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Hairline crack in prop blade - what the ?

Old 09-16-2002, 08:26 PM
Uncle Toys
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Default Hairline crack in prop blade - what the ?

Took the boat in this Saturday to have the oil changed and found a hairline crack half-way through one of the blades on the port-side prop. Mechanic strongly recommended not using that prop and I agreed. So B.O.A.T. for another set of props (old ones were too big anyways).

Anyone else run into something like this? There were absolutely no burrs on the edges of the blades and I canít remember hitting anything. Iím really puzzled
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Old 09-16-2002, 08:37 PM
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let me guess...................bravo ones?
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Old 09-16-2002, 08:45 PM
Join Date: Oct 2000
Location: Greenwich CT. U S of A
My Boats: 38' Cigarette, 42'Post, Driver:F2-07 Wild Child
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I bet they are Hydromotive??
I have cracked a few blades & have heard of many others.
No dings, no hits, just a plain old stress crack
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Old 09-16-2002, 09:11 PM
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Location: Houston, TX, USA
My Boats: 2003 Eliminator 30' Daytona
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UT- Thought we had problems. Have you read elimi's story about his year of boating.

Looking at buddies 28 daytona lab finshed props one day & found blade with small crack. He & I checked around & we were told that with 130 hrs on lab finished prop he was lucky it made it that long. Talked to local prop guy & charged him close to $300 (new stock bravo was 500) repair. (70 of that was to polish it) Prop lasted for 2 weekends before it slung the blade. I guess lucky no one got hurt.

I was having second thoughts about getting my prop labed after that & now I learn this week or last, that when you lab a prop you loose midrange cruise rpm. I guess I am going to save my $ & stick with my stock 30. Maybe will be missing a mile or 2 but I do more crusing @ 3k & below that I do at WOT.

I guess this will postpone/cancel the motor rework since new props are in order.
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Old 09-16-2002, 09:32 PM
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Tell us what brand of props they are?
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Old 09-16-2002, 09:43 PM
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This happens more frequently than what most of would think. I remember being at a professional high performance prop shop one time and seeing dozens of cracked blades. It's my theory that this happens most frequently on props that are surfacing. When the blade is in the water it is loaded and leans back. When the blade come out of the water it is suddenly unloaded and springs forward only to get slammed back into the water. I believe that it was this flexing that work hardened my Hydromotive prop and resulted in it's failure with in hours.
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Old 09-16-2002, 09:44 PM
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ut jana has a cracked hydo if you have them labbed that is what they do they thin the blads and they can not take it but it sounds like they got it too thin
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Old 09-16-2002, 10:10 PM
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I threw a blade on a Mach prop this summer. Looking at the break which happened at the hub there was evidence a very fine crack had been there.
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Old 09-16-2002, 10:17 PM
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Had to have Merc. warranty one about a month ago. Blade developed a stress fracture on the back of one blade, no impact marks whatsoever! Just had finished a great run and was wiping it down when my son said "Dad, your prop's broke!" Absolutely ruined my day!

Last edited by RedWarlock; 09-16-2002 at 10:21 PM.
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Old 09-16-2002, 11:16 PM
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Feel for you, it seems like when it rains it pours, I had the same thing happen on a mirageplus23, found the crack and replaced it before it let loose, at least you caught it before it broke!
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