I have been working on replacing my prop shaft after I bent it by wrapping a sheet around it on the very last sail of the season last year. Actually, I am embarrassed to say it wasn’t even a sheet but rather a dock line because I was lazy and was sailing alone. When I sail alone I will often take my spring line with me so when I come in to my slip I can get off the boat with the spring line in hand. Well, while I was sailing and the engine was off, the line wrapped and needless to say I could not get the engine in gear. I had a “great” idea to try to put it in reverse to see if I could unwrap the line – forget about it. I did not think I would have done as much damage as I did because the shaft was not turning and suddenly come to a complete halt as the line jammed. I was wrong. There was enough torque to cause the 1″ shaft to bend ever so slightly and make my engine wobble and vibrate. So I thought it would be a good idea to remove and replace the shaft and cutlass bearing on board Valkyrie. I learned quite a bit and thought I would pass on some of my thoughts to those who may have to do the same thing some day.
My original thought was I would have to drop the rudder in order to get the shaft out. I was dreading that job and thought it would be much easier to pull the shaft into the boat. Obviously, a much better and easier way to complete the mission.
In order to remove the shaft and pull it into the boat I had to remove the coupler from the prop shaft by removing the two bolts that screw into the shaft at 90 degree angle. Once those were removed I was able to remove the key way. The shaft was now free from the coupler, however it was a tight fit and I had to remove the entire couple from the transmission by removing the four bolts shown.
I loosened the stuffing box nut and simply pulled the shaft into the boat, after of course the prop was removed which I needed a prop puller to accomplish.
I had researched how to get the cutlass bearing out and was told to press it out using a threaded rod with bolts and washers. I opted to cut it with a hack saw blade. It took about a half hour and I was very careful not to cut into the strut. Once I had a cut in the bearing it was easy to tap out. Remember there are two set screws (not shown) holding the bearing in place. The replacement bearing I needed was called the “blackfish” and was ordered through West Marine at a cost of about $45.00 (US). I did not realize, until I had the new bearing in my hand, how worn the old one was. The wear was significant.
I then had my shaft duplicated at the local machine shop at a cost of about US$250.00. I replaced the anode and repacked the stuffing box using Teflon packing.
Now the tough part – Aligning the engine with the prop shaft. The shaft was reinstalled and the prop was secured. Without attaching the coupler I could see the prop shaft did not align perfectly to the center of the transmission opening where the coupler attaches. When I installed the shaft to the coupler and the coupler to the transmission the shaft had an elliptical motion. This motion caused undue wear and stress, especially to the stuffing box. It also added unwanted vibration. I spent two days tweaking the engine mounts to MOVE THE ENGINE TO MEET THE SHAFT. I still have an extremely minor “wobble” that I can’t get rid of. I felt that this is the best I could do, and compared to other engines I looked at, mine was “true” enough. The most important thing I learned; the four bolts on the outside circumference of the large coupler ARE NOT ADJUSTMENT BOLTS. They are simply bolts attaching the two round couplers together with rubber bushings to dampen vibration. I had someone else look at the elliptical pattern I could not get rid of and they adjusted these bolts, only later to discover they are not to be touched. Bottom line, I had to go to my machinist again to have the unit put back together because I could not get all the bushings back in line. That cost me a day! One more point. I was checking my transmission fluid level and discovered my dip stick, which should be attached to the filler cap as one unit, separated and the metal dip stick fell into the transmission! Fortunately I was able to get it out, but I lucky to find it before it was ground into the gears and cause major problems with the transmission. Oh, by the way, replacement cost is (I hope you’re sitting down) $112.00 (US). I decided to either epoxy or solder mine back together! This is a brief overview and I could go into more detail, however I think it gives pretty good idea of the project.
Written by Bill Fleming