Cardude close call on crossing

[Northern Spy]

Couplings in industry use fitted or expansion bolts. You actually ream the holes to size and use a machined fitted bolt. Or the bolt expands with a collar into the coupling holes to essentially make a rigid unit to transmit torque.

Our crappy little marine couplings use the friction of the coupling halves and the clamping force from properly torqued bolts to hold it together. Suboptimal.

But, since they are slow turning, low torque, and (should be) inexpensive they generally work.

But if there is any slop in the coupling bolt holes, the bolts are undersized, or they are not adequately torqued to achieve a proper tension and clamping force, the bolts will eventually fail in shear.

There is a lot of room for improvement for recreational marine couplings, but no company or standard seems to feel the need to improve.

Grab a bunch of the "same size" bolts and measure their shoulder diameter with a micrometer or even a caliper. Amazing to see the variation.

Optimally the flange faces would have zero runout and the flanges would be clamped together and drilled. Bolts would be machined with a shoulder to a tight tolerance, and the coupling would be reamed to fit the bolts.

Really not a lot of work, and is standard fare for a millwright.

The problem with this is as the boat is worked on at an average yard, the flange is whacked with a hammer by a boat "mechanic", or the bolts are swapped out for some off the shelf, and all gains are lost.

While I often side with Voltaire that "perfect is the enemy of good" . But in this case of marine couplings, it is pretty easy to turn good into bad, or they really aren't good enough to begin with.

 

[psneeld]

I think the saving grace for marine couplings is the number of failures that are not directly related to poor tightening or type of bolts used is so low that like most thing that can be improved...but is there really a need?

 

[Northern Spy]

I think the saving grace for marine couplings is the number of failures that are not directly related to poor tightening or type of bolts used is so low that like most thing that can be improved...but is there really a need?

I don't disagree. Heck, for the amount of times they are actually disassembled on the average boat, they could be welded together. (Yes I have done that in industry as well to keep operations going.)

Just saying it doesn't take a lot of effort or money to make things significantly better.

There is limited upside for the companies to improve their product line in the recreational marine industry, outside of the visual and tactile things that the customer touches and uses. Most customers couldn't tell the difference of the structural or mechanical aspects that make up the inherent quality of a boat.

I could likely engineer and market a better coupling, and have thought about repurposing and customizing some smaller industrial couplings about 15 years ago, but no one would beat the proverbial path to my door.

The inventor of the SmartPlug was met with great resistance for what is arguably an incremental improvement.

We live in a society where incremental cost savings are valued more than incremental quality improvements.

Hopefully cardude will check the face to face alignment, source some decent quality bolts and nuts, torque them to spec, and check them periodically.

 

[cardude01]

Hopefully cardude will check the face to face alignment, source some decent quality bolts and nuts, torque them to spec, and check them periodically.

That’s the plan. We had to leave the boat in Pensacola the day after we landed to get back to Texas for Thanksgiving. Will gather up some parts and head back to the boat soon to try to put things back together correctly.

 

[psneeld]

I don't disagree. Heck, for the amount of times they are actually disassembled on the average boat, they could be welded together. (Yes I have done that in industry as well to keep operations going.)

Just saying it doesn't take a lot of effort or money to make things significantly better.

There is limited upside for the companies to improve their product line in the recreational marine industry, outside of the visual and tactile things that the customer touches and uses. Most customers couldn't tell the difference of the structural or mechanical aspects that make up the inherent quality of a boat.

I could likely engineer and market a better coupling, and have thought about repurposing and customizing some smaller industrial couplings about 15 years ago, but no one would beat the proverbial path to my door.

The inventor of the SmartPlug was met with great resistance for what is arguably an incremental improvement.

We live in a society where incremental cost savings are valued more than incremental quality improvements.

Hopefully cardude will check the face to face alignment, source some decent quality bolts and nuts, torque them to spec, and check them periodically.

I had a few heart to hearts with the regional sales manager for Sea Ray and asked why a company would use a plastic hinge prone to breaking on a million dollar boat.

His reply was every department wanted to upgrade here and there....but he said at a boat show where a customer would buy brand X for a thousand dollars less, marketing would never go for it....even a hinge only $15 dollars or so different. And this was a part that failed often, not like flange bolts.

Drove me nuts.

 

[cardude01]

Finally got back to the boat with some new bolts. When I removed the temporary bolts I had in there and pulled the shaft back a bit the shaft noticeably dropped some. Is that just from the weight of the shaft or do I have a big alignment problem? I can easily move the shaft up or down or side to side. There is no support bearing near the transmission. The closest support is the stern shaft tube with the packing gland.



Also, I brought some feeler gauges to try to measure if the shaft flange is out of alignment with the transmission, but I’m unsure how to do that. Do I bolt the flanges together but not super tight and check it that way?

 

[diver dave]

Droop is normal. Yes, on feeler gauges; what I do is use a tightened single bolt with a flat washer between the flanges. Then measure all 4 points.

 

[Greatlaker221]

On some flanges there is a circular Tongue on one and grove on the other. Fit them together but not quite all the way. Use the feeler gauges in 4 points and adjust the engine if needed.

 

[rgano]

After removing all bolts and with the flanges a bit apart, just squeeze the flanges together with the tongue and groove aligned - I used a set of channel locks. 12 and 6 o'clock poitions note the DIFFERENCES. Do same for 3 and 9 oclock positions. Rotate the shaft 90 degress and squeeze again before measuring, and again, you are looking for the DIFFERENCES, not the absolutes measures So you can determine if you have abent shaft. Once that is done, you can put the bolts back in and check the 12-3-6-9 o'clcok differences to see if the engine needs moving. This video

does about as good a job of explaining this and much more as anything I've seen. Post those differences and we'll tall you what you have.

 

[cardude01]

Thanks so much for all the info. I’m going to have to do more exact measuring at another time it appears because my back is killing me and I can’t bend over and stand on my head long enough to do that right now. [emoji30]

I checked the clearance on the shaft as good as I could, and while it’s not perfect I just bolted it up and torqued the bolts down so we can go on a short cruise tomorrow. Will do it again when my back is better.

The shaft to trans bolts are not super easy to get to on this boat!

 

[Miz Trom]

Rich:
That video is the best explanation of all the variables of shaft alignment I have ever seen, and I've had an expert mechanic try to explain it to me.

Bill:

So sorry to read that you have a creaky back; I can relate. I cannot imagine doing the repair you had to perform while abeam to the waves, with your back issue. Has your back recovered?

We once had one outboard die while underway, and had to replace a gas line filter, but now you've got me thinking about what we would do if both engines died during a Gulf crossing. Yes, we would need a drogue. Much to consider.

Are you having the boat pulled to check the strut and cutlass bearing? Your coupler issue made me wonder if perhaps something banged hard against your strut, and perhaps moved it, when she was in the Abacos yard during the hurricane.

Cheers,
Mrs. Trombley

 

[Jarrow Lily]

We have an Island Packet SP Cruiser. I replaced the Cutlass Bearing in the stern tube last year at haul out. Six years before I had removed the old fashioned Stern Gland and replaced it with an Orbitrade rubber stuffing box. Each time I checked and adjusted alignment.

My coupling bolts are checked, by me, at the start of each season. The OE bolts on our boat are UNF thread, HT steel and have nyloc nuts. I have NEVER found them loose.
I dont use a torque wrench either, but 60 years as a pro mechanic has given me the 'feel' for tightness.
My previous life as a semi pro motorcycle racer who prepared his own bikes meant I trusted my preparation. You dont want bits coming loose around the Isle of Man TT course!
The 5/8 diameter HT bolts used on the coupling are well strong enough to drive the boat with a large safety margin.
As long as they are tight........................

 

[cardude01]

Rich:
That video is the best explanation of all the variables of shaft alignment I have ever seen, and I've had an expert mechanic try to explain it to me.

Bill:

So sorry to read that you have a creaky back; I can relate. I cannot imagine doing the repair you had to perform while abeam to the waves, with your back issue. Has your back recovered?

We once had one outboard die while underway, and had to replace a gas line filter, but now you've got me thinking about what we would do if both engines died during a Gulf crossing. Yes, we would need a drogue. Much to consider.

Are you having the boat pulled to check the strut and cutlass bearing? Your coupler issue made me wonder if perhaps something banged hard against your strut, and perhaps moved it, when she was in the Abacos yard during the hurricane.

Cheers,
Mrs. Trombley

Back has recovered after about a week. Need to strengthen my core/back somehow.


I need to have the boat pulled soon for a bottom job and will check the cutlass bearing then. I don’t think anything has banged into the strut but not certain.

 

[cardude01]

We have an Island Packet SP Cruiser. I replaced the Cutlass Bearing in the stern tube last year at haul out. Six years before I had removed the old fashioned Stern Gland and replaced it with an Orbitrade rubber stuffing box. Each time I checked and adjusted alignment.

My coupling bolts are checked, by me, at the start of each season. The OE bolts on our boat are UNF thread, HT steel and have nyloc nuts. I have NEVER found them loose.
I dont use a torque wrench either, but 60 years as a pro mechanic has given me the 'feel' for tightness.
My previous life as a semi pro motorcycle racer who prepared his own bikes meant I trusted my preparation. You dont want bits coming loose around the Isle of Man TT course!
The 5/8 diameter HT bolts used on the coupling are well strong enough to drive the boat with a large safety margin.
As long as they are tight........................

I just used nuts and lock washers, but maybe I should have used nyloc nuts?

 

[rslifkin]

I just used nuts and lock washers, but maybe I should have used nyloc nuts?

Nuts and lock washers should be fine if the hardware is appropriately spec-ed and in good shape (and tightened appropriately). That's how my couplers have been assembled for 36 years with no issues.

 

[janice142]

Goodness gracious, Cardude!!! You do have quite the adventure. I'm impressed that you were able to fix the problem while in the midst of it. Congratulations.

Just a thought though... aboard Seaweed I store spare shaft zincs just forward of the stuffing box. This way, should the worst occur, my shaft won't go back far. It's an old trick that does nothing to prevent galvanic corrosion. Basically, I know where my zincs are, and the shaft won't fall out.

Picture (and the zincs are further forward, this is the only picture I could find)

 

[rslifkin]

Goodness gracious, Cardude!!! You do have quite the adventure. I'm impressed that you were able to fix the problem while in the midst of it. Congratulations.

Just a thought though... aboard Seaweed I store spare shaft zincs just forward of the stuffing box. This way, should the worst occur, my shaft won't go back far. It's an old trick that does nothing to prevent galvanic corrosion. Basically, I know where my zincs are, and the shaft won't fall out.

Picture (and the zincs are further forward, this is the only picture I could find)

That's a good trick! I always make sure my shaft zincs are placed so they'll hit the strut before the prop hits the rudder in a worst case scenario.

 

[cardude01]

Goodness gracious, Cardude!!! You do have quite the adventure. I'm impressed that you were able to fix the problem while in the midst of it. Congratulations.



Just a thought though... aboard Seaweed I store spare shaft zincs just forward of the stuffing box. This way, should the worst occur, my shaft won't go back far. It's an old trick that does nothing to prevent galvanic corrosion. Basically, I know where my zincs are, and the shaft won't fall out.



Picture (and the zincs are further forward, this is the only picture I could find)

Great idea! Thanks.