Can you please paraphrase this sentence?"Some men die at ebb tide; some at low water; some at the full of the flood; and I feel now like a billow that's all one crested comb..."
The rest of the quote continues, "I am old--shake hands with me." The previous points in the conversation are leading to death. The old man is telling Starbuck that he does not know where or when the hour of death will come, but he knows that since he is old, that the hour must be close at hand. I believe the definition of comb used in this quote would be that of a wave- (A comb is sometimes used to describe certain types of waves). So when he says that some men die at every station (Ebb tide, low water), he feels that he is at and has been at every station and that death is at hand.