The Perfect Shaft Alignement

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Jun 7, 2004
31
Hunter 310 Herrington Harbour South, MD
Last summer I had realized that I had to do something about the shaft vibration but I wanted to do the perfect alignment, not just bring the coupling flanges to within acceptable tolerances. So I devised this new method and replayed it over and over in my head until the boat got hauled last October and got a chance to practice my concept while high and dry. This method requires that the cutless bearing be replaced at the same time. You will need: a)new cutless bearing and removal tool, b)video camera with long cable and a portable TV, c) A lot of time and patience. Here is the procedure- 1-Disconnect and separate the output and shaft couplings. 2-Remove the prop and cutless bearing. (Use the proper tools-banging won't work). 3-Back the packing nut off and remove the stuffing material.(It's better if you also remove the flex hose from the log tube so you can center the shaft through the tube as well). 4-Place the video camera on a tripod between the rudder and the end of the shaft so that the camera is looking straight down the axis of the shaft as it passes through the strut. Connect the camera to the monitor inside the boat by the stuffing box where you will be working. 5-Clean the contact areas of the couplings and use emery cloth if necessary to make perfectly smooth. 6-Tighten the couplings together as tight as you can and use locktide if the nuts have a history of coming loose. (I replaced my bolts and nuts with new). 7-Loosen the nuts on the engine mounts and adjust until the shaft passes through the center of the strut and without coming in contact with the strut walls. You can monitor this on the TV next to you with the camera you have set up outside. When you think you have it right, rotate the shaft by 90degrees and adjust again. Rotate and check again. This is the most critical part so spend as much time as you can here. Tighten the nuts on the mounts and grab the engine and shake it a hard as you can(simulate operation) and check alignment again. When you think you got it right, tighten the nuts on the engine mounts. Note that there is zero gap between the flanges and the shaft is perfectly centered through the log and strut. 8-Install the cutless bearing and prop. Install the packing nut. You can loosen the flanges and check alignement after launch if you want to know if the hull shape has changed. Since I had no vibration, I didn't do that. I did this a few months ago but did not want to post this until I actually launched the boat and verified my theory. The vibration almost disappeared at all RPMs. Note: I was planning to replace the cutless bearing and install a dripless shaft seal anyway. I think that even with the possible hull change (in theory)when put in the water, this is the best method especially when considering the alternative. P.S. I posted this message back in 2002, and I'm reposting to see if anyonoe has tried it since then. S/V Calaloo
 
E

ed

you better check it with a gage

fun idea and probably in straight but after launch check the cupling with a feeler gage. the boat will change when yo set it in the water! and it can wear out a cutlas quick. by the time you find it its too late.
 

Alan

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Jun 2, 2004
4,174
Hunter 35.5 LI, NY
Agree with ed

You've gone through a lot of pain staking efford for what will wind up to be an inaccurat measurment. Of course the hull changes shape out of water. The resultant shape and therefore adjustments would be fine if you kept the boat on the hard, but when it gets back in the water everything changes. I'll give you an 'A' for effort, but a failing grade for practice.
 
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