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  #11  
Old 06-29-2006, 01:04 PM
TMCNo1 TMCNo1 is offline
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No picture, but it looks like someone has sandblasted a spot on the starboard side of the rudder about 1.5" in dia. about 1.5" down from the top of the rudder, with coarse sand and spots can occur in the thick meaty part of the prop blade close to the hub on the rudder side of the blade about the same size. The prop spots are really noticable on OB or I/O aluminum props, where it has eat away the black factory paint, more so from cavatation than electrolysis.
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Last edited by TMCNo1; 06-29-2006 at 01:08 PM.
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  #12  
Old 06-29-2006, 03:07 PM
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jeverett jeverett is offline
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Sounds to me like someone tryied to put some pull in the steering by grinding said rudder on the right side and didn't know what the HE#@ they were doing?????
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  #13  
Old 06-29-2006, 03:53 PM
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Hoff1 Hoff1 is offline
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my rudder on my 1990 shows some cavitation signs with the pits in it. Prop is original, don't have a clue if it's sized right, or if it causes excessive vibration, or noise or caviation. But it keeps me going.

Probably should upgrade, but just cheap and lazy I guess.
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  #14  
Old 06-30-2006, 09:15 AM
viabill viabill is offline
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Here are a few pics of this rudder erosion. It looks just like TMCNo1 described.

You can't really see it, but in one place, you can see light from one side through to the other side.

Last edited by viabill; 04-05-2007 at 09:32 PM.
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  #15  
Old 06-30-2006, 10:11 AM
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SkiDog SkiDog is offline
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Quote:
Originally Posted by TMCNo1
In other words, the boat maker may have several reasons for not being able to put the correct prop on the boat - mostly, I suspect that they can't afford to test and have a prop custom made for every boat model they make - they have to take what's available.

You should see the pallets of experimental props in boxes that Mastercraft has built up over the years, that MC has had made special for all the boats they have built. The prop manufacturers are always working with boat builders in this manner for their business. The R&D department is always trying out new ideas and combinations to provide the best all around performance in the boats they design for sale. The most amazing thing is, most if not all of these props that were not acceptable for use are then sold to a scrap dealer or given back to the prop manufacturer to melt down and recycle into other props.

Why do OB's and I/O's have sacrifical zinc anodes on the engines and lower units? Electrolysis! Why do most inboards other than salt water boats not have them. Any boat powered by a engine using electrical current as part of its function releases static electricity into the water to ground while running and this causes the softest metal in the water that has a direct ground to the engine to eat away at that metal. In OB's and I/O's the softest metal in the water is the engine or outdrive of aluminum, therefore a softer metal to be exposed is the sacrifical zinc anodes that they install on the transom and on the adjustable tab above the prop and have to be replaced over time. On an inboard the softest metal with a direct ground to the engine is the prop, which in turn discharges the static electricity to the rudder thru the water and then into the water causing the rudder to burn or eat away because it is softer [brass] than the prop [nickel/brass/aluminum alloy] or S/S which is harder. You may even see some erosion of the prop blades near the hub, but that is usually caused by cavatation and maybe some very small amount of electrolysis. The strut does not erode because it is isolated from the shaft by the bushings plastic surfaces and even though the steering cable is attached to the strut it is not attached directly to the electrical system via a ground. The New Saltwater Series boats that MasterCraft builds has sacraficial zinc anodes on the S/S Swim platform brackets and the shafts because salt water has a higher erosion factor because of the salt and electrolysis.
This was explained to me by a Mercury/Mercruiser engineeer several years ago at a boat show and in numerous article in magazines published throughout the marine industry.[/quote]

Harold, I didn't know you knew so many BIG words!!!!!!!
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  #16  
Old 06-30-2006, 10:42 AM
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Hoff1 Hoff1 is offline
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Quote:
Originally Posted by viabill
Here are a few pics of this rudder erosion. It looks just like TMCNo1 described.

You can't really see it, but in one place, you can see light from one side through to the other side.

My rudder has pits similar to the 3rd picture, but nothing as severe as the 1st picture. I have about 700 hours on mine for reference. Yours only having that amount in less than 300 hours does seem severe.
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  #17  
Old 06-30-2006, 11:01 AM
TMCNo1 TMCNo1 is offline
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Quote:
Originally Posted by skidog
You should see the pallets of experimental props in boxes that Mastercraft has built up over the years, that MC has had made special for all the boats they have built. The prop manufacturers are always working with boat builders in this manner for their business. The R&D department is always trying out new ideas and combinations to provide the best all around performance in the boats they design for sale. The most amazing thing is, most if not all of these props that were not acceptable for use are then sold to a scrap dealer or given back to the prop manufacturer to melt down and recycle into other props.

Why do OB's and I/O's have sacrifical zinc anodes on the engines and lower units? Electrolysis! Why do most inboards other than salt water boats not have them. Any boat powered by a engine using electrical current as part of its function releases static electricity into the water to ground while running and this causes the softest metal in the water that has a direct ground to the engine to eat away at that metal. In OB's and I/O's the softest metal in the water is the engine or outdrive of aluminum, therefore a softer metal to be exposed is the sacrifical zinc anodes that they install on the transom and on the adjustable tab above the prop and have to be replaced over time. On an inboard the softest metal with a direct ground to the engine is the prop, which in turn discharges the static electricity to the rudder thru the water and then into the water causing the rudder to burn or eat away because it is softer [brass] than the prop [nickel/brass/aluminum alloy] or S/S which is harder. You may even see some erosion of the prop blades near the hub, but that is usually caused by cavatation and maybe some very small amount of electrolysis. The strut does not erode because it is isolated from the shaft by the bushings plastic surfaces and even though the steering cable is attached to the strut it is not attached directly to the electrical system via a ground. The New Saltwater Series boats that MasterCraft builds has sacraficial zinc anodes on the S/S Swim platform brackets and the shafts because salt water has a higher erosion factor because of the salt and electrolysis.
This was explained to me by a Mercury/Mercruiser engineeer several years ago at a boat show and in numerous article in magazines published throughout the marine industry.
Harold, I didn't know you knew so many BIG words!!!!!!![/quote]


I'm not as good as I once wuz, but I'm as good once as I ever wuz!
Like you Skidog, there are somethangs you just don't ferget!
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Quote: 2RLAKE,
At some point in time people need to wake up, remove their cranial intrusion into their own rectal areas, and take responsibility for their own actions.




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  #18  
Old 06-30-2006, 11:14 AM
TMCNo1 TMCNo1 is offline
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Quote:
Originally Posted by viabill
Here are a few pics of this rudder erosion. It looks just like TMCNo1 described.

You can't really see it, but in one place, you can see light from one side through to the other side.
Dude, get that rudder replaced!!!!!!!!!!!!!!!!
I've never seen erosion that bad before and does look like a cavitation problem, especially on the back starboard side of the rudder behind the thick part. My original rudder eroded like that on the front starboard side, but only after I ran a polished and chromed 3 blade for 8 years. The original factory finish or polished prop did not erode the rudder. The port side looks like casting imperfections that weren't ground away when the rudder was made, as original rudder had marks like that new and it took forever to grind them out to polish the rudder.
My original rudder cracked 2 years ago about 1.5": down from the top on the starboard side in the thick part where the S/S shaft is cast into the bronze blade. I guess too much grinding and polishing in that area where the erosion was occuring, so I wasted no time in replacing the rudder!
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Quote: 2RLAKE,
At some point in time people need to wake up, remove their cranial intrusion into their own rectal areas, and take responsibility for their own actions.





Last edited by TMCNo1; 06-30-2006 at 11:19 AM.
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  #19  
Old 06-30-2006, 01:21 PM
viabill viabill is offline
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TMCNo1
I agree. In fact, I had ordered a new one and I picked it up today. I thought about smoothing it out, since they are pretty rough with lots of heavy grind marks as they come from the MC dealer. Will smoothing it out help to minimize the erosion?

I'm still really interrested in talking to someone who has experience with the Barefoot 190 to see how much erosion they have seen over the years. and if they changed props to help the situation.

viaBill
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  #20  
Old 06-30-2006, 01:26 PM
TMCNo1 TMCNo1 is offline
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Quote:
Originally Posted by viabill
TMCNo1
I agree. In fact, I had ordered a new one and I picked it up today. I thought about smoothing it out, since they are pretty rough with lots of heavy grind marks as they come from the MC dealer. Will smoothing it out help to minimize the erosion?

viaBill
Good call on the new rudder!
No, slicking up the rudder and even polishing it won't help prevent the burn, but it sure makes it PURRDY!!!!!!!!!!!!
Is the prop that you have on there now, the same one you have always run or is it fairly new. Looks like a S/S. That kind of burn and damage on a rudder takes several hard years of use to show up. If erosion or burn starts appearing on the new rudder real soon, I would recommend changing props to see what happens and it doesn't hurt to have a spare prop if you don't have one. There just may be a problem with the prop causing the erosion that severe. Talk to Eric @ OJ or Bill Weeks @ ACME for their recommendatios for your application.
I assume the '89 Barefoot 190 you have is the TriStar, with the 454C.I. and that situation may just be the nature of the beast as there are very few of those boats around! IMO
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Quote: 2RLAKE,
At some point in time people need to wake up, remove their cranial intrusion into their own rectal areas, and take responsibility for their own actions.





Last edited by TMCNo1; 06-30-2006 at 01:44 PM.
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