The rubrail seems firmly attached, at least I grabbed it and tried to pull on it. That was when I was taking the first picture in this thread, while standing on the outside.
It looks like they tapped holes to screw the screws into. Only for some reason, they tapped every hole all the way through.
Fun fact #2484: In my avatar, that's DavidPM at the helm of my boat.
Bland, non-political statement goes here.