Metal erosion
 

I have a 43 Black Thunder with labbed 24 Bravo 1's. They had a nice polished finish but slowly the starboard one seems to be eroding. It's on the leading edge of the blade about halfway across. The port prop is still nicely polished. What causes this and do I have to worry about the prop coming appart?

Re: Metal erosion
 

prop burn? passing air bubbles over prop surface.happens over 50 mph?..........m.m..........

Re: Metal erosion
 

Yo're over 50 a lot Mark, is that something that's common?

Re: Metal erosion
 

but i dont have prop burn!!!!!!!!!!!m.m.......

Re: Metal erosion
 

Cavitation burn can be caused by a variety of reasons.

What it actually is though is a pressure differential on the high pressure side of the blade causing the water to boil. The turbulence is violent and burns the metal away.

24 Bravo1's aren't known to have a geometry to induce this. Your situation would be caused by drive height, hull configuration, transducers, etc. causing aerated water to attack the face of the blade.

It is possible to have a casting with extensive porosity which may accelerate the process.

Re: Metal erosion
 

would the boiling create air bubbles?...m.m...

Re: Metal erosion
 

The pressure change cause the boiling which is the bubbles.

Re: Metal erosion
 

thank you............mark...........

Re: Metal erosion
 

If you could post a picture, we could possibly determine whether you are experiencing cavitation burns and not an environmental issue such as oxidation or electrolysis.

Julie

Re: Metal erosion
 

Thanks for the replies. I'll try to post a pic tonight.

Re: Metal erosion
 

Here are the pics.

Re: Metal erosion
 

Can you email the photo to me I cannot quite tell from the photo you have posted. Is it pitting or does it appear to just be on the surface?

Julie

Re: Metal erosion
 

It is several thousanth's deep. Lines are forming and they are getting longer and deeper. I'll try to get Donna to e-mail them. I'm at work and they are on home puter. Thanks.

Re: Metal erosion
 

I just them to you Juile

Re: Metal erosion
 

This does not appear to be cavitation burn.

First, it is on the low pressure side of the blade. Cav. burn happens on the face or high pressure side of the blade.

It looks to be build up rather than pitting. Lake Erie has the water make up to causes this type of mineral build up on propellers all the time.

Re: Metal erosion
 

If it is a mineral buil-up, it is very metallic looking. I tried to sand it smooth once with 280 grit wet sandpaper. Didn't work. Too hard. And it is only this prop. The port prop is still shiny. Not arguing just trying to give as much info as possible. Thanks.

Re: Metal erosion
 

If its just build up on the prop try Lime Away. Dont sand your prop what ever you do. Hard water stains will come right off with non abrasive Lime Away. Dont sand it, steel wool it, scrub with a scouring pad, anything abrasive will ruin the finish.

Re: Metal erosion
 

I used acid based mag wheel cleener on the prop before taking the picture, just to clean it up. No sign of calcium. Steel wool won't touch this.