Prop slung a blade

[roda]

Neighbors boat lost a prop blade on the 3rd pass this AM. Coming out of the hole.. bang. '05 MC 197 non-slot, original prop, just under 300 hours. Scarred up the bottom of the boat as it left the scene.

 

Has anyone else ever had this happen?

[Tuney]

I have heard of it happening to a few people. There are a number of complaints with Stainless Steel props but people have reported it happening with Nibral props as well.

[Bill Gladding]

Our group had a couple of MC TT boats and I believe it was the '05 that threw a blade and dinged the hull bottom.  I recall it was an Acme and it was replaced for no charge by Acme.  We had a couple hundred hours by the time the blade came off.  We paid to fix the ding in the hull bottom ourselves.

 

[HO 410]

We've had it happen twice. Similar to Bill it happened with a couple hundred hours on the boat. I thought they were OJ props but I could be mistaken. The MC dealer didn't quite know how to handle it. As in they said we hit something and they would not submit a warranty claim (let's just say they don't have a firm grasp on how a promo boat is used) Dealing directly with the prop manufacturer was much easier.

[DW]

Seen it happen on a 3 blade SS CVP prop circa 1996.

[Thomas Wayne]

We had an OJ prop that shed all THREE blades suddenly and unexpectedly.  Of course, it turned out to not be covered by the warranty, due to the unseen gravel bar we hit at speed...

TW

[Bill Gladding]

I should have said I don't remeber whether it was Acme or OJ but it was the stock propeller that came on our TT boat.  I was able to prove we didn't hit anything because I found the broken off blade on the bottom of the lake.  Other than the break it was in perfect condition.

[Deke]

Anyone know of a way to check for this?

[Thomas Wayne]

Count your blades - three is a good total, unless you have a four-blade prop.  Then it's bad.

TW

[HO 410]

X-ray maybe. I can't say that we inspected the prop closely after every set, but it was very much a without warning thing. It didn't happen to the first skier of the day. It didn't happen on the first pass. Coming through the gates, the boat began to vibrate severely. After limping back to the dock, the 4-blade prop had transformed into a 3-blade.

[Deke]

There are 3 kinds of waterskiers. Those that can count and those that can't.

[east tx skier]

I've seen an OJ prop do this.  Tell them to give Eric Johnson at OJ a shout.  It's obviously a defect and I have seen him be pretty good about handling it.

[roda]

Yes it was an OJ prop, 4 blade. He plans on calling them & I'll suggest asking for Eric.

 

Thanks

[teammalibu]

I had an OJ that was my favorite prop ran smooth as silk. One day I happened to take a look at it and it had a crack

over a half inch long in one blade. I guess that should be on the to do list of things to check. 

[boarditup]

There are several potential causes including a soft grounding, turtle hit, vibration, metal fatigue, blade thinning, etc. that can cause this issue without any detectable mark or indication on the prop.  Most of the time, if it is a mfgr defect, the blade will come off in the first 20-hours of use.  The typical problem is a void in the blade during the casting process that does not cause a surface defect.

 A prop is a wear item.  They do not last forever.  You will find the blades get thinner and weaker as it ages.  Water and suspended solids will abrade the blades over time. The torque of the hole-shot will flex the blades and metal fatigue will result - potentially resulting in a thrown blade.  However, most people have to replace their prop before it wears out due to contact with a hard object - like a trailer or the bottom.

[DW]

Crack testing will show impending problems.  One can purchase crack test kits from good industrial supply houses or racing suppliers.  It is a three spray process with dye and penetrant.

[Bill Gladding]

I agree with Karl in general about his prop comments but I think the failures that are being discussed here are a latent defect in the propeller related either to materials or the machining process.  I recall the crack on our propeller blade began at a machine mark and obviously happened over an extended period.  There were numerous beach marks all the way to the point the remaining metal was no longer able to support the load when the propeller blade finally came completely off.  Lots of causes for that type of failure kudos to OJ for taking care of their customers that experienced the problem us included.