I need advice Bent prop shaft

[Captn TJ]

The blade both move freely, but they being held in the position by gravity. The top one is laying flat and the bottom one is hanging out but when rotated it was reversed. They were both free. I checked both in the water and on the hard.

I believe the bigger question - especially with the growth on the prop blades is how much is the prop contributing to the vibration and the resulting issues.

With all of the barnacles you have on it - it's probably out of balance (even though it moves freely)

 

[JensJaunt]

It is hard to see the bend in the still picture but I cannot load the video. It is bent from the top of the key way. There was a lot of growth on the prop, I live in Singapore, we get a lot of growth, but that was not the problem. Trust me the vibration you get from growth on the blades is nothing like when the shaft is bent. I had not cleaned it because I was waiting haul out for insurance work because of lightning strike. We thought the Lightning had exited the p bracket (prop strut), because there was a obvious crack seen when I dove under the boat, but it turns out the shaft was bent. The folding prop was dirty but did not have a mark on it. The sleeve or cuff of the prop covered the area of the shaft that was bent. I cannot explain how the shaft could bend where it did, it only sticks out of strut about 7 inches and it is one inch thick.

 

[jibes138]

Here's a thought for you. Did someone in the past heat the shaft drastically to try to get the propeller hub off? This might have effected the strength of the metal by annealing it. Depending on how various metals are heat treated can dramatically change their strength. The keyway portion of the shaft has the smallest cross sectional area and concentrates stress from the discontinuity of the keyway cut. Couple all that with an imbalance in the propeller if say one blade stuck momentarily before opening and it might have caused the bend. The prop blades might have been free when you checked them but perhaps growth has stuck one on initial startup and then freed itself up once the growth broke loose? I only suggest this because the shaft looks a little discolored near the end of the key slot.

 

[kloudie1]

Was the prop hub just a tiny bit loose on the shaft? That style folder adds a large amount of overhung (cantilevered) weight past the end of the shaft.. If not seated and lapped onto the shaft taper, the shaft might have been bent by a second or two of one blade not extending.. woould have shaken from the start because of the blade not extending and then because of the shaft bend after the blade freed up ??