Cutlass bearing bolts working loose

[iansan5653]

On my Caliber 28 the cutlass is a two part design, with a piece affixed to the boat and another piece that slides into and secures to that with two large bolts. Each bolt has one regular hex nut and one lock nut on top of that.

Here is a photo of my cutlass: https://photos.app.goo.gl/VRv7iwHitYQctUFa6

Recently while motoring I heard a new knocking noise on the hull. I dove to inspect and found that the whole cutlass was slightly loose. The part affixed to the hull was secure, but the two bolts holding the two pieces together had apparently loosened. The shaft in the cutlass was secure so it didn't look like a bearing problem.

I tightened the two bolts down and the knocking stopped so I figured the problem was solved. But about four hours of motoring later, it started again. I again tightened it, as hard as I could, figuring I had just not given it enough torque before.

Now I'm on another trip and there was no breeze yesterday so we motored for over 12 hours. It was fine almost all day and then the knocking began again.

I dove this morning and sure enough, I was able to tighten the nuts down significantly. I tightened even harder this time. As hard as I physically can.

The problem is again solved, for now. But I feel like there must be something other than simple lack of torque going on here. My alignment is good and my mounts are brand new.

I'm just looking for ideas for troubleshooting here. If you had this issue before, what was the culprit? Maybe the nuts are installed incorrectly? Is this a sign that the bearing is worn out, even though the shaft is snug in the cutlass? Does the whole cutlass fixture need to be replaced? Just trying to figure out what to look at next.

[Sun and Moon]

Originally Posted by iansan5653

...Each bolt has one regular hex nut and one lock nut on top of that.

Not sure why you would have a regular nut and a lock nut. Usually you have one of the following 3:

1) Two normal hex nuts. The first is tightened down to the desired torque, then it is held in place and the second is tightened against the first.

2) Normal nut with a split-washer (also called a lock washer).

3) A lock nut. Not sure I would trust a lock nut in this situation. I don't know how the nylon is going to behave underwater over time. Nylon does absorb water, leading to swelling and softening. Maybe it works, maybe it doesn't.

I would think that your setup with a regular nut and a lock nut would work as long as the regular nut is put on first and the two nuts are tightened against each other. But it's odd, and it's clearly not working.

[PippaB]

I would describe the part with which you are having problems as the P-bracket or prop strut rather than cutlass/cutless bearing, but that is somewhat beside the point.

Is this a new problem? Have you wrapped a line around the prop recently? I would suspect the most likely culprit as excessive vibration:

1. Misaligment - is the engine properly aligned? When was it last checked?
2. Bent parts - comes from the question above, a wrapped line could have bent the shaft or strut, leading to increased vibration.
3. Worn motor mounts - if the motor mounts are old and have gotten soft this could lead to excess vibration in the drive train. Or even broken, where one or more motor mount studs are no longer connected to their bases, and are held only by gravity.

[boatpoker]

Vibration is what causes nuts to come loose. It could be a motor mount / engine alignment issue.
I've never seen a 2-part P-strut before ... is that original or someones kludge job.

[iansan5653]

I think alignment must be the culprit. I did it after installing the new mounts but maybe I'm not very good at it.

Thanks for the advice. Knowing it's a P-Strut will help my research significantly.

[sck5]

Calibers have a P strut and the bolts sometimes vibrate loose. It has happened to me. Yes, you can tighten them back down and be OK for a while but you very likely put some serious wear on the cutlass bearing and will need to replace it in the near future. That is the time to also check out the packing gland, alignment, prop shaft,etc.

[sck5]

Additional note = in my case cutlass bearing wear is what seemed to have started the whole problem. Once it has some wear it vibrates, a little at first, and then a lot, loosening the bolts. I had to replace the cutlass bearing and tighten everything back up again after making sure te alignment was OK

[Bowdrie]

IIRC, back in the day when the OPs boat was built, both Wilcox-Crittenden and Buck Algonguin made "adjustable" P-brackets.
The upper section fastened to the hull, the lower section carried the Cutless bearing.
The angle between them was adjustable, secured with a couple of bronze bolts.

[mcswain29]

Originally Posted by boatpoker

Vibration is what causes nuts to come loose. It could be a motor mount / engine alignment issue.
I've never seen a 2-part P-strut before ... is that original or someones kludge job.

Buck Algonquin manufactures a few different types for retrofit/repair/custom applications. Wouldn't be my first choice but they do exist...