Securing Grab bar

I have a grab bar already installed but was wondering how I could reinforce it so it doesn't give when holding on. Heres my dillema: One side is mounted with angle aluminum to the rub rail/ on top of, with what looks like self tapping screws that do not go all the way thru the rail. The left side is mounted to the center/ backside of the center box with thru bolts and an aluminum backplate inside of box. I was wondering if just simply drilling out thru the rail and using thru bolts to secure the one side would help or should I start by reinforcing the inside of the center box to distribute the load more accordingly. Im just afraid I might need to use the grab rail one day and do not want to be in the water with it still in my hand.. Im going to post pics this afternoon to help clarify my explaination. I now its a little much to understand without pics. Thx