Changing the colour to white is highly inadvisable. I suggest painting it as close as possible to the original colour. Otherwise, every scratch will shoe up blue.
I am very impressed with the durability of my awlgrip paint, and would never use anything else.
Touching up small scratches is easy.. I have a bottle of awlgrip touch up paint, and stratch repairs
are as easy as could be. I understand that larger repairs are hard to blend in.
I suspect that your hull is blue Awlgrip, not gelcoat
, in which case you do not polish it. That damages the finish. You could try Awlwash, followed by Awlcare.
On the other hand, if the hull really is blue gelcoat, it should be possible to sand down to non-oxidised gelcoat, and then polish.