MKMotorsport

Somehow managed to do this without hitting anything in the water (rudder and hull bottom don't show any signs of impacting anything). This prop had maybe 15-20 runs on it. It is a "cast" AL prop and was balanced correctly. Anyone ever seen this or had problems with the cast AL props that are now available from some vendors? In the last pic you can see what looks to be another crack forming to the right and below of the "75" stamp. Boat was running awesome prior to this letting loose with a BANG! [X(] Just glad it happened out on the water and not running next to me on the shore [X(] Bad prop/bad luck? or something more sinister like a driveline vibration problem?






MKM

martno1fan

It probably hit a bit of wood or a turtle ?.
Mart

Ron Olson

My Feedback: (1)

Nope, it's a cheap RMB prop probably from Warehouse Hobbies. This is one case of getting what you paid for.
I'm not a metallurgist but I can see how poorly it was cast.

MKMotorsport

The rudder dosen't have even the slightest ding or mark on it, neither does the running surface of the hull. The metal grain does look horrible in person. Didn't want to name any names about where it was from Thought I'd try one for the heck of it, seemed to hold up fine with a stock engine, but apparently didn't fare as well with the power output of a modded one. Any futher comments/flames welcome

NeoGenesis

My Feedback: (27)

Seeing how the cracks seem to stem from the hub....is it possibly that it's a cheap/soft casting combined with too much torque on the prop nut leading to the premature failure?

Just a thought,

Neo

MistralK

Cannot be vibrations of the strut and bad materials associated whit too much load?

Stephen

Justaddwata

My Feedback: (3)

Look on the bright side - now you have a good excuse to buy yourself a new one . If that prop worked well for you you might consider going with a 275 in stainless. Probably the same prop and you wont break a stainless prop like you have the al one.

Dan S

all good advice.

Stay away from aluminum and go with a BC or SS prop.

Dan.

BMAD01

Even the high $$$ props have their days.[&o] Get another one, but get it from a reputable prop guy like Dasboata. It will be balanced and polished and sharp! That prop looks like it came out of the package with nothing ever done to it.[] It was probably out of balance, but you can not predict what your going to hit below the water surface that will take out the best props. Brian

pedro2-5

hey mate had the same thing happen to me i dont use ally anymore

munro1656

I used to run alloy props but no longer due to how easy there are to be damaged

MKMotorsport

Thanks for the replys, seems im not alone with the issues with the AL props. Lesson learned, I'll stay away from them. I think my next gas boat related purchases need to be some decent props, from a prop guy that knows which end is up Because that certainly isn't me at this point!

Thanks,
MKM

Ron Olson

My Feedback: (1)

They're not the only ones that they can hapen to as even good brand-name props have been known to throw a blade. Most come from overthinning a prop than not heat-treating them aftewards. One brand, it may have been ABC but don't hold me to it, had a bad batch of gas boat props that was in one size only that they replaced free of charge.
The scary thing about this is that the prop could have just as easily broken while trying to start the engine and done some personal injury.
To me, in the shot at the beiginning I'd say that the aluminum may not have been in a fully molten state when it was poured/injected into the mold. If you got it from Tony, you might want to let him know.

martno1fan

That prop did look bad quality ,that said ive been using one in a boat for a year (ali prop)with stock zen and no probs so far.I think theyre ok for the money but i dont think id run one on a full mod ,i tried modding one and snapped the blade so i know how easy they can be to damage .
Mart