Went out for a run today and broke a prop........I didnt hit anything......did I get a bad prop? Its a merc lab 3 blade cleaver 15x30.

How many hours on it? They don't lasr forever,their under alot a stress at WOT. Thats the price we pay for these toys.

Join the club, I had a 30 Spectra and lost a blade on a prop on a pair of 300x's in 70' of water in LOTO by big dicks with the spares in the truck

That's about the same point that I broke my hydromotive. I had the prop for only a couple of hours before it let go. I chalked that one up to fatigue from it surfacing. That's why those cleavers are so thick.

Shhheeesh...that cant be good.
What does it do to the drive components when they let go at RPM?

Mine 34 let go at 8000 rpm!

I had a 34'' merc let go last year. killed the bearing carrier in the sportmaster on my 300pm

This just happens. Sometimes they last for a long time and sometimes they only last for a few runs. We lost a blade when we were running the Top Gun and we lost another blade last year in the Gladiator. It does not appear that either prop hit anything because there weren't any other marks on the other blades, the drives or on the boat either time. They just sheered off. Both sets were lab finished, which probably didn't help matters. The one on the Top Gun was a 15 1/4 X 32 and was on a Bravo XR. The one on the Gladiator was a 15 1/4 X 34 and was on a Bravo XR Sportmaster. The one that let go on the Top Gun lasted all season and broke at the World's in Key West. The one that let go on the Gladiator was brand new out of the box and broke during the Spring shakedown run right after we de-winterized the boat. That prop lasted all of 45 minutes at best. Oh well, that's how it goes sometimes. I now have a couple of souvenirs to hang on the wall.

Here is a better picture. No other marks on the prop. It just looks like the blade was put in a vise and snapped off. It's amazing what water can do.

This is a common sight and it will become even more so. Power gets bigger every year. When the Bravo 1 was designed 330hp was a big deal. Now 750 plus is put through Bravo1 drives on a regular basis. The props on the market today designed for the Bravo 1 drive have limitations. The motors of today have a lot of power and exceed the design parameters of the drive and propellers.

The 525 really put things over the edge. This motor seems to eat drives and propellers for breakfast. Racers who ran the hp500 could go all season with the same drive and prop. Now with the 525 they are rebuilding the drive every couple of races. Props can't stand up to a season of racing, not even the single engine boats.

If you are having a prop worked on make sure the prop guy knows what kind of power the boat has. It's very important. When we work the same model prop for an outboard it is very different than when that same model prop is going on a 525 powered boat.

It seems as if the solution is to go with more blades. The 6 blade props seem to be holding up very well. The greater number of blades helps to distribute the load among more blades thus reducing the load on any one blade.

Matt