That's what I'm thinking, also. If the shaft was aligned before and the key was added, this makes the most sense to me.. at least as a first thing to try. Its difficult to see, though. The mechanic says the shaft is worn.rcvesselstyn wrote: Wed Mar 09, 2022 6:34 pm Hi Mary just a thought. If your mechanic needed to rekey the shaft sometimes that can put it off center especially if the hub was worn. It did not appear from the video that the shaft is bent just that it's origin is off center. Just a little sketch that's extremely exaggerated to show what I mean. 20220309_181803.jpg if this is the case no amount of alignment can solve the problem. I would check the hub and the prop shaft first to make sure that that this isn't the problem before trying to make any adjustments to the position of the engine or v drive. If it is the problem it can be shimmed with a sleeve before you consider replacing the prop shaft.
Thanks Joe. I had the cutlass bearing replaced when I hauled out a year and a half ago. I fitted a new prop at the same time. The stuffing box has just been re-packed with gore tex. Thank you for the other suggestions. Changing the engine mounts sounds like a difficult project, and if the shaft was aligned before, wouldn't it be likely the engine is already in the correct position?Jedsail wrote: Thu Mar 10, 2022 10:27 am Concerning your prop shaft wobble - This needs to repaired, not just patched. You really need to haul the boat, and evaluate your drive train.
FIRST - replace the flexible engine mounts if they are collapsed or oil soaked. Otherwise, engine / shaft alignment cannot be accomplished.
If your mounts are older than 8 years or so, they are suspect.
Now remove the prop and shaft from the boat, rebuild the stuffing box with a new stern tube hose, T bolt clamps, and Gore Tex packing.
Measure for the new stainless steel shaft, [ ensure the "overhang dimension is within spec] and order a new coupler with it, to be "fit and faced". This will ensure the coupler and shaft rotate concentrically. Install a new cutless bearing. This is also a good time to have the prop checked for blade and hub bore condition.
Now check the prop hub bore to prop shaft taper, using Prussian blue. Lap it, if needed, so they fit correctly and the prop will rotate concentrically with the prop shaft. CORRECTLY test assemble the prop to the shaft, ensuring there is no key interference. If room allows, insert the shaft with attached prop into the boat, and mount the new coupler to the shaft. Now center the shaft in the stern tube [ we use cloth rags ] and proceed with engine / shaft alignment. Once complete, remove the rags, place the stuff box assembly onto the stern tube, tighten the clamps and packing nut [ hand tight on the nut ] and launch the boat. After 24 hours in the water, recheck alignment and install new coupler bolts. NOW you will have a correct, reliable, and long lived drive train ! Joe
Thanks, Allen. I need to pull it and take a look. I have rarely encountered a super easy fix on a sailboat, but I'm all for it!allen wrote: Mon Mar 14, 2022 9:07 pm Wow, I really thought I replied to this thread. Basically what you are seeing looks just like what my prop shaft looked like before I aligned it after I had the engine rebuilt. My engine is hard bolted to the boat so no engine mounts so it really wants to be right on.
One thing I will say in answer to your question of if it was good before, would it not be good now. What you want is for the space around the coupling to be less than .003 inches or less all the way around. Ideally you would want the two plates to line up exactly and touch all sides at once before you put the bolts in. One thing I found is that there are four ways to bolt those two things together and you might find that there is only one of the four where the alignment is correct. Super easy thing to test and if that is the problem, super easy fix.
