I have a 525 bravo xr with sport master lowers 2007 donzi 38zr I have broke 4 Maximus props. 2-32's, 2-34's. Both sets were labbed and cut down to 15-1/4 They just throw an ear off after 2-3 weekends of boating. It doesn't matter if I'm running hard or not. Would a hydromotive prop hold up better? Drive spacers? I'm sure others are having the same problems any help would be appreciated.

when a prop gets labbed,the blades get thinner,that weakens them.try one that is not labbed.

All (Mercury, Hering, Hydromotive) investment cast propellers will through blades if the casting has flaws or just over time (there is a life cycle). If the boat is set up aggressively like I'm sure yours is since it is a ZR, it can aggravate the situation and break them faster.
Spacing down can definitely help if your props are surfacing a bunch. I'm guessing they are with your set up. But this will decrease speed as well.
Shops can keep the props thicker during Lab Processes but the performance changes as well.
Labbing to the correct recipe is your next move.

Brett

Brett thanks for your input. I sent all four props to you this winter right after I bought them and bblades cut them down and labbed them. Did I ask for the wrong thing? What are my options now? Any suggestions?

Either post here or PM your name to me so I can check your file. I'll look at the recipe and see what changes can be made.
Like I stated above, your boat will more than likely be tough on all props because the bottom and possibly the X dimension.
Compromising performance for durability may become a requirement.
You mention you broke all 4 props. Did you break 2 at a time, 2 times? Strange.

Brett

I broke one prop at a time. Never broke 2 at a time. Dale Minnick

Ok,
I did the research.
You shipped us 4 Maximus props. One was Labbed to a custom recipe at Merc Racing in 2006. That Merc prop had their new blade configuration for Labbing (changed from my design implemented in 2003). They changed it to expedite production but the performance was poor so they changed back to the original.

We matched the stock 32 you sent us to the Merc Labbed prop as requested and Labbed the stock set of 34 per our conversation to our standard template with a slight TE adjustment.

This all points to the fact that your set up is going to be hard on cast propellers. These Maximus props you have are a thickness used on 80% of Labbed propellers. Basically it is pretty thick. The major majority of propellers being run at this thickness are not breaking.
So, your option is to run propellers stock or better yet have the thicknesses adjusted just thin enough to match them. The old saying is.....and it is very true..............Thin to win.
But, some boats can't handle it.

I'm curious, if you broke one 32, what did you run then to break the opposite rotation? Likewise, if you broke one 34, how did you run the boat to break the other 34? We never made you any matching replacements.

Brett

My mechanic who has built motors for me for other boats Eric Betty from EB marine in Nashville let me borrow some single spares he had because he has experienced the same problems with the maximus props. I need some props but was posting on here to find out what others have done to correct this problem. Brett I appreciate your input and I'm not trying to blame you for anything. I will buy or send you my next sets of props to dial in but just want to make sure I don't waste any more money on props than I have to.

Eric is awesome. He does great work! We have worked together for years.
It's all good. I never took this any other way other than that .......Let's figure out what we need to do to get to the next level.
Bounce ideas off of each other, use our resources, and be smart moving forward.

Let me know what we can do to help. That is the beauty of this forum. It is meant to share
ideas, learn and grow our hobby, I mean passion.

Brett

I have lost blades on 3 of my Maximus props since 2009 on my ZR. Think Donzi has the X dimension too high for max performance not considering that the customer is stuck with a constant cycle of buying new props. I think the answer may be to sacrifice some speed and put spacers in to get the props more in the water as stated above. I have yet to do that.

Bob