Hi Jake:
Yes, it is quite true. The stern-attached OB brackets used on MOST boats are made from aluminum, so they need to be painted using an anti-fouling paint or paint system that is compatible with aluminum. Galvanic corrosion caused by the reactions of dissimilar metals in a saltwater environment looks like this, from my actual boat (
before I corrected the situation caused by the former owner).
There is another good picture of this occurring
in this post here at the bottom of page 1.
Painting:
There are 2 ways to do this.
Method (1) uses an aluminum-compatible paint like Tri-Lux 33, following the mfgr's instructions to the letter. Tyically $40/pint and $60/quart.
Method (2) can also be used and is best IMHO if you are also going to paint your SS trim tabs, as you then don't need to buy special paint just for the aluminum. If just doing the OB bracket, I'd use #1.
Done properly, Method 2 isn't a cheap process (~ $80 for 2 quarts, 1 each, less bottom paint) as it is a 3-part process. The 1st part etches the material, then you put on a tie-coat primer (rubber-based), and then top off with your anti-fouling paint of choice. Pettit's metal prep system is reputed to be the best and I'd say if my results are indicative - it seems to be!
Bonus! Since the rubber-based primer insulates the aluminum from any cuprois oxide used in the anti-fouling paint,
now you CAN use your existing bottom paint on the bracket!
Etch:______________________________________Tie Coat:
-
FWIW I had poor results :shock: with that expen$ive Primacon anti-F crap spray-paint stuff, but my attempt was on SS.
Removal:
I'd use a stripper and sand aggressively and possible a wire-wheel to remove the old copper-based paint. I will say I didn't remove 100% of it andI have had zero issues since using the Pettit 3-step process.
Here is a post with photos showing the 3-steps in acrton on SS Bennett trim tabs,
click here.
Hope this helps you

!