As gp said, you could tell people exactly where you are, but it takes a long tome for anyone to be able to reach those coordinates by ship. If your power source

As gp said, you could tell people exactly where you are, but it takes a long tome for anyone to be able to reach those coordinates by ship. If your power source dies and you drift in the interim, now it takes many ships and a coordinated effort hopefully involving aircraft for a chance that you’ll be found. The ocean is a very large place and a ship doesn’t exactly leave tracks.