Weeping Rust on Rudder

[guidothesquid]

After reading the amusing thread about the Rusty Trim Tabs Tabs, viewtopic.php?f=2&t=8818 it reminded me of an issue that Double J diving finds on Tug Toy when they dive and change the zincs. There's weeping rust on the rudder, and after they clean it up there's visual signs of corrosion. Now, I thought this wasn't supposed to happen, with the metal types and the zincs and proper maintenance and all, but I'm missing something.

Here's a few pictures from the dive last February:
gallery2.php?g2_itemId=48061
gallery2.php?g2_itemId=48063
gallery2.php?g2_itemId=48059

Any thoughts?

 

[baz]

First off.... I don't have any explanation for this at all. It looks so very weird and marshmallow-like in appearance. Weeping is a good 'descriptor' for this rusting issue.

It would be of interest to know if others with the R-25SC (same model year as well) see a similar affect.

Have you discussed this with Kenny/Andrew for their inputs as to what's going on.

I also use the services of Double J Diving and they provide excellent work and I really enjoy the underwater photos they supply me with. They started doing this (capturing photos) maybe 4 years ago at no additional charge.

Also, as Double J Diving performs zinc/anode replacements on many boats can they say whether they've seen this issue on other boats, other Ranger Tug R-25s.

Double J Diving performed my R-25 (Classic) under water zinc/anode maintenance at the Port of Edmonds (kept at same dock as what you're in today) and never ever showed me similar photos of the rudder assembly rusting issue you have on your R-25SC.... and I'm sure they would have alerted me to it had they come across it.

Very odd.

 

[Brian B]

I have a 2010 25SC and never had an issue as you describe in the photo's. I paint all the underwater metal with Petit Zinc Paint # 1792. I will get some slime after 6 months but that's all. Could it be the microbes that live in the water where you dock the boat, electrolysis etc.. Is the rudder post properly bonded to the boats system?

 

[tlkenyon]

The rudder is not steel or iron and therefore cannot rust. Not sure what that stuff is, but it cannot be rust.

TK

 

[knotflying]

The rudder is 70% Manganese Bronze that is cast around a stainless steel shaft. Something interesting is going on here. I use cold galvanized paint on all my running gear and have no issues. You may want to contact Marine Hardware http://www.marinehardware.com/ and ask them their opinion. They are the suppliers of the hardware.