I had a sailing test a few weeks ago and in it I was presented with the B flag and was asked what it means and what would be the applicable light at night.
I know the answer is "carrying dangerous substances and the light is an all-round red light" but I can't find where this is defined to make sure I'm not missing other rules not in COLREGs.
Are there any additional international rules for boating lights and signals apart from COLREGs?