The gel coat on your front cap is relatively thick compared to the sidewalls. I would try first wiping the blue area with acetone to see if any color comes off on a white rag. If solvent does not remove it I would try a 1000 grit sand paper and then use a polishing compound with an electric buffer. Just be careful not to apply too much pressure and burn through to the fabric with the buffer. I just got through doing this to remove stains in the gel coat of a FG boat hull and the 1000 grit paper worked good. The paper and polishing compound can be bought at HF, you can also buy it at a Marine store for twice the cost.