teeitup

Sent a prop in to be lab finished for max top speed. When I got it back I had more RPM and less speed. The guy said he would fix it by putting the cup back in it. When I got it back the boat was back only to the original speed. I just decided to forget it and take the $400.00 loss. Problem is that after the 1st weekend I noticed one blade was cracked from the leading edge to within 1/2 inch of the trailing edge. The crack at the top was completely open and offset.
The shop says it was a coincidence and that it was not their fault and I was on my own.
Weigh in guys & gals-Did I get screwed? Should I ask for a new prop?

zt260

What kind of power are you running? And what prop?

mwdill

had a simalar crack ,turned out to be an air bubble in the casting ,seems like certain mercury props have this problem , got it fixed no problem, just call Matt and Julie at Throttle-up.

articfriends

iTrader: (1)

Prop tuning isn't always a exact science,was there a performance guarantee? Sounds like the thinning it out made it crack though,it could have had a air pocket in it that would have been fine forever if prop had never been modified. So I guess its sorta the chanch you take but your probably wondering do you throw more money after bad,is it just going to crack somwhere else? I don't know ,I'd probably get it welded and run it as a spare,Smitty

Macklin

You take your chances with lab jobs. That's why I decided to go back to stock props. Better cruise speeds and stronger blades. I'm able to run WOT less than 1% of the time anyway. You may have to eat this one.

Your best bet is to stick with real professionals like Throttle Up, Merc, etc.

bbladesprops

There is a common misconception that Lab Finishing a propeller decreases its integrity. In fact, I've heard people claim 10-15% loss in the strength. This is simply not true. The fact is the propeller has had the inconsistencies removed through our Lab Finish process. It is cleaner through the water. If there is a flaw in the blade we will more than likely find it during the Labbing process.

That being said, If you hit something with one of our Lab Finished propellers, you will more than likely damage it more than a box stock version.

As far as voids in the castings.......yes there are problems with this for "every" manufacturer. The voids are created by the ceramic dust used to form the mold. When the casting is poured the dust particles can be trapped in the casting and disintegrate from heat to leave a small hole. If internal far enough, it can't be seen. If on the surface and not found, the media finishing process to give the gloss finish can hide them. When we finish our propellers, we use a satin finish (for many reasons). Contrary to what some say or lead you to believe, this finish can actually open these pours to the naked eye and allows us to weld them. Putting a high gloss finish on can actually close and hide the voids and holes (it looks pretty but has no value to the performance of the propeller). The voids that are internal and not found can behave the same as a stress riser. Flexing of the blades can focus on that point and eventually cause the crack to form from the inside out.

There is other reasons cracks can form in propellers. Cold rolls formed while pouring the castings can also cause cracking. Not repairing minor nicks can cause stress risers. Knife edges have a tendency to nick easier and create the stress risers.

Ultimately, no propeller shop wants any customer to be less than happy about the propeller work they do. But, sometimes the prop shop can only be as good as the piece of 15-5 stainless they are working with.

As far as the performance issues you experienced, that's between you and your shop.