Stainless Prop Film

[JimS123]

I really don't like People learning about the Shocking Truth of Electricity, anywhere near Water. I know that any Power to a Dock would have to be on an Isolation Circuit, and should be safe, but there shouldn't be any Stray Currents. I suspect the Marina cut some Corners somewhere and the Wiring isn't to Code

Could be.

I my case I was in a marina with floating docks. So, it was still usable. However, the river had flooded and the "Dock House", which was on land, was flooded as well. I assume that some of the electricals were under water.

Our normal waterfront motel room was also half flooded, so we had to stay in a cottage up the hill. Odd vacation to say the least.

 

[Chris1956]

That is not galvanic corrosion. I ran a SS prop in salt water, and used to get a bit of classic galvanic corrosion where the blades met the hub. I had zinc anodes and an impressed current (MerCathode) system on the boat. It protected the outdrive just fine.

However, you might see if it is recommended by the prop OEM that a continuity washer should be under the prop nut, to ground the prop to the propshaft, however, that will not fix your discoloration issue, IMO. You might invest in some jeweler's rouge and a buffing wheel to make restoring the shine easy. Clean it up and put some wax on it to keep it shiny longer.


You mention that a ground strap fell off, and you neglected to reattach it. since you have a fiberglass hull, the engine is grounded via the ground cable on the battery. No additional strap is necessary for the engine to be grounded properly.

Ground straps should be on metal thru-hull fittings, metal fuel tanks and like items.

 

[racerone]

Doubt that is corrosion.----Some minerals " plate out " on metal submerged in lake / river water.-----Scrape it off / wash it off and buff.

 

[csukraw]

I posted about this a month ago or so but have a new scenario/developments. I took my boat out to Havasu last weekend for 3 days. Stainless Power Tech prop looked like the first pic before I left. I had just polished and waxed it. After taking it out it looked like the video and I was able to scratch off the coating. I’ve been out to Havasu many times with my boat and have never had this happen before. Photos of my anodes as well, they seem ok but I will be replacing with magnesium. Any ideas?

 

[csukraw]

Similar situation a month ago after going to Mohave for a few days. Although that time the coating didn’t come off as easily and I had to scrub it off with CLR.

 

[jimmbo]

Have you made any Changes to the Boat's Electrical System, added any new Accessories, repaired/replaced old ones?

 

[csukraw]

Earlier this year yea. New stereo system and bilge pump. But I had a few trips after those that didn’t affect the prop. Then two in a row that did.

Have you made any Changes to the Boat's Electrical System, added any new Accessories, repaired/replaced old ones?

 

[jimmbo]

Is the Gimbal Housing/Outdrive housing Grounded?

 

[csukraw]

Is the Gimbal Housing/Outdrive housing Grounded?

I don’t know. But haven’t touched anything like that since before it started happening.

 

[Scott06]

UPDATE: A little scrubbing with CLR and it came back. Not sure what the issue was exactly but it’s looking like it did before now.

I get the same thing on my merc props in fresh water as well. CLR or dollar store toilet bowl cleaner seems to work

 

[dingbat]

Here is a test for you......
Remove the positive battery cable from the battery. Test for continuity between the positive battery cable and the prop.
Should be an open circuit.

Next, test for continuity between the prop and the negative battery terminal.

Once confirmed, switch your meter over to "Ohms" and check the resistance
between the prop and the negative battery post. Ideally, should be less than 1.0 ohm