Aft strut realignment

[pbsurf]

I couldn’t turn the port propeller by hand after the aft strut cutlass bearing was replaced a year ago. Beginning this year I wrapped a line and stalled the engine out. While cutting the line away, come to find out I still couldn’t spin the prop by hand. Bearing had over 150 hrs. on. Hauled out, Had shaft trued and new intermediate cutlass bearing installed. Eyeballing thru the aft strut all the way to coupler looked like aft strut was up/down out ¼”. Last week hauled out, dropped the strut. After a new cutless bearing was installed, the spin of the shaft was easier. A gap of ⅛” at the forward edge of the strut moved the bearing aft 3/16”. A tape dam was made, thickened epoxy was injected. Several spins of prop verified improved alignment. Drew up the last ¼” of the 6” x ½” bolts 18 hrs. later. Ride has improved.

 

[Lepke]

Alignment by eye was a very bad idea. You probably caused some extra transmission wear if not damage. Usually the rear bearing and sometimes internal splines.
If you don't have modern instruments, the old way is to run a stainless steel wire from the center of the trans coupling to the back of the after most cutlass bearing. You bold a plate to the transmission flange with a tiny hole in the exact center the wire goes thru. The same for the cutlass bearing. Get the wire as tight as possible. Then buy a good digital caliper and measure the distances from the wire to the various bearings. Moving the engine and struts as necessary. Double check everything. After the shaft is in, using a feeler gauge, check the transmission coupler by moving the gauge around the gap between the flanges. I get my shafts within .002".

 

[pbsurf]

Coupler to shaft alignment was checked, engine adjusted, engine run, and checked again all while in the water before aft strut project was started. I followed up the eyeball assessment by using the center of the transmission coupler and pulling a string line taut thru to a projected inline point near the rudder. The string was proof the misalignment was an up/down aft strut. However, I saw it with my eye first. While planning this project, I chose leaving the shaft (months earlier trued to eliminate .011" of wobble) in the strut and finding where the strut had less friction turning the shaft. First fit was not satisfying, better, but not much. Replacing the 193 hr. aft cutless bearing made a considerable difference in reducing friction. Before splashing, roll out (dial indicating guage) measurements were made. Between the intermediate and aft cutless bearing was .001". Next to the shaft was .000". A surveyor, David Pascoe, wrote a dial indicating guages for checking shaft alignment isn't valid because each new measurement location isn't referenced to the previous measurement setup like a calibrated roll bed for truing shafts. Plus there is there issue of on the hard and possible torquing of boat shape to effect alignment. IMHO is that if the measurements indicate a problem, there is one. If not, there may not. Down to can't turn my prop by hand is a problem, able to turn prop by hand is not. I feel good about where it's at and time will tell if it lasts.