What causes this?? Broken hub

[cojab]

I was checking a prop I just got for my boat and when I pulled the old one off, this is what I found.
So, as the title says, what causes this. Also what can this do to my engine, performance etc.

[Pacific NW Ron]

Wow, I'm not sure what caused that or what other damage it might have done.   One thing I can say it ain't good.  From what I see I'm surprised you old prop was still turning or for that matter even still on the shaft.  I can't tell for sure but is that your prop shaft or where exactly was it in relation to the prop?

[cojab]

Everything was completely in place when I pulled it apart.
In fact, after pulling the prop off, the big chunk from the back of the hub slid out of the prop and I was able to place it back in the prop and it fit in perfectly where it had broke. After sliding the rest of the hub out is when the rest of the pieces came apart.

[Lipripper]

Everything was completely in place when I pulled it apart.
In fact, after pulling the prop off, the big chunk from the back of the hub slid out of the prop and I was able to place it back in the prop and it fit in perfectly where it had broke. After sliding the rest of the hub out is when the rest of the pieces came apart.

Dang that don't look or sound good. I don't know anything about motors but I would think you need that part to make it run right. 

[cojab]

Dang that don't look or sound good. I don't know anything about motors but I would think you need that part to make it run right. 

Yeah I would agree with you. Thanks for looking and replying Lip. Your a class act sir!

[Capt. BassinLou]

Cojab, most of the time, a broken hub is caused when you hit something at full throttle. But, you will notice slippage if that was the case, shortly after. There are other causes like extreme heat and such, but if you just noticed it now when conducting a propeller check, you may never know what was the cause. Take the serial number off your outboard and/or prop for the correct hub replacement. Good luck.

[cojab]

Thanks Lou. I was thinking the prop had to hit something pretty solid but there is not so much as a scratch on the prop. It is stainless but I would still think it would leave some kind of scar.
The other thing I was thinking is that this boat sat for as far as I can tell 6 or maybe even 7 years without being used at all. Is it possible this part degraded sitting and maybe a very light hit on something shattered it?
Thanks for looking Lou.

[Oldfart9999]

I believe that part of the hub is a type rubber and it dried out, I hope one of the experts chimes in.
Rodney

[cojab]

I think its a Flo Torq type hub OF. It's a hard type of plastic or composite of some sort
Thanks for the input sir.

[Mike Cork]

First, I've shattered lower units by merely ticking something at full throttle, it's all about the angle and the position of the motor and compression strokes when it happens.

With it sitting so long, I would imagine it was extremely degraded and simply putting it in gear caused it to shatter.

I'd replace it and keep an eye on it but I bet you won't see any issues.

Thanks for posting it though, I've never seen one do quite that 

[cojab]

Thanks Mike. I appreciate it.
I've posted before about some idle speed lower unit clunking I've had. I'm curious now if this is what was causing it. I'll have the boat on the water Tuesday and I will find out.

[Mike Cork]

Not knowing how long it's been cracked, it certainly could have been

[BassBUFF]

First, I've shattered lower units by merely ticking something at full throttle, it's all about the angle and the position of the motor and compression strokes when it happens.

With it sitting so long, I would imagine it was extremely degraded and simply putting it in gear caused it to shatter.

I'd replace it and keep an eye on it but I bet you won't see any issues.

Thanks for posting it though, I've never seen one do quite that 

Bingo! Agree. Combination of everything. Buy 2 and keep a spare in the boat along w/tools to change it if needed.

[merc1997]

it says here that you have hit something.  that type of hub is made to do just what it did to protect the engine.  but, i am not for sure just how it did not start slipping.  you need to get you a spare hub kit to keep in the boat.  it is simple to replace and get back to running when you spin one.

bo

[big g]

I think if you hit something while running hard there would have been damage to the prop.

[cojab]

it says here that you have hit something.  that type of hub is made to do just what it did to protect the engine.  but, i am not for sure just how it did not start slipping.  you need to get you a spare hub kit to keep in the boat.  it is simple to replace and get back to running when you spin one.

bo

Thanks for the input big g and Bo.
I truly cant think of anytime I have hit anything and there is not a mark one on the prop. The only reason I think it didnt slip is because it was all together like it was whole inside the prop and the prop was keeping it all together. If I didnt slip it out of the prop I woud have never seen that it was in pieces. In fact, when I first turned the prop over, just one piece of it came out. I put it back in and it matched up perfectly and you wouldnt even know it was broken. When I pulled the rest of it out is when it all came apart.
I did replace the hub and also have another prop and complete hub in the boat now.

[Oldfart9999]

Good reason to pull the prop and inspect it at least once a year.
Rodney