Adrenaline Junkie

OK, so I have a 2007 36' Eliminator Daytona Coupe with twin Ilmor 625's Imco drives, and imco standoff boxes.

I've been running 5 blade labbed maximus 34's and 4 blade stock merc 34's.

I've seen 123mph with the 5 blade labbed in ideal conditions (spring). In the hotter weather, I've only been able to pull 118mph. With the 4 blades, I've seen 113mph.

With the 5 blades and the heat, I've only been able to run about 5600 rpms. With the 4 blade 34's I can bang the rev limiter, but am not all over them.

I tried running 4 blade 36's and could spool up rpms much past 5k and struggled to reach 100mph.

So, I've been spending most of my time on these labbed 5 blade 34's and have thrown my second blade - and am frankly disgusted with these labbed maximus wheels. Both days I threw blades were in calm seas - 1' or less. Once I was cruising at 50 and lost one....and most recently I was in a Poker run running about 103mph.

I am thinking that this labbed prcoess is thinning these blades too much and they can't handle the torque....and that I should just stick w/stock props.

Are you all having better luck w/labbed props than I?(I ran labbed 32 5 blades on my 28 daytona, for 2 seasons without ever throwing a blade, but I just had 496 hos in that boat)...just feeling like these labbed props are too delicate for 625 hp.

Should I be trying the hydromotives? Should I be trying the Herrings? Are they more durable than the labbed maximus?

MOBILEMERCMAN

Sorry to hear your bad luck. Thinned props throw blades. There are many levels of prop mods and thinning. In some cases you know longevity is compromised for speed. I have seen others and have lost races over prop failures. It happens.

In all fairness some are not the props fault. Worked props should be inspected after every run. The little nicks you can't help but to get need to be sanded out.

bbladesprops

We've been running Labbed Max props on boats with much larger HP than yours with very few failures. However, it can happen. Most people believe thinned props break because they are thin. Only partially true. Most often however the failures start from voids within the casting.(small holes left from the casting process due to technique, temp, ceramic dust etc.) The voids are stress risers and the flexing of the blades cause the prop to crack from within outward. Because a thin prop can flex more, the stress riser is worked harder. Often Labbed props that through blades would have thrown the blade even if it was left stock, it just may take longer. Surfacing the propellers also flexes the blades more and the height amplifies the flex as you go higher.

If Labbing was a guaranty of blade failure, we wouldn't be Labbing props every day. Concider having your prop guy modify the process to better suit your needs. As mercman said, leading edge nicks need to be dressed to avoid accelerating the cracking process.

A perfect casting without any cold rolls or voids can be thinned a ton and as long as no nicks occur, a long lifetime can be expected. We all know though, props take abuse. Abuse we don't even see, feel or hear. Inspect your props often and keep them maintained!

All investment cast propeller, from any manufacturer, have the same blade failure issues. I feel Mercury has the best propeller foundry and techniques in the business. As far as blade failures from each of the ones you mentioned, I'm sure I don't have to and won't make a comment. I believe their track records are out there.

GO4BROKE

It's nice to get expert info, good of you to answer so many questions Brett.
I threw a blade on a labbed prop behind a 365hp 454 mag, so I don't think it's the horsepower. The broken prop made a nice addition to my fishtank!