerline of the shaft as close to the centerline of the stern tube/stern gland as possible. Concentricity is the goal.

2. Adjust the elevation and lateral position of the transmission output coupling flange by adjustment of engine and/or transmission mounts so that its centerline coincides with the shaft centerline and with coupling halves approximately matched for bolting together.

3. Bring the coupling halves together loosely and use a feeler gauge to check parallelism of the mating flange faces. (They must be clean.) Check in the vertical (12 o'clock and 6 o'clock positions) and in athwartship (9 o'clock and 3 o'clock) directions. Make additional adjustments (fine) to engine/transmission mounts as necessary. If significant adjustments are made, separate the flanges and repeat step 2 so that you don't disturb the position of the shaft centerline.

4. When flange faces are parallel within the limits specified by the engine maker, tighten all mounting bolts and check for parallel one more time. If problem found, repeat #3.

5. With all mountings secure and flanges parallel, install and tighten coupling bolts.

This is a lot of work and it should be done when the boat is in the water so that it will assume its normal hull shape. Otherwise you may get to do it again.

There is an option. You could get a flexible coupling and that will eliminate some of the really fussy work on the flange faces. You will still need to pay pretty close attention to the rest of it.