merc 3 blade cleaver broke
 

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.

Re: merc 3 blade cleaver broke
 

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.

Re: merc 3 blade cleaver broke
 

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

Re: merc 3 blade cleaver broke
 

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.

Re: merc 3 blade cleaver broke
 

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

Re: merc 3 blade cleaver broke
 

Mine 34 let go at 8000 rpm!

Re: merc 3 blade cleaver broke
 

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

Re: merc 3 blade cleaver broke
 

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. :)

Re: merc 3 blade cleaver broke
 

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. :eek:

Re: merc 3 blade cleaver broke
 

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

Re: merc 3 blade cleaver broke
 

With mine, I thought the engine had laid down. There was a strange but faint vibration. I pulled the throttle back and it went away. I added throttle and it got worse. I pulled off plane and put it into neutral. Engine was running fine. Put it in gear and it felt fine. Went to plane off and the whole back of the boat was jumping around. Shut it down and found the blade was gone.

Re: merc 3 blade cleaver broke
 

Speed: its a 03 30 Spectre with 300x and has about 35 hours on it.
Thanks for all the posts guys.

Re: merc 3 blade cleaver broke
 

I know "Jet set " broke a bunch of Merc props . He switched to Rollas and hasn't had anymore trouble that I know . With almost 2,000 hp :D per side ,thats pretty good !

Re: merc 3 blade cleaver broke
 

Hey Matt. Maybe it is our luck, but both of ours broke behind 500EFIs. We were fortunate that you guys were there to save the day though. For those that don't know, when we broke that new prop on the Gladiator last year it was only two weeks or so before the Daytona race. We called Throttle Up and they made us a duplicate of the broken prop and delivered it to us in Daytona. Now that is service!

Re: merc 3 blade cleaver broke
 

HotDuck,

I remember that prop of yours. If there is some type of a casting flaw it will generally show itself quickly. In your case it tool less than an hour of run time. I hope the new one has lasted longer than that.

Twin engine boats are much tougher on props than singles. There are many factors that determine the longevity of the props. The thing to remember is that props flex, and like any metal they eventually fatigue and fail.

Matt

Re: merc 3 blade cleaver broke
 

Matt, your prop is still going strong!

Re: merc 3 blade cleaver broke
 

yikes, wouldnt want to be to near that when it let go. :eek:
TizBad lost a prop/shaft on one of his #3's last year on tha cat. it was a 17x31 4 blabe cleaver. that sucker took to the air for a while i heard. now that would leave a substantial skid mark if it hit anything.

Re: merc 3 blade cleaver broke
 

Did you run over any Manatee's by chance. Maybe its stuck in one of their heads.

Can you imagine the press the Save the Manatee Club would get if they had a pic of that!

Re: merc 3 blade cleaver broke
 

I would like to see the prop blade in the manatee club members head!!!! lol!!!
I am thinking about using non-lab props this time around. What do you guys think?

Re: merc 3 blade cleaver broke
 

Dont personnaly have any experience with the lab vs. non lab props. In fact, I didnt realize that the blades would sheer off on their own without even hitting an object. I would think that a non lab prop would be a little stronger cause the metal is thicker. Thats also what cuts into the performance. One prop that I thought was pretty cool is the composite one made by Piranah. You can take the busted blades off the center hub and put new ones in. The only problem, its a plastic/composite and will not give high performance. But the concept is cool.

Re: merc 3 blade cleaver broke
 

Hey, your prop was on the other thread. Here it is! You can get it and weld it back on!

I have xtra cleavers. Will check sizes when I go home tonight. What kind of drive does it hook up to??