I don't much about rules, but I think the starboard boat does not have any obligation to hail you. It's your obligation to watch where you are going when you are on port.

I learned that one time when I was racing in a major Sunfish regatta and we were on chartered boats that had no windows in their sails. I was warned by some of the other sailors -- and found it to be true -- that the starboard boats were not going to hail you in a port-starboard confrontation. The onus, I believe, is on the port boat to be aware of starboard boats and to stay clear of them. In the case of the Sunfish, this required a lot of athletic flexibility to be able to keep bending down far enough to see under the windowless sail.

If somebody knows otherwise, please chime in.

P.S. Obviously, the starboard boat also has an obligation to avoid collision -- I was just talking about the obligation to hail.