Depending on the condition you may want to use the cleaner wax and polish approach.
Polishing pontoon railing. Find one you like such as Sharkhide or Bio-Kleen and use as directed. RETURN REFUND POLICY. As long as they are not ribbed wet sanding with fine sand paper works.
First wash the boat to remove any buildup of dirt grime mineral deposits or algae. Clean and polish the fence railing. This means that both the body of the pontoon and the tubes can be polished with the same materials.
Most available at auto zone advance auto sure auto geek carries it. Cleaningpolishing aluminum rub rails with a buffing kit. Use lower grit for bigger scratchs work up.
The quickest way I can think of is to start with a green substute sanding pad on the the ruff stuff to soften the edges and then switch to the red fine for the rest using soapy water and long strokes. Clean and wax steering console. Your rails will look like mirrors i promise.
Pick up only - no shipping. Our Pontoon Railing is 26 tall with the panel covering the bottom 18. Then hand buff with mothers.
Its time consuming but very very worth it. I tried the same buffing kit and it works but. Proper pontoon care always starts with washing and cleaning.