I guess the reason these areas rust is because there is a gap at the top that lets condensation run down into there.
I asked the question as when I laid out the patch and put a strait edge on it top to bottom, I was surprised the angle of the bottom was so far off.
Some of the rust was back past the lip where the bend is, thus the messy weld. This will need some further fill welding.
It does look much more wavy in the photo than it really is.I'll probably have to use some epoxy filler to finish it off nice.
These windows were put in with a butyl strip originally. These may still be available, but I'm going to use a Sika polyurethane to get the height right as well as for safety.
You're right about the improvement in materials there!
Anyway, thanks for the help, It's really appreciated
Here's another shot that looks "less" wavy Ha ha
