Mercury prop blade flies off while on plane

Sandy,
This appears to be a case of stress corrosion caused by an impact to the blade on the trailing edge. You can see where the damage started at the very edge (smooth and mechanically deformed) then granular propagation for the next inch or so then the stress fracture in the remaining root area. These are distinctive in the picture of your blade root area below. I suspect this blade was impacted then underwent a case of stress corrosion cracking and eventual failure. If you look at the root edge of the forward propeller blade, something also impacted that root area; it is mechanically deformed. Seems these blades do not have a lot of cross sectional area at the root; consequently, if I had them on my boat they would be pulled every time the boat was out of the water and looked at by someone qualified. I would also say that in looking at the other metallic structure in the picture that there may be some chloride stress corrosion cracking in other areas of the propeller; this is usually indicative of spider web looking cracks.

I'm also following the Back Cove/Sabre Facebook page referenced in post #41. The same guy just lost another prop blade this week and Mercury overnighted a replacement no questions asked and paid for haulout and labor. Something doesn't jive here.

quality time said:

I'm also following the Back Cove/Sabre Facebook page referenced in post #41. The same guy just lost another prop blade this week and Mercury overnighted a replacement no questions asked and paid for haulout and labor. Something doesn't jive here.

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Are you able to ask which series of Mercury props were involved with that other boat? Mine are the Z14. Thank you!

quality time said:

I'm also following the Back Cove/Sabre Facebook page referenced in post #41. The same guy just lost another prop blade this week and Mercury overnighted a replacement no questions asked and paid for haulout and labor. Something doesn't jive here.

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One more thing - year, make and model of the other boat and approximate hours if possible? If I can prove that they're taking care of Sabre owners and not Sea Ray owners with nearly identical drives then I will have a better case. All of the experts I've shown the prop to concur that it looks to be bad casting or corrosion related to our previous issues (that Mercury did pay for).

Here you go. I believe he had 580 hours when the first one failed a few months ago. No mention of current hours.

quality time said:

View attachment 61058 View attachment 61059 Here you go. I believe he had 580 hours when the first one failed a few months ago. No mention of current hours.

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Thank you very much!!

Read that BC thread today. Was thinking of you, Sandy.

Any updates?