MGY--To answer your question about drifting. It would be possible that the lifeboats were moving around pending on if they were moving or not. The Labrador current was moving both the Californian and the Titanic. So I do believe the boats could have drifted from the sinking position. When the Carpathia arrived and spotted the lifeboats, many of course took a bit to row up to her. I believe the last rescue was at 8:30am. They began taking passengers on at 6:10am.

I doubt that the Californian was more than 12-15 miles away based on you wouldn't be able to see the Titanic based on the curvature of the Earth. The Californian had a very powerful Morse lamp that could be seen from 10 miles away as Lord stated. That could explain why both were signaling like crazy and getting no responses. If you check that link I posted above, it will give you a good idea on plotting where the ships were. The man who constructs the website went to Harvard I believe. He's very knowledgeable on the issue of the Titanic and the Californian. Enjoy.