After reading many posts on here, I have not been able to find an answer to my question. I recently built a jackplate in my garage for my 24' pontoon. I mounted a 70hp Johnson long shaft on my boat. The transom had been modified in the past (before I owned it) for a short shaft engine, so this engine had to be raised. I made it using 1/2" thick 6061 T6 aluminum angle and 1/2" SS bolts. Everything mounted up and it looks good. There is no play in the engine. I took it out Saturday for its first trip to try it out, and it worked flawlessly. Today, however, I noticed what looked like oxydation on the aluminum. Is this normal? Or have I done something wrong?
