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Old 01-07-2016, 09:34 AM   #21
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From what I've been told over my years in power pleasure boating... there is nothing wrong with relatively sharp edges "eventually" becoming present on an older prop as long as the metal has not been attacked by material-debilitating electric currents.

IMO, short of going through fairly expensive prop reconditioning procedures, if the boats engines are still moving boat at established speeds (per rpm used), and, there is no unusual vibration compared to previous experience... then the props are probably in fine condition.

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Old 01-07-2016, 09:36 AM   #22
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Originally Posted by WesK View Post

When I had a small I/O, I could swap props at will for testing. Not with this boat. can. There are divers that will dive on your boat and change props...around here they go for about $100....that is taking it off AND putting it back 2 dives. There is a crazy guy around here that does it without tanks....I have seen him change a prop without tanks. Crazy Steve I think we call him. Anyway, while chucking $100 is not all that is easy....and you can compare props "relatively" cheaply.

Prairie 29...Perkins 4236...Sold
Mainship Pilot 30...Yanmar 4LHA-STP...Sold
Carver 356...T-Cummins 330B
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Old 01-07-2016, 01:00 PM   #23
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Originally Posted by WesK View Post
"take it to a reputable prop shop"

That can be a problem. How do you decide which shop is "reputable"?
That is probably one of the most relevant questions asked on this forum. I can only tell you what we do. Over the years my wife and I have built up relationships with people in or connected to the marine and aviation industries in this area. I include aviation because a lot of these people are also involved in boats and boating. We have also met in the course of our boating a number of people who are really, really knowledgeable about boats or who have businesses that use or rely on one or more boats.

So when a question arises, be it about props or the situation that's being bandied about in the thread called "La Perouse," these are the people we turn to.

For example in the months-long troubleshoot and repair process we recently went through with the yard in our harbor, I called a good friend who's entire career has been in the field that includes the problems we were encountering, relaying what the yard was doing or recommending and getting his opinion on the validity of each action or recommendation. The fact that he concurred with everything the yard was doing and also made some suggestions I relayed to the yard which they were happy to receive and act on went a long way toward allaying our concerns

So part one of my answer is search out people who truly know what they're talking about. In the case of finding a good prop shop we asked a friend who at the time operated of a barge (landing craft) service in the San Juan Islands who had had major prop work done on his LCM-6 and who is a genius at mechanical things in his own right. We also asked the friend I mentioned in the previous paragraph who until his recent retirement was the head of the engineering department at one of the industry's most respected propulsion and generator manufacturer, Northern Lights/Lugger, who we had come to know through our floatplane flying.

Both of these people independently gave us the name of the same shop in Seattle so this and other similar recommendations prompted us to contact them.

Part two of my answer is more challenging I think. One simply has to be a good judge of character and instinctively know when a person one is talking to is credible or not.

Obviously we live in an area where these kinds of resources are readily available. The boating community is huge here with every imaginable size and type of shipyard, engine shop, prop shop, etc.

In a smaller community or one not as heavily involved with the maritime world it can be harder to search these people out. An owners internet forum for the type of boat one has can be a help. The Grand Banks owners forum has several members with impressive credentials, one of whom operated a boatyard specializing in GBs in this area for many years. So I have in the past corresponded with him on various questions either directly or via the GB forum and he has recommended courses of action or directed me to professionals he knows in the industry.

Don't know that this has helped much, but it's our approach to answering your question.
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Old 01-14-2016, 08:03 PM   #24
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City: Punta Gorda, fl
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Vessel Model: Nordic Tug 37 2002
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Originally Posted by manyboats View Post
My best performing prop is like that. Thin and a tad pink. Bought a new prop but I'd really like to have the old one back on. Since we run less than 40hp (16 - 18 at cruise) the old one was probably fine but throwing a blade would be a shakey experience. But the new one has a tad too much pitch and next time i'm out I'll have some blade edge ground off.

A bronze prop turning pink is a mark of a failing bonding system and/or under protection by anodes recheck the system and consider adding more anode material nearby
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Old 01-14-2016, 08:26 PM   #25
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the name of the same shop in Seattle so this and other similar recommendations prompted us to contact them.

Well, go on, I'm holding my breath here!
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Old 01-15-2016, 08:19 AM   #26
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The marina manager and a couple other boaters seem to think that the prop that's on the boat is fine and I've had no issues with it so I'm just going to leave things as they are and put the spare away for a spare.

It's that "If it's not broke, don't fix it." situation.

Thanks for the responses and suggestions.

After way too long for the work that was done, the boat will be back in the water on Monday.
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Old 01-15-2016, 10:19 AM   #27
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If it's a corrosion issue it won't be uniform, a "knife edge" unless it's serrated, isn't the result of corrosion. Also, unless its stray current corrosion, it will almost certainly be dezincification, which manganese props are subject to, and in that case the corrosion areas would be pink.

I suspect this is how the prop was finished when last reconditioned, in an attempt perhaps to eliminate singing (an anti-sing edge is typically more chisel-shaped). I occasionally encounter very sharp trailing edges, it's not an issue per se as long as performance is correct, i.e. no cavitation and the engine turns up to the rated wide open throttle rpm.

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