edb07

Gone through 6 BravoThree rear propellers. One in less than 2 hours hard run time. The rear, especially on the port side of a Formula 400SS with 415/502s (upgraded exhaust).

Both drives replaced on a Mercury Warranty upgrade in February 03 (3Xs) and that did not resolve the problem. The first two props were older style, the last 4 were all the newer HD castings. Mercury has warrantied 3 and awaiting credit on the 4th. I run them hard and they get some cavitation then crack. See attached photo showing pre crack condition. Mercury does not appear to have an explanation and does not acknowledge any other people having this problem.

Any suggestions or help on this issue appreciated. (HoustonProp come in).

Ed

zahndok

I was told by my prop shop,(Bronson Hill) that my cracked bravo 1 32 was likely from overtrimming. He pointed to the cavitation marks and their relative position on the blades to support his case. I had him place as much tip cupping for bow lift in the new prop and now attempt to run with less trim although the boat likes the trim. I was told that Merc wouldn't warranty the cracked blade even if it hadn't been labbed.

edb07

I thought about the trim issue and ran the boat glued in when the last two cracked. The cracking sometimes occurs before the cavitation damage appears.

HOUSTONPROP

I have not seen this before on this set-up,the cavation burns ????

this is caused by a disturbance of some type or another? nicked edge. Blunt edge not rounded ,a sharp edge will cause this,or flow not direct to the propellers b(bottom of boat)//??????

THE CRACKING I HAVE SEEN AND KNOW THEY ARE BRITTLE.

WHY NOT SURE.

THE WAY TO GET TO A TRUE HONEST ANSWER IS TO SEND THE CRACKED PROPS AND A BRAND NEW PROP to a METALOGIST?SPELLING,

THEY WILL COME UP WITH THE ANSWER IT WOULD COST SOME BUCKS TO HAVE THIS DONE BUT they would have the real answer.casting issues.or whatever?

WE WORK ON GAS TURBINE BUCKET'S(BLADES) AND SEGMENTS AS WELL and know some people in the Turbine indusrty that you could send them to.rotate the prop take a picture down the( EDGE) So we can see it better.Darin I can weld and stop the crack,but let look at some more pictures

HOUSTONPROP

also what shape is the skeg in ,nicks ect and if aI remember,I have seen new props that the leadind edges's are somewhat beveled,from the way the casting was made,poor design ,this would cause the cavation burns, and cupping they are not supposed to be cupped at all either prop.on this set-up.

HOUSTONPROP

the cracking is something to due with the tensile strength,it's to brittle,they were not cooled properly.

This would be like taking a stainless prop heating it red hot and throwing it in a bucket of water to cool it down.

big mistake,after that you hit it with aHammer and it will shatter like glass,I have seen prop shops do this,not good it ruins the prop for life.JUST SO THEY CAN KEEP WORKING ON IT FASTER ,INSTEAD OF rotating the work and let it cool properly by air at room temperature.

HOUSTONPROP

also look at the discolorations of the prop looks like rust ,in the hub barrel inside and surface of prop lightly,this is because the prop has a very high CARBON CONTENT, STEEL; NOT STAINLESS

MAGNETS ARE NOT SUPPOSED-TO STICK TO TRUE STAINLESS TAKE A MAGNETIC Business card throw it on the prop or any prop and it will stick,find something that you know is stainless and watch the magnet will not stick,it's just the way it is but they should hold up ,if not they should be replaced,sorry you are having such a bad time with this and I am sure it's very frustrating.

US1 Fountain

iTrader: (1)

That is one rusty prop. (Added some light to see better)

HOUSTONPROP

you did that,??But ThankYou!

this show's the high carbon content in these props , it's terrible when you pay that kind of money and get something like that.

Thanks US1FOUNTAIN,for putting a little light on the subject.

Darin

edb07

Thanks for the pic enhancement, also! I’ll take pics of existing props. Rust is prevelant on both and cavitation burn present on port (Its too cold to run hard now). I do not think that the forward props rust as bad as the newer style rear props but they do rust. Wilmington Propeller, where I took the first two to be repaired, said forget it because of casting problems and high carbon content. Advised by Mercury rep. that problem was solved by new castings "B" (See Photo). Obviously did not fix problem.

“Scott” at Mercury is supposedly working on the issue but as yet he has never contacted me. I just keep returning props and get new ones or credit. Seems they would want to resolve the problem also. I feel sorry for those who do not have lifts and have to wait tell it gets real bad before discovering the problem; by them the props are usually out of warraty period or so bad that it is impossible to determine if crack caused by strike or too much carbon.

Anybody out there know “Scott” from Mercury in the Warranty, Technical, or Customer Support Section?