Losing prop blades,AGAIN
 

This past weekend On the Royal Purple poker run I chunked another blade. This is the second time . I did not hit anything and there is not a scratch on the prop.It is on my 388 Hustler standard bravo one . Why do you think this happens??

Rob

Re: Losing prop blades
 

This is the same kind of prop that did the same thing last year. Again no damage from impact and on this one it looks like the blade just cracked and tore off . The blade next to it has a crack starting in the exact same place as where the other tore :(

I know the Hustler has a high x dimensions but does any of the others have had this problem?

Re: Losing prop blades
 

Was this before or after lunch? It looks to me like someone was still hungry after the lunch stop.

Perhaps the Skeg Monster has begun dining on SS prop blades now? It has been a while since he reared his ugly head.

Sorry I have no good answer for your prop issues.
Was this the same prop you lost a blade off of before, and had it fixed? (Bad fix job.)
Was this the matched pair to the one you originally broke? (Monday or Friday set of props, and you just did not get a good batch.)
Was this a replacement prop for the one you chunked before? (No fricking clue.)

Re: Losing prop blades
 

The best price I have found so far with out a hub is 415.00 .What do you think?Do you think merc would warranty these?

Re: Losing prop blades
 

didn't they have some bad ones made in a batch I thought I read here

Re: Losing prop blades
 

They where new in 4-02 125 hours. The Rh prop thru a blade last year and I just bought a new one . Not repaired.

The left hand one broke this Saturday when we where running a bout 70mph across the causeway and I never felt anything until came off plane .It had a bad vibration at idle and getting on plane . It made about 200 rpm difference.

Re: Losing prop blades
 

unfortunately, mercury props are just not that good. they're pretty fast and relatively cheap but not the most durable props out there. we've busted a number of mercury cleavers in exact same way, no impact just threw a blade. never had this happen with rolla props but they're much more expensive too. i guess the answer is simply the fact that you're dealing with a product which has a limited life expectancy...

Re: Losing prop blades
 

Harmonic vibraton may be your problem. The prop shaft may be slightly bent resuslting in whipping of your prop blades. I have seen it happen on Arnesons and occassionally on a #6. Drop your lower and have the bearings, races and and prop shaft checked. Check porp shaft for "TIR" total indicator runout. Also have the spacers checked to make sure everything is "tight" and there is no float between the gears.

$415 for a replacement prop is pretty good.

Re: Losing prop blades
 

good stuff, expresscat... quite possibly harmonics but wouldn't he feel vibrations at all times even if the propshaft is bent very slightly? I've had this with Arnesons and Trimax drives where the damage was minimal following an impact but I still experienced massive amounts of vibration, especially with Arnesons.

Re: Losing prop blades
 

and you thought it was a plug wire :eek:

Re: Losing prop blades
 

Throttle Up told me the Bravo's are known for this. :( I wish the Hydro Q4-X's would have had the excellent cruise speeds of the stock Bravo's.

Re: Losing prop blades
 

No, I do not think you would feel it until it actaully seperated. You have a lot of distance between the prop and the hull. Every time you go through a gear you dampen the vibration significantly. That is why I mentioned to check everything else in the line shaft etc. There has to be wear on other components, even though not readily visible.

Picture the relationship of taking a coat hanger and bending it until it heats and breaks. This is what Strip's prop may have experienced. That is why there is a crack in the other blade as well. Once one went there is a significant prop imbalance situation.

I have also experienced props getting out of balance just through running. Not NORMAL running but high HP boats producing excessive load through a lot of torque. Slamming the throttles out of hole may actaully bend a prop blade or blades enough to cause this problem. So it could be the way the boat is operated. It only takes once and the damage may be slow wearing and not show up for hours.

I had to have my drives rebuilt last year. The prop shaft splines were twisted like candy canes. HP + a little flying + high RPM's on re-entry = bent or broken stuff. :(

Re: Losing prop blades
 

better take a look at who does your props...also, I WOULD, FOR SURE take that drive down and inspect the gears!...prop imbalance w/o loosing a blade can cause drive failure.

props do not go out of balance unless metal has been added or taken away...however they do fatigue and blades can change individually, most of the time gaining pitch...a drop in RPM is a tell tale sign of this...

Re: Losing prop blades
 

I've got the opposite proplem, one of my Merc. cleavers is off by 300 rpms, and is noticable getting on plane as well as anything after 3500 rpms, they are going back today.

I Had The Same situation on breaking blades on my Herrings on Radio Active, twice, it can be very dangerous with someone behind you, and thanks for the reminder, I'm still waiting (1 year later) for the replacement props.

Re: Losing prop blades
 

in one of the pic's it looks like the corner of the lifting strake is in the wake shadow of the prop. this would be an area of little or no water for the prop to grab, this would cause the prop blades to flex from that point out excessively.
when i ran spinnelli props they would break at the root of the blade after 45 min's , went to mazco's props and they are still fine today. just more food for thought.

Re: Losing prop blades
 

"in one of the pic's it looks like the corner of the lifting strake is in the wake shadow of the prop. this would be an area of little or no water for the prop to grab, this would cause the prop blades to flex from that point out excessively."....incorrect statement

Re: Losing prop blades
 

Are these stock or have they been thinned?

Re: Losing prop blades
 

it happens ,by looking the props are new. Send it back to Mercury and they will replace it. When we lab finish these props not all but some have casting holes open up. This is caused by air pocket in the casting and when put under tremendous stress it will break.This is called Fatigue.

Re: Losing prop blades
 

Would cavitation cause this? You mention a high X. Doesn't cavitation create heat? Just a thought.

Re: Losing prop blades
 

cavation is like boiling water,yes it creates friction which results in a higher temp.running this prop high in and out of the water will cause the fatigue.Or so to say BLADE FAILURE.

Re: Losing prop blades
 

one common cause for this is over trimming. a prop acts kinda like a screw, it twist through the water and creates foward push, but if you are trimmed 2 high the prop is no longer screwing through the water but instead the blades are actually slapping against the water creating a tremendous stress on the blades. this may not be the case in your situation, but food for thought.

Re: Losing prop blades
 

Damn Huge you beat me to it! If you are running your X real high like surfacing the props they will throw them!

Re: Losing prop blades
 

The Bravo shop just went thru the drives about a year ago. so should be good there . I dont feel any high spots in he bearrings and before I sent them I put a dial indicator on them to ck prop run out . I know this is not the best way but it would tell me if it was out a lot.

The props are stock never touch. Post 1 prop just happened and looks like it tore in the same area as the one in post 2 . In post 2 the 2nd pick the crack in the blade is in the exact same place as the torn blade next to it ,

The factory test report on speed on the boat the trim was set at 2.75 on the indacators . The highest I have trimed it is 3 so I dont think thats it.

I have never cavitated these props and I was told you can tell by it will look sand blasted if it is burned. They look still polished .

The x din is stock but i am sure the Hustlers are high.

I talked to Joe at Hustler and he said sometimes it happens and to just send them back to merc and they should warrenty them if they dont show any nicks or impact. So I should be OK.

I allready ordered a new one so I want miss this weekend .

Re: Losing prop blades
 

More damage :eek: :eek: . I got to checking out the rest of the drive and found the hinge pin sheard off .I had a Snap On screw extractor set and lucky me was able to get the broke screws out. The hp style that has the 2 10/32 screws that hold it on.Non sender type, I guess the vibration from the prop blade make it break :( Has anybody broke one of these ??

The new style has 4 - 1/4 screws holding them in.It must be a reason why they changed.

Rob

Re: Losing prop blades
 

when we lab or thin the bravo ones, at times not all air pockets pop up leaving a big hole which was there from the get go. :rolleyes: it sucks,we end up cutting the entire area out and fill with weld usually we don't have any problems in that area again.BOTTOM LINE IS, IT'S POOR CASTING AND QUALITY CONTROL.I have never had this happen to a mirage except one that was very thin running 700 plus hp.If the prop is not nicked or damaged ,Merc will replace it IN TIME.SO I have heard,also they are way out of balance and need to be balanced ,you may not feel the vibration ,but if there is a void and out of balance like they are and I see everyday,THEY WILL OPEN UP AND BREAK under tremendous stress from running.ALWAYS INSPECT YOUR PROPS AFTER EACH USE.

Re: Losing prop blades
 

i think glh has sheared his pins, not sure. you might want to pm him. stecz

Re: Losing prop blades
 

wait till you throw a blade off one of these, I thought the boat was going to come apart from the vibration.

Re: Losing prop blades
 

This weekend it happened again on the new prop. So that makes 3 that has done this . The crack is in the exact same place on the blades the others.Seems to happen when I run hard for about 10 minutes flat water. Its not hitting anything and I am not over trimming it.No nicks and not even any sand scratches.At least I caught this one before it chunked it :eek:any Ideas ?? This one I bought it in June of last year . Mercury said tuff sh*t.To buy more stock in Mercury :mad:

Re: Losing prop blades
 

This is the blade next to it. New crack about .325 long just started

Re: Losing prop blades
 

Re: Losing prop blades
 

This is the blade next to it. This is how it starts.

http://irev.net/strippoker388/prop%209-7-04%20003.jpg

Re: Losing prop blades
 

I think the "when you bought them" might be the issue. I chunked two last year in a span of two weeks...same spot as you. Merc warranteed BOTH. They told me and Pier 57 that they had a bad run of props and it is weird how mine both went on the same spot. I bought my current ones from Lake Cumberland and they have been fine. I thought my drive was screwed but they looked in it and just chalked it to the bad run of props.

Re: Losing prop blades
 

Happened to me too. Stock Bravo1, mine was two or three years old.

Re: Losing prop blades
 

I know... Merc issued a service bulletin this spring on Bravo props and inspecting them for cracks. Also, they do not warranty the props for the cracks!! Strange, huh?
My mechanic just filed a claim to Merc for two Bravo's 30" pitch for the same problem. We are waiting to see the results.

Re: Losing prop blades
 

usually on these props that are bad ,if you look real close you can see a round circle or bubble about1/8 in dia,this is where the void is, if you were to start grinding on it, you will end up with a large hole :rolleyes: :cool: ,.If it's cut back completly and filled with filler wire it will hold up .but this has been going on long before they said they had a bad run on the props ,it's another one of those deals ,

NOTHING IS PERFECT. We fix them all the time, also if you notice most of all of the cracks start at the trailing edge(the cupped area) if you look at all of the Bravo-ones where they grind the castings burrs off the edge leaving big belt lines in the blade setting them self's up for a crack to start ,if this were polished in this area it would be alot stronger ,yes stronger by polishing and greatly reducing the chances of failure. I also see alot of cavation burns on the prop blades even though it may look [polished to some,it's has been cavating and under TREMDOUS FATIGUE.

Re: Losing prop blades
 

This is a question for Bob Teague at Teague on Tech... He knows everything.... Right Strip?..... Strip?...... :rolleyes:

Re: Losing prop blades
 

I found this tread also.


http://www.speedwake.com/upload/show...334#post240334

Re: Losing prop blades
 

prop blade in the roost about half way up

Re: Losing prop blades
 

blade gone

Re: Losing prop blades
 

Hugetime might have a point...I've seen the same thing with Kaama drives...the slapping knocks a blade off. The balance thing could be an issue too. The Kaamas tended to be less likely to throw a blade on a 4 blade, probably a combo of less stress per blade, and better balance. Are your drives indexed? Maybe 2.75 isn't really 2.75? How would a quality 5 blade work for your set-up?