Started out with 3 blades, but now I got two.

It was so nice after church last Sunday, My 11 year old son and a friend of mine, went out for an afternoon of boating. After a very enjoyable time, and on the way back to the house, 1-2 miles out from the mouth of the river, we picked up a huge, and sudden vibration, and lost 10mph almost instantly from the mid-high 60s we were doing. At this point we were done. This area of Charlotte harbor is 10-11 feet deep, and we pass through this area every we take one of the boats out.

What you are looking at, is a Mercury Racing, 3 blade cleaver, 15x32LH, double lab, prop from the STBD side of my 2007 30 Skater.

This prop is part of a pair that was purchased Sept 10, while the boat was at TNT for the most recent set of setup and dial-in changes. I got the boat back Sept 28, and have put 14.5 hours on the boat and props since then.

Damn, Frank. Stress failure or did you hit something?

Man thats nasty. If it makes you feel any better I have quite a few pics of my boat missing the entire propshaft and prop. I would love just to damage the prop.

My opinion (based on 30 years on engineering, 25 years of boating and 10 years of offshore racing), stress failure, or possibly a materials failure in the original casting.

First possibility, if you look closely, you can see that it seems to have first failed on the trailing edge, causing the back portion of the blade to be pushed away from the direction of the positive pressure, towards the negative pressure side. This seems to have caused a deformation and rotation of the blade, from back to front, causing the leading edge to fold over into the positive pressure side, tearing off. The back 1/3 looks like a clean break, the middle 1/3 looks like a diagonal rip, and the front 1/3 looks like a tear.

The second possibility, is that it first failed in the leading edge, and that traveled from the front to the back. The inward flare of the leading edge, seems to support the first conclusion much more that the second.

The third possibility, it that I hit something. While it is impossible to be 100% certain, the bottom of the boat and the gear case, look perfect, not even any scratches or marks. I see no evidence of any impact, and the directionality of the break seems to support the first conclusion.

We will see what Mercury Racing has to say after a carefull inspection.

In all my years of boating and racing, I have not hit anything or damager a prop. In the past I have been very fortunate.

While racing we routinely twisted the propshaft so bad, that I went in the garbage after each race, but it was a Bravo drive with a 660+hp, small block chevy, spinning 7000+rpms.

Mercury Racing has been very good through the years, standing behind the products. We will have to wait and see what they derermine in the inspection.

Yeah I had this happen to me too. I talked to a few people and they said that if I ran a high X dimension and Labbed props I would only get 20 to 30 hours out of a set of props. So when my starboard side lost a blade I went back to non-labbed props and have not had a probelm. I also run my x-dimension a little more conservative now too.

Hope this helps
Don

Thanks Don

Something to consider.

Ask Brett at BBLades if he can fix it. LOL

At least it was not a new Merc CNC or Herring 5 blade.

Already went out to Merc Racing.

I will keep you all updated as to the outcome of the inspection.

Got official notification yesterday, Mercury Racing will replace my prop, at no cost to me. It seems they agreed with my analysis of the failure (see pictures #243, analysis #246).