Prop Wear
- Thread starter rwidman
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If you have answers, please help by responding to the unanswered posts.
Nomad Willy
Guru
Do you have prop singing?
Not that I know of.
I am not the original owner so I don't know the answer. The original owners put 2800 hours on the boat cruising the US east coast.
The boat is a 2000 and I have owned it since 2008. In the pre-purchase survey, the surveyor commented that the edges (of the prop) were "thin due to electrolysis".
The boat came with an extra prop. The writing on the box leads me to believe that this spare has been reconditioned or reworked. I've thought about exchanging the two but there's no point unless the one that's on the boat is less efficient than it could be.
The boat is out of the water being bottom painted so now would be the time if I'm going to do it.
The boat is a 2000 and I have owned it since 2008. In the pre-purchase survey, the surveyor commented that the edges (of the prop) were "thin due to electrolysis".
The boat came with an extra prop. The writing on the box leads me to believe that this spare has been reconditioned or reworked. I've thought about exchanging the two but there's no point unless the one that's on the boat is less efficient than it could be.
The boat is out of the water being bottom painted so now would be the time if I'm going to do it.
A knife edge trailing edge is almost certainly due to corrosion. That corrosion makes the entire prop blade weak. If it is driven by a low power engine then you shouldn't be in much danger of throwing a blade. But if you have a couple of hundred hp and you sometimes use it....
David
David
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Urine tournament...
eyschulman
Guru
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Corrosion very suspect when you replace props and you may well have to make sure the new props don't go the way of the old. Check for stay electricity your boat dock or neighbor-keep active zincs proper # and size-check to see if shaft needs grounding. If you are not comfortable with this stuff get a professional to check it out props are expensive as you will soon know.
eyschulman
Guru
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Yes something should be done about that. Certainly if there is a realistic definition all the second poster would have to do is display it for all to see. Don't you think that on a form called Trawler Form where people sometimes talk about a "Trawler" there should exist a definition of what the thing is? Actually there has been little arguing about the definition since hardly a word trying to define the term has been said. It is not unusual for specific topics to get higher response look at the anchoring posts. Here where we are talking props which are very important since that is what makes a boat go there may only be moderate interest. Props may not be a emotionally charged subject.
Nomad Willy
Guru
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.
I went down earlier today and got the spare out of the lazzarette. To the untrained eye, there's little difference. It was cold and windy and I've had a very bad cold so I didn't spend a lot of time comparing the two.
I called a local prop shop but they declined to visit the boat and give advice or change the prop. They only repair them, they don't install or remove them.
The boat looks like it will be out of the water for a few more days so I'll go back and check a little more.
I called a local prop shop but they declined to visit the boat and give advice or change the prop. They only repair them, they don't install or remove them.
The boat looks like it will be out of the water for a few more days so I'll go back and check a little more.
FWIW, some years ago during a routine haulout it was discovered that we needed a cutless bearing replaced on one of the shafts. Since the shaft had to be pulled to do this the yard went ahead and sent the shaft and its prop to the shop they use for evaluating these components. Turned out the shaft was slightly bent so they straightened it and installed a far more robust coupler than the original.
When they looked at the prop (a Michigan) they said it had been "worn down" and needed to be replaced. The evidence, according to them, was that the trailing edges were very sharp. There was no corrosion, galvanic or otherwise, on the prop.
They said that over time the surface of a prop can be worn down particularly if the boat is operated in water that has a lot of particulates suspended in it. The boat had spent the first 25 years of its life in SFO Bay before we bought it and trucked it north, much of it in the delta and river area which we assumed could be pretty muddy at times. We were skeptical of the shop's explanation but at the time knew very little about this stuff so it seemed more or less plausible.
The other prop was in the same condition as the one the shop looked at. The yard manager said he didn't think we needed to take any action at the moment so the shaft and prop were replaced and we boated for another season or so.
Fast forward to the following year when we decided to pursue the notion of replacing the props. Research had showed us that the best prop shop in the area was not the one that had examined our prop before, so we took both props to the shop that had been highly recommended by friends in the marine industry. We called this shop first and they told us the kind of performance information they needed to determine the best props for our specific boat.
We obtained the information and a few weeks later walked in with our two props fully expecting to have to buy new ones, which would have at the time cost about $2,000 each.
The fellow who received us when we walked into the shop took one of our props and went into the shop to check it. When he came back he said our props were physically just fine but they had been horribly set up by whoever did it last, which would have been someone in the SFO Bay area.
So insead of buying new props we had the ones that came with the boat completely reconditioned, tuned, and balanced for about $350 each as I recall. This included smoothing and rounding off the sharp trailing edges.
These props (four blade) are still on the boat 17+ years after we bought it and probably some 10 or 12 years after the prop shop reworked them. The sharp trailing edges have never reappeared.
So I would suggest that someone with a questionable prop take it to a reputable prop shop-- there seem to be plenty of the other kind--- and have it evaluated by people who know what they're doing. Sharp trailing edges can be the result of several things, it seems, but what we learned is that it does NOT automatically indicate a fundamental problem with the prop that would require its replacement.
When they looked at the prop (a Michigan) they said it had been "worn down" and needed to be replaced. The evidence, according to them, was that the trailing edges were very sharp. There was no corrosion, galvanic or otherwise, on the prop.
They said that over time the surface of a prop can be worn down particularly if the boat is operated in water that has a lot of particulates suspended in it. The boat had spent the first 25 years of its life in SFO Bay before we bought it and trucked it north, much of it in the delta and river area which we assumed could be pretty muddy at times. We were skeptical of the shop's explanation but at the time knew very little about this stuff so it seemed more or less plausible.
The other prop was in the same condition as the one the shop looked at. The yard manager said he didn't think we needed to take any action at the moment so the shaft and prop were replaced and we boated for another season or so.
Fast forward to the following year when we decided to pursue the notion of replacing the props. Research had showed us that the best prop shop in the area was not the one that had examined our prop before, so we took both props to the shop that had been highly recommended by friends in the marine industry. We called this shop first and they told us the kind of performance information they needed to determine the best props for our specific boat.
We obtained the information and a few weeks later walked in with our two props fully expecting to have to buy new ones, which would have at the time cost about $2,000 each.
The fellow who received us when we walked into the shop took one of our props and went into the shop to check it. When he came back he said our props were physically just fine but they had been horribly set up by whoever did it last, which would have been someone in the SFO Bay area.
So insead of buying new props we had the ones that came with the boat completely reconditioned, tuned, and balanced for about $350 each as I recall. This included smoothing and rounding off the sharp trailing edges.
These props (four blade) are still on the boat 17+ years after we bought it and probably some 10 or 12 years after the prop shop reworked them. The sharp trailing edges have never reappeared.
So I would suggest that someone with a questionable prop take it to a reputable prop shop-- there seem to be plenty of the other kind--- and have it evaluated by people who know what they're doing. Sharp trailing edges can be the result of several things, it seems, but what we learned is that it does NOT automatically indicate a fundamental problem with the prop that would require its replacement.
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I guess you will have to ask around. There are only two in the Houston area(Baumann and Hood). And this is an area that has a huge recreational boating population and an even hugER commercial boating population to support the oil industry.
I am with Marin here. I have seen these guys perform miracles. The boat I have now I had to buy a new prop because one fell off because the shaft broke!!! Yeah, you heard that right. The electrolytic corrosion was so bad that the shaft broke in half during the sea trial. Imagine what the props looked like. They were literally half gone and beat to hell. Well I had to buy the one because it had departed. But they managed to revive the other one. I do not know how they ADD metal to the prop but that is the only way that they could have don it. They must weld it on and then machine it back down. All I am saying here is that even if there is metal that is missing from the prop, it can be added back to it. I have no clue how....but they did it in this case.
There are no other prop shops in this area that I know of. These guys do amazing work. It is not uncommon for people to ship their props out of town for work. You may look into that. You can also call Hood Propellor in Houston and talk to the owner himself(Mike Hood) or his wife. At the very least they can give you an idea of what you are in for and maybe they will be able to direct you to a reputable shop in your area.
psneeld
Guru
Knife edges on the assistance boat prop every year. NO corrosion issue.
EROSION issue from sand, mud and sediment was my problem.
Hopefully no recreational boat is trudging through the same soup as what I used to do...but in a high sediment area and enough years...sure the edges can sharpen up is my best guess having done so repeatedly for years.
Could it be something else? Sure... but if it is perfectly smooth like it was ground to an edge and not significantly discolored pink......I will vote erosion.
When back from the reconditioning place...they would just grind a tiny, flat trailing edge and no issues. As long as the metal is good, a shop can add back if there is more than a little worn off.
EROSION issue from sand, mud and sediment was my problem.
Hopefully no recreational boat is trudging through the same soup as what I used to do...but in a high sediment area and enough years...sure the edges can sharpen up is my best guess having done so repeatedly for years.
Could it be something else? Sure... but if it is perfectly smooth like it was ground to an edge and not significantly discolored pink......I will vote erosion.
When back from the reconditioning place...they would just grind a tiny, flat trailing edge and no issues. As long as the metal is good, a shop can add back if there is more than a little worn off.
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I looked at both Baumann and Hood websites. They both mention they are members of the National Marine Propeller Association. Maybe that would be a start as to finding a reputable shop.
National Marine Propeller Association
National Marine Propeller Association
psneeld
Guru
Not sure who determines which shop is good or bad.
The one often used where I am is a father and son working out of a residential garage.
They have the latest in computer measuring even though when you walk in it remids you of a 1950s one bay auto repair shop where the old guy in overalls wiping his hands with a red bandana walks up to you.
the props are mostly still just hammered back into shape as far as I have been told so don't think anything more sophisticated than a hammer and pitch block is being used no mattter where you go.
And like doctors...a little research and a second opinion if the first sounds out of place.
The one often used where I am is a father and son working out of a residential garage.
They have the latest in computer measuring even though when you walk in it remids you of a 1950s one bay auto repair shop where the old guy in overalls wiping his hands with a red bandana walks up to you.
the props are mostly still just hammered back into shape as far as I have been told so don't think anything more sophisticated than a hammer and pitch block is being used no mattter where you go.
And like doctors...a little research and a second opinion if the first sounds out of place.
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I mentioned that I have a "spare" prop that was on the boat when I bought it. This spare seems to have been worked on by a shop (the box indicates a shop in Norfolk, VA but I have no proof that the prop and box go together).
My guess is that the PO damaged the original prop while cruising, bought another and had the original repaired and kept it as a spare. That's just a guess. I may call him if he is still around and ask.
What I can do is try to compare the two as best I can with a tape measure and a micrometer. I've had no issues that could be traced to the prop but of course wear would mean a gradual loss of efficiency.
When I had a small I/O, I could swap props at will for testing. Not with this boat.
My guess is that the PO damaged the original prop while cruising, bought another and had the original repaired and kept it as a spare. That's just a guess. I may call him if he is still around and ask.
What I can do is try to compare the two as best I can with a tape measure and a micrometer. I've had no issues that could be traced to the prop but of course wear would mean a gradual loss of efficiency.
When I had a small I/O, I could swap props at will for testing. Not with this boat.
psneeld
Guru
If all you have is a sharp edge...probably not much loss in efficiency...
I am guessing the reason they are usually a little thicker and flat is just so they aren't easily damages where even small variations would start causing vibes and loss of efficiency.
If you can call that prop shop or check in the boats papers if any, they may have a copy of the final computer readout of that spare prop. That way if you put it on and you notice anything different, you/the shop can compare it to the prop you are taking them and adjust if necessary.
I am guessing the reason they are usually a little thicker and flat is just so they aren't easily damages where even small variations would start causing vibes and loss of efficiency.
If you can call that prop shop or check in the boats papers if any, they may have a copy of the final computer readout of that spare prop. That way if you put it on and you notice anything different, you/the shop can compare it to the prop you are taking them and adjust if necessary.
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.
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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Well....you 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 on....so 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 cheap....it is easy....and you can compare props "relatively" cheaply.
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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Pgitug
Guru
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
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.
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.
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.
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.
