shaft coupler bolt

Had a great run with the new boat from Pensacola to her new home in Pass Christian. Stopped over at Dauphin island had a great meal at the seafood restaurant / bar and they let me tie up for the night. Checking the engines the next morning, I discovered a shaft bolt in the bilge and the remaining shaft bolt with a bit of broken seizing wire still attached. The bolt threads were too far gone to be re attached so all I could do was tighten the remaking bolt and double seize wire that one. The delivery captain told me he had some vibration in the engine on the way from Punta Gorda to Pensacola. Now I know why. I have never heard of a bolt that was wired coming unbolted.

I've never heard of that either. I think I'd take a close look at the engine mounts to see if anything is broken there. I wouldn't leave the dock until you figure out what happened.

I was lucky to see that bolt. This is the type of problem that you may not see until it is too late. If that second bolt had come off, and is was not tight, you loose your shaft out the back and start taking on water in a big way!

don't think so. The flange usually will stop the shaft if it doesn't hit the rudder and jam it in position first. Not good either way.


I agree you should check mounts and alignment then use new bolts.

What bolts came out? Description implies only two bolts? So are these the clamp bolts on a split coupling? Or the bolts that hold shaft flange to gear flange?

Buy a pair of these,

Use these techniques:

To do something like this:

Make sure the fasteners are properly torqued first.

Ski in NC said:

What bolts came out? Description implies only two bolts? So are these the clamp bolts on a split coupling? Or the bolts that hold shaft flange to gear flange?

Click to expand...

I am thinking set screws into dimpled shaft...really the only ones I have seen wire tied....maybe?

Probably a split coupling with two pinch bolts. Nylock nuts would do just fine as well.

...and yes I own lockwire pliers and a few rolls of SS wire

If you are really worried about losing a shaft out of the boat, you can install a shaft collar on the shaft in front of the packing nut or seal.

OK, let me clarify the bolt in question was a set screw. This is the bolt that you generally see in the coupler with a portion of that bolt going into the shaft. Usually there is a second screw 90 degrees offset from the first. Both bolts have a hole drilled through the head to facilitate a wire and both bolts are then wired together. I will post a pic if I can figure out how to post.

here is a picture of the set screw.

Square headed set screws. Do yourself a favor and add a locknut to each one. Lock them to the coupler body. Then safety wire the setscrews to the coupler. That way if one safety wire comes off one the second is still secured.

When you get a chance examine the shaft dimples vs the set screw ends.
A friend had a similar problem with those screws coming out and he did have the shaft whap the rudder.
Whoever turned the dimples and the pointy screw ends did not match the tapers, not even close. I redid the ends so the dimple taper and the screw taper matched and no more trouble.
Redid the safety wiring.