Propeller shaft friction

[S/V Ethan Grey]

Maybe I’m over thinking this, but here goes.

I had the boat hauled recently and changed out the cutless bearing with a new one. I decided to go with a new propeller and shaft, but I didn’t have it at the time so I reinstalled the old shaft and propeller. I then relaunched the boat. Today I finally got around to replacing the old shaft and propeller with the new one. The boat is in the water and the engine is removed. To remove the old shaft, I simply had a buddy dive under the boat and pull it out while I pushed the new one through right behind it. This went wonderfully until the new shaft met the new cutless bearing. The new shaft was getting hung up inside the bearing and ended up pushing it out. No big deal as we could tap the bearing back in. However, the shaft was really tight inside the bearing to the point where it was really hard to push the bearing into the shaft log and the propeller shaft through the bearing, if that makes sense. We fought with getting the shaft through the bearing, and finally got it through. However, now that the shaft is through and the new propeller on, it is pretty difficult to turn the propeller shaft by hand inside the boat. I realize the bearing is new and the shaft is new, so I did expect it to have more friction than before, but it seems almost too much. However, I can’t think of anything that would cause it to bind.

Long story to ask, how “tight” should the cutless bearing (blackfish) be on a new propeller shaft? Should it be rather tight? Should I be able to easily turn the propeller shaft by hand from inside the boat when it’s disconnected from the engine?

Sorry, totally new to this whole inboard motor thing and thanks in advance!
-david

[tjr818]

I am sorry David, but I do not know, however I might be able to let you know soon - maybe my new shaft should arrive next week and I will put in the new Blackfish cutless bearing this week.

[S/V Ethan Grey]

Thanks Tim.

Doing a quick internet search there are some instances of shaft bearings swelling, if they are inferior brands. Mine is a new Morse Blackfish as identified in the owners manual, so I assume it’s good quality.

Since the shaft is disconnected from the transmission, it isn’t an alignment problem.

[wikakaru]

To remove the old shaft, I simply had a buddy dive under the boat and pull it out while I pushed the new one through right behind it.

You, sir, have some serious cojones grande to replace the shaft that way.

I've had a cutless bearing swell like that before. It was a long time ago, but if I recall correctly, I just ran the engine until it eventually wore in. If you can move the shaft by hand, even though it is with some difficulty, the engine shouldn't have a problem overcoming the friction as long as the shaft is well lubricated for cooling. You might want to loosen the shaft seal to let extra water through at first, and keep an eye on the temperature of the bearing, assuming you can feel the part of the hull where the bearing is from inside the boat. If you're in Niceville, I assume you are at a dock (there aren't many moorings around there). You should be able to run the engine in gear in the slip to play with the shaft seal and monitor the cutless bearing temperature.

Smooth sailing,

Jim

[John Stone]

...To remove the old shaft, I simply had a buddy dive under the boat and pull it out while I pushed the new one through right behind it.

Wait, what?! Did I read that right?

[S/V Ethan Grey]

Replacing the propeller shaft while in the water may not have been the smartest thing. I was surprised at how easily it went. My diver friend pulled out the old shaft (I had the transmission coupler removed) and I inserted the new shaft (I had the propeller removed) right behind it. There was barely any water let into the boat. Within the last month I replaced the stuffing box packing material with GFO. That stuff is amazing. It’s packed so well that I can tighten the gland nut by hand to get it to seal completely. The hardest part was getting the shaft through the Blackfish (cutless bearing) as it was a really tight fit.

Another interesting thing I found out was how little water comes through the stuffing box with the packing gland completely removed. I’ve always wondered if it would come shooting out or just trickle in. It’s a manageable steady stream. I feel confident now that if I had to replace my packing material with the boat in the water, I could manage it so long as I had someone standing by on the manual bilge pump.

[tjr818]

David,
I am still waiting for the new shaft. The 3-5 day turnaround time from Propeller Depot is now in its14th day and it is still not here
I did take the old shaft up to the boat today and did a test fit. I rubbed a little hand soap on the old shaft and it just slide right in. As long as I kept the alignment straight the shaft was easy to turn by hand, snug no loseness, so I think it will be okay. How is yours doing?

[S/V Ethan Grey]

Tim,
I ordered a new Johnson Duramax Cutless Bearing and I will be pulling out the Morse Blackfish. Although the Morse is new, something isn’t right and I don’t know what it is at this point. Perhaps its a swollen bearing (seems unlikely but it does happen). Maybe it’s binding internally somehow, but I just don’t understand how that can happen. It’s basically a shaft through a bearing and both ends of the shaft are free, there just doesn’t seem to be anything to bind. So, I’m going to pull off the propeller and pull the Morse, and see what the issue is. My other thought is that the setscrews keeping the bushing were tightened too much, deforming the bearing, making it more oval than round. Since the boat is in the water, it is a real pain to diagnose.
-david

[gonesail]

i did a stuffing replacement on my boat while it was in the water. seriously .. only a few drops came in when I removed the old packing. the whole thing was done in a few minutes. i greased the threads when reinstalling the stuffing box nuts.

[S/V Ethan Grey]

I wanted to update this post now that I have the situation all sorted out. I've learned a lot in the process, mainly to always slow down, stop and think when things aren't working out well. Not that I didn't know that already, but many times I get in a rush especially when I am in uncomfortable situations.

I can affirm that the propeller shaft, when in neutral, should turn by hand without much straining effort even with a new Blackfish or Cutless Bearing. It won't be frictionless, but there shouldn't be much grunting along the way After spending the weekend diving on my boat and pulling the propeller and the Cutless Bearing, I could see my mistake. If you read my previous post, you'll see that I changed the propeller shaft while the boat was in the water. I did this with the engine removed, so I pushed the shaft from the inside of the boat, through the shaft log, and through the Cutless bearing. It appears that when I did this, the end of the shaft, probably the cutout for the propeller shaft key, snagged the lip of the cutless bearing and ripped up the rubber inside of the bearing. In fact, it ripped up quite a big chunk, which got lodged in the bearing as well. Since I was in a hurry to get the new shaft in place...remember the boat is in the water and I didn't want it to sink, I was willing to push with more effort than usual rather than pull the shaft back out to inspect what was binding. In other words, I forced it, even when it didn't feel right. I justified it to myself as just a tight bearing.

While I could have just ran with it, I knew it didn't seem right and didn't make sense that it should be so hard to turn the shaft. So, I borrowed my buddy's scuba gear and dove on the boat myself and took everything back apart. Lucky for me, I knew I could remove the cutless bearing since it was not fiberglassed in, it's only retained by two set screws. Once I got the propeller, anode and bearing removed, I installed a new bearing and put everything back. It now spins like it should and I'm very happy. In the end, I have learned how to pull the engine from my boat, reinstall the engine, change out the shaft log, repack the packing nut, replace the cutless bearing, pull a propeller, size a propeller (as I replaced my old one) and scuba dive. My least favorite was scuba diving as the bayou I'm in is amazingly dark and I actually can't see the propeller on my boat until I'm a foot away. Diving in dark, murky water of a Florida bayou is not one of my things.