Cardude close call on crossing

[healhustler]

As I speak here, our prolific TF Member, Cardude is limping in after nearly completing a rather uneventful two day (east to west) crossing of the Gulf of Mexico. About an hour or so from the targeted Pensacola Inlet, he felt a disturbing vibration in the usual drone of his faithful Island Packet 41 PY Cruiser.

Reportedly, he pulled back the throttle but the vibration was still there. Weather conditions and waves we’re going downhill in the recent hours of the trip, but he had to shut it down and check out whatever could be causing the vibration.

As it turns out, all but one of the bolts holding the shaft to the transmission had sheared off or were missing, a butt puckering sight in and of itself. He spent some time searching around in the bilge for the remains of whatever bolts there were, and during the search the boat was wallowing out of control and had turned abeam into the waves, making the effort even more difficult, finally culminating in poor Bill emptying his guts into the bilge. Nothing like being sick about your boat and the situation and barfing over your project at the same time.

Thankfully he found a few usable bolts in his on-board supply, enough to get the shaft back together and the boat underway again. So much for the uneventful crossing. Last message I got, he was still limping into Pensacola Inlet.

If that last bolt would have let go, it could have been a whole different situation. How often do you check your shaft bolts?

 

[psneeld]

Doesn't he have a sail rig?

 

[DavidM]

Shearing prop shaft bolts is more common than we think. It happened to me while helping a friend move his new to him trawler up the coast. The mechanic who replaced the bolts said it is a fairly common occurrence.

So check the tightness, preferably with a torque wrench, every year.

David

 

[Bmarler]

there's a lesson in there for all of us i guess. just add it to the ever growing list of things to check each season.
i carry a drogue to deploy off the bow to help keep me pointed into the wind if things go sideways. it won't work in all situations, but it's a good thing to have on hand. i'd much rather be pitching fore and aft than take it on the beam.
so glad to hear he made it across ok though.

 

[RT Firefly]

High strength bolts needed perhaps ?

 

[HTurner]

Doesn't he have a sail rig?

Yes, he does.

 

[Wayfarer]

Great, one more thing to be anxious about while I'm trying to enjoy my next trip, lol. Glad you made it in CD!

 

[kthoennes]

I don't think I've ever checked my shaft bolts. Boy that's got to be stressful, glad he came through okay. One more item for the list...

 

[Bmarler]

High strength bolts needed perhaps ?

good thought. with high strength you lose some ductility. what do the coupler manufacturers recommend?

 

[Max1]

Sorry, as a noob, which prop shaft bolts are we talking about? at the packing gland?

 

[Bmarler]

Sorry, as a noob, which prop shaft bolts are we talking about? at the packing gland?

coupler i assumed

 

[Max1]

coupler i assumed

Ah- The ones where the transmission joins to the shaft?

 

[healhustler]

Yeah, the coupler at the transmission. I have to admit, the only time I’ve ever checked my shaft bolts is when I did a seal change or pulled the shaft. Having to lay over the engine, it’s not that easy. After this incident and from what David added above, it goes on my list.

 

[Bmarler]

Ah- The ones where the transmission joins to the shaft?

exactly. there are many styles of couplers available, with differing methods of safely retaining the shaft. get to know what you have and what the manufacturer recommends for hardware and torque value.

 

[angus99]

Geez! Glad the Dude’s OK.

Reminds me to get our couplers checked out. The traditional coupler bolts have never been a problem, but some PO added a bolt on each coupler that goes transversely through the collar and the shaft. I occasionally find them sheared off and laying in the bilge. I replace them but, even with Grade 8s, they shear over time.

 

[slowgoesit]

Glad he was able to make temporary repairs. Hope he gets the rest of the way in okay. The concern once he's tied up to the dock is whether the bolts that failed elongated the holes in either the transmission flange, the flange on the shaft, or both. Flange on the shaft is not a big deal if you can source the part, and there is enough room to slide the shaft (with the prop on it) aft enough to remove/replace the flange. The flange on the transmission may be another matter though. Hopefully it is removable without pulling the transmission. Once the flanges are out, if they haven't been warped out of shape, the holes can be filled in, and new holes milled/drilled, best to do both of them at the same time. Once again I'm glad he's almost in!

 

[AlanT]

I had that happen around 18 months into ownership of a new delivery. We were living aboard so the engine was being used almost every day. I was looking for the oil change valve when I noticed that at least one (memory is faulty it might have been one or two) bolts that were loose. No vibration and the other two were tight but when I checked were way off torque setting. I put everything back, torqued it up and added it to my checklist. It happened again but I caught it while they were still tight (but not to torque setting).

I them promptly forgot about it until reminded by this post. I will check my torques on my current boat next time I am on board.

Thanks to the OP for posting this!

~A

 

[Ski in NC]

Seen that happen a bunch of times. Coupler bolts shearing. Most common on boats with tight access to that area where the last tech could not (or did not) get enough purchase on the bolts/nuts to get enough torque on them. Can hear the muttering "good enough". A few years later, it was not "good enough".

Gotta put the hoodoo on those grade 8 bolts/nuts. Whatever it takes, wrench-wise.

 

[Portage_Bay]

Geez! Glad the Dude’s OK.



Reminds me to get our couplers checked out. The traditional coupler bolts have never been a problem, but some PO added a bolt on each coupler that goes transversely through the collar and the shaft. I occasionally find them sheared off and laying in the bilge. I replace them but, even with Grade 8s, they shear over time.

I would be concerned there is play between the shaft and coupler. Key way or key worn maybe? Shaft too lose a fit in the coupler?

 

[healhustler]

I just checked mine and as I recalled it has a centering flange on the tranny side, so given such a situation as the Dude just went through, I probably wouldn’t have felt the vibration until the coupling came off the flange. A few turns whipping off the radius of the coupling while hanging onto a single bolt would surely take out my PSS seal and maybe my shaft log too. Geesh…I never had something give me the willies and heebee-jeebies at the same time.

 

[Shrew]

I'd be curious what the grade of the bolt is. There is a big difference between a Grade-2 bolt and a Grade-8 bolt.

Left = Grade 2
Middle = Grade 5
Right = Grade 8

 

[psneeld]

or worse...stainless....

 

[cardude01]

We made it to the dock with my temp repair. I need to go search for some good grade 8 bolts today. What about putting loctight on them?

I do have a sail rig, and the sails were up when this happened. If I was not able to fix the coupler that was my plan, but it would have taken forever to sail in, and I’m not sure I could have sailed through that inlet. We were about 70miles from Pensacola when it happened and it was pretty rough IMO.

A drogue would have been nice to keep the bow into the waves. 3-5’ swell and all that wind chop hitting the boat on the beam really sucked. It was too deep to anchor.

 

[psneeld]

proper torque with lock washers is the most important.

locktight I defer to more expert advice.

 

[Greg S]

If a grade 8 bolt is not tightened to it’s proper torque, it will shear easily. It has to be at it’s assigned torque to reach proper strength.
I’ve had several shear in a different application, and not under high load. As a result, I did some research. In my case a common bolt would have lasted longer but I require fine thread.
The correct post in this thread is the one where you were advised to find out what the flange manufacturer suggests.

 

[firehoser75]

I guess I think a bit differently. When I redid my PSS shaft seal a few years ago, I replaced all of the coupling bolts at the same time and installed lock washers as well. For the first year, I checked the nut tightness monthly. After that I checked them twice annually as they showed no signs of any loosening.
I guess I am more of a worry wart than some. Just a believer in preventative maintenance, I guess.

 

[healhustler]

proper torque with lock washers is the most important.

locktight I defer to more expert advice.

I agree with psneeld! I’m not an expert on Locktight either, but now that I know he’s safe, I’m almost sure it would work a lot better than Bill’s vomit.

 

[firehoser75]

Sorry, in my haste to post, I neglected to say that I am very happy to hear that Cardude made it safely back to port and that it appears no major damage was done!!
I am no expert on these things, especially the pros and cons of "locktite" in this case, but I am sure that vomit on the threads would not work.
Again, glad that Cardude made it safely back.

 

[Pack Mule]

I’m checking mine this weekend. Thanks for the post .

 

[diver dave]

In spite of that. Welcome to FLORIDA.

My only comment. IF the bolt doesn't see much length to stretch, just relying on torque alone may be risky. LW and blue locktite for me.

Consider a connecting rod assembly. Typically, no locktite or LW on those, just a correctly torqued nut, and look what horrific action it is subjected to. But, its on a long, stretched bolt.