Not going to happen again!!!

So, Steel melts in that one exact spot before anything else the brass, aluminum...not even a hint of discoloration on the strut.. gotcha.

Admit it, something was out of balance and the point at which the shaft enters the strut was the pivot point...paper clip theory...

Prove me wrong, I'll wait.....

Isn't that blue Bell Ray grease a little thick???

Ken

K F Wheeler said:

Isn't that blue Bell Ray grease a little thick???

Ken

Click to expand...

It is,,,, nice and tacky...sticks to everything...messes up your nice clean boat... but it works.

Daniel, do you know what kind of thrust washer or bearing was used on this set up?
The reason I ask is because I have seen the same thing happen when using a ball bearing thrust washer with a hardened steel washer! Just thinking out loud

And the Bel Ray grease, best stuff out there!

DON MAHER said:

Daniel, do you know what kind of thrust washer or bearing was used on this set up?
The reason I ask is because I have seen the same thing happen when using a ball bearing thrust washer with a hardened steel washer! Just thinking out loud

Click to expand...

It is a slip fit bushing with welded stub cable run with 3/8" of gap.
You don't use thrust washers with this setup. You can't make an iota of contact with a welded stub cable setup.

He had been running the same length cable for a while so I do not think it was anything more than it went dry.

Wasted wages said:

So, Steel melts in that one exact spot before anything else the brass, aluminum...not even a hint of discoloration on the strut.. gotcha.

Admit it, something was out of balance and the point at which the shaft enters the strut was the pivot point...paper clip theory...

Prove me wrong, I'll wait.....

Click to expand...

It is comical that you think it was bending back and forth enough that fatique heated it up until it melted. No need for me to prove that isn't what happened. We all know that did not occur. I will not waste my time to try to get you to believe something you won't.

The aluminum was getting super cooled running it the water. The shaft is spinning actually capable of making the heat/friction that happened here. Now which is going to get hotter.

Pretty hard to heat aluminum when submerged in cold water flowing by endlessly.

It doesn't matter how it happened. Just sharing cool pics didn't intend to argue about how it happened because it really doesn't make a chit and neither you nor I can prove anything nor do I need to.

Green grease beats even the Belray waterproof grease as many have found out after actually trying the Green Grease. It does have better lubrication and water washout resistance. Try it once you may be surprised at how much better it is. Easy to find too even locally for most.

...Wha What's the "Green Grease??!??"
If the set screw were throwing it off, more than likely the shaft would be bent in the opposite direction!
Never had a problem with drive cable other than collet being junk...

Ken

Why would the shaft be bent in the opposite direction? The shaft will always be pulled toward the heavy side and, since the prop is beyond the point of the extra weight, it would be thrown in the same direction. With that much mass being slung away from center, it would cause the shaft to ride on the edge of the stuffing tube/stinger and create heat through friction, allowing the shaft to bend at the point of highest heat/friction

^^^exactly ^^^

Once the prop/shaft/ drive dog wore at the pivot point, out of balance condition would only continue to get worse as the shaft/bushing began to fail and the clearance became greater... the hotter it got, the more pliable the shaft became until it folded.

Had it been a run dry issue, the shaft/ bushing would have been smoked to the point of seizure
along a greater distance, not at a single point like this one did.

I've done failure analysis on engines, rotational equipment and refrigeration compressors for over 35 years. It is my job to figure out the root cause of equipment failures. You would be amazed at how little it takes to move something out of its harmonic range and cause oscillation to occur.
The higher the RPM, the more pronounced it becomes... I've seen copper tubing failures occur on refrigeration racks caused by a compressor 6ft away with a broken rod. Figure that one out.

I had a 200 hp direct drive AC skid that broke a
2 5/8 Discharge line going into the water cooled condenser mounted below the compressor.

Everone swore there was a problem with the drive coupling. I didnt buy it...out of round was less that half a thousandth in all four axis..

I found the harmonics caused by the natural resonance of the discharge valve plates in the compressor was causing the discharge muffler to
move back and forth 10 to 30 thousandth...

Guess where the point of failure was on the tubing? ...that's right, the pivot point were the pipe entered the tank.

It was undetectable to the naked eye..used an oscilloscope and strobe with high speed camera to catch that one... replaced the tube and fittings, added a 40 lb block of steel to the muffler to dampen the oscillations and everyone went home happy.

I think in a situation like this it would be impossible to say what direction it would bend. You have the engine still trying to run. Hydrodynamics doing it's thing on the prop. Don't forget what water is like at speeds this WAS running for a time. And a considerable amount of weight on that end of the shaft trying to swing ANY direction it can! INCLUDING STRAIGHT AND INLINE! Not for long but, still possible. You can't tell me it instantly bent and froze that way...

Ken

K F Wheeler said:

I think in a situation like this it would be impossible to say what direction it would bend. You have the engine still trying to run. Hydrodynamics doing it's thing on the prop. Don't forget what water is like at speeds this WAS running for a time. And a considerable amount of weight on that end of the shaft trying to swing ANY direction it can! INCLUDING STRAIGHT AND INLINE! Not for long but, still possible. You can't tell me it instantly bent and froze that way...

Ken

Click to expand...

Nope, wouldn't even try to argue that one. The density of water COULD have been a factor, no way to tell without some serious test equipment and a test tank to run it in.

Insert joke or double entendre here on the best way to lube your shaft.