The standard rust streak cleaner in America seems to be a dilute phosphoric acid solution sold as OSPHO. I used it all of the time when I owned a steel
boat, and it worked real well. With your dark blue hull
you might want to try it in an out of the way spot to see if it dulls the paint. I assume you are in Aus. and paint stores would have a similar product. I also used OSPHO on my fiberglass
boats to clean up rust weeps from so called stainless steel
. Give it a try. It beats buffing. _____Grant.