electrolytic pitting

[belercous]

The most sacrificial material on my boat are the magnesium anodes. (I installed an extra one on the bracket for the depth finder) Zinc is a sacrificial anode in saltwater, but doesn't work good in fresh water. Freshwater anodes are magnesium, not zinc, despite people calling them that.

When I saw what the brazing rods were made of, I had the same reaction you did. I would like to have new logs (mine are pretty beat up from the places I've taken them), but they're certainly not cheap. Especially when considering the cost of shipping. If I were to get new logs, I'd want them to have a bit larger diameter as the aft end sits a bit low the way it is.

I should have the repairs completed by tomorrow evening, then I'll just need a couple more studs/washers/nuts so I can re-install the lower unit. I didn't mention it, but when I pulled the boat out of the water I found that the lower unit was only being held on by 2 studs. Which were also starting to loosen. Apparently, three of the studs vibrated completely free (well, the aft one was a bolt & I didn't know it should have been a stud, but it was flat-out gone). The lower unit was replaced with a new one (from an old [1980's] 3 years ago & apparently I didn't reseat the studs, allowing them to vibrate loose.

I have access to a reasonably priced older 175hp Merc engine when this one goes bad, but this one just keeps humming right along, always starting & running like a sewing machine. My transom is only rated for 150hp so I'd prolly need to beef it up for the extra 25 hp.

[FogHorn]

WORTHLESS this thread is..

[belercous]

I tried to post the pics, but it's fairly difficult to do on this forum.

[FogHorn]

Let’s see if this is easy or not:

[belercous]

I don't know why I couldn't get them to upload before. Since Dropbox started charging I used Google Photos.

Apparently I can't upload 8 pics. See next post for last 4.

These pics are, in order: 1., wire wheeled, pit Dremeled, 2., Same spot after brazing, 3., Same spot after grinding off excess, 4., same spot after touching up w/ more braze & grinding, 5., Rt aft outer log after wire wheel, 6., Lt outer log after wire wheel, 7., Lt frt log after wire wheel. 8., close up of generic pitting after wire wheel.

My camera was a 10 MP, set on the finest setting, yet I couldn't get the photos any sharper.

The weird thing was when I got to the center log, I was able to fill in 2 divots up high, but no other ones. I was running MAPP gas & it wouldn't get hot enough, even holding the torch on a spot for 5 minutes. I could touch a spot 3" away & it was fairly warm, but not hot. Certainly, this meant the log was filled with water, eh? Yeah, no. Tapping on it was not a dead or muffled sound. From an earlier run in with a hidden stump when I had the log repaired, I installed a drain plug to check to check for leaks & when I removed it the log was dry. Wtf?

I called the factory & was on the phone with them for a while. They found an employee who was there in 1994 when the boat was made & said they were making their pontoons back then & the AL used was 5052. That's a good grade of AL & it's alloyed with magnesium, which dissipates heat fairly quickly. But the center log was not made out of the same material as the other logs (it was a darker color & there weren't nearly as many pits on it). They had no clue as to what was going on. If I didn't know better, I'd have thought the metal was titanium. (I've ground titanium on a grinding wheel, throwing white sparks, then touched it a few seconds later & it was room temp. And titanium would be stupid expensive to make a pontoon out of.) I have no idea what the deal was with that log. Since none of the pits were all the way through & rainy weather was coming, I put the boat back in its slip.

I've got a boat mechanic that's gonna check my slip for stray current (I'm not certain on how to do that as I'm not a boat mechanic & this is the first boat I've worked on), but in the meantime I'm not leaving it plugged it to shore power.

I'm hoping that my fix will work as replacing the logs would be quite expensive & a real PIA.

[belercous]

[belercous]

I don't know if that even worked. Apparently I'm not smart enough to upload photos on this site.

[rickdb1]

https://www.pdbmagazine.com/pontoonf...sting-pictures

[belercous]

I'll try this again. This was my first divot repair. Since then I was able to fill most of the pits the first time & didn't need to go back over them.

Photo 1 shows a couple pits after the area was wire brushed & the pits were cleaned up with a Dremel
Photo 2 shows the pits after brazing & sanding
Photo 3 is after I went back over the pits, but before sanding
Photo 4 is the completed repair

I had a lot of these to do. I didn't braze over every pit (due to time constraints) but only the deep ones.

Photo 5 is the right aft log close up
Photo 6 is the left aft log
Photo 7 is the left front log

I also had to do the inside & underneath the logs as well.

[belercous]

Finally! I believe that I have successfully uploaded photos here.

While this brazing method isn't as strong as a weld, the material is harder than AL. It seems fit to be used for attaching/repairing a depth finder bracket.