I don't think that you could have or should have done more than you did. Most of the time - when bad things happen to people on boats, they survive. If something bad happened to those folks, and they lived - well they are probably not going to make the same set of mistakes again.
Some people can learn from others, and some people can only learn from themselves.
I agree with Cam , that if there were children involved, you would have had a moral responsibility to do more, but in the circumstances that you describe, you did the right thing.