My prop shaft has a substantial bend aft of the p bracket. I have no idea how it could have happend. The last time I used the boat I motored for about an hour with no problems. The next time I put it into gear the whole boat shook so bad I immediately stopped the engine. I had her moored in a berth with many boats around that had no damage. My boat was stroke by lightning and I had a lot of electrical damage at the time when the shaft got bent. Initially I thought the p bracket must have cracked from the Lightning strike. The insurance adjuster says that something must have hit the shaft while the boat was moored. I think that's impossible because, it is a one inch shaft with about 5 inches that extends out of p bracket. The end is only after the p bracket. The prop, a folding 2 blade, does not have a mark on it. Does anyone have any advice or think that lightning could have done that? I have no idea how this could have happened
I need advice Bent prop shaft
- Thread starter JensJaunt
- Start date
:stirthepot: Well.......I don't think lightening could have bent the shaft, but during a storm something (a log perhaps) could have been swept under the stern and caused the damage. Boats on moorings do bob about quite a bit during adverse weather. Boats in slips might contact the dock due to wave action. Advice? Haul the boat out to check the situation. Get the shaft replaced. Check the strut for damage or loosening. Have the prop balanced or refurbished.
My slip is on the second closes row to the retaining wall, with 6 more rows to entrance to marina, and is the third closest to the shore wall. The marina is full and I would think it would be hard for boat to make contact, with the floating dock, to cause damage to the shaft. The p bracket itself was not damaged but the fiberglass on cracked. The bend is an area that would have been insider the sleeve of the prop.
I have her out of the water now and want to make sure that there is nothing else wrong. Is there something else that could be going on that I should get checked. I am at a loss for how this could happen?
did the yard lift your boat with the lifting sling by the prop ...that is the only thing i can think of that would have caused that based on what you have said ...this may well not be the case but it is a possibility........
Were you present when she was hauled? Mystery damage like this is why I always try to be there when mine's hauled or launched, and recently I've been shooting video of the process. The most probable explanation is that they caught a strap on the prop, unless you were there and know they didn't. Without a witness though, it's just conjecture.
I was there and the sling was not even close to the shaft. I have no idea how this could happen. I was away for a month and when I came back there was some serious lightning damage. When I put it in gear to leave the slip the shaking was so bad I did not go out. Everything had been fine before I got hit by lightning. I am worried about the transmission and engine mounts but I don't know much about these kinds of things.
Based on the history you describe your shaft is probably not bent. Instead - your two blade is not deploying the second blade hence putting the entire assembly out of balance.
If I am wrong about the prop, then please tell us exactly how you verified the shaft itself was bent, by how much, and the location of the bend.
By the way I do not know what you mean by "p-bracket" so we need a definition. In addition we do not know the distance of your shaft (transmission to the strut, if you have one) nor the distance from the strut to the prop.
Charles
If I am wrong about the prop, then please tell us exactly how you verified the shaft itself was bent, by how much, and the location of the bend.
By the way I do not know what you mean by "p-bracket" so we need a definition. In addition we do not know the distance of your shaft (transmission to the strut, if you have one) nor the distance from the strut to the prop.
Charles
Uummm... post #3 says he is hauled out and has eyeballs on it. I once hit a crab float at speed and could hear the whack as it bounced off the hull. Then the boat started vibration. I shut the engine down and sailed to Solomons Island harbor, thinking I could limp into a slip on low RPM. When I restared the engine, all was okay. I think the float partialy closed the 2-blade folding prop. All was okay.
Apologies - I was evidently not clear in my proposition.
The proposition is that the shaft is dead straight and instead the 2 blade propeller - a folder - is only "unfolding" 50%. And the reason I propose this is because there is nothing in the history which could possibly explain a bent shaft, whereas there is plenty in this history to implicate a compromised folding propeller mechanism.
Charles
The proposition is that the shaft is dead straight and instead the 2 blade propeller - a folder - is only "unfolding" 50%. And the reason I propose this is because there is nothing in the history which could possibly explain a bent shaft, whereas there is plenty in this history to implicate a compromised folding propeller mechanism.
Charles
I checked the prop, both blades move freely, there is not a mark anywhere on it. The p bracket is support or strut that the propellor shaft goes through immediately before the prop, it hangs down from the hull. I have a video demonstrating the bend in shaft. It appears to be bent at the top of the hole for the prop key. I was very surprised because the sleeve or collar of the prop goes well past that. I will try to load some pictures.
I have felt the effects of the folding prop only partially opening, there was some unpleasant vibration, but the recent vibration was shocking. I went under to see if something was wrapped around the prop. It was clean and both blades moved freely but there was a fracture line on the strut (p bracket) that I thought was the source of the problem. The boat shaking affect had persisted to the extent that I had the boat towed to the yard, which is part of the marina I am moored at
Is it a bronze or a stainless shaft? If your strut is fractured, you have damage to the laminate structure around the strut and the shaft it bent it certainly indicates a very significant impact with something pretty solid. Any damage to your rudder? Seems like anything that would hit your shaft that hard would probably hit the rudder as well. Do you have any submarine traffic in your area? :>)
Not yet but the way the bills are piling up it might be soon. The boat was tied up at the pier, and my boat is in the farthest corner of a very large 4 wall marina with only one way in or out, at the opposite corner.
Attachments
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.
Do you have a pic that's more "along the shaft" that shows the bend?
Maybe you could remove the zinc's and put a straight edge against the shaft?
Chris
Maybe you could remove the zinc's and put a straight edge against the shaft?
Chris