Crane, in "The Open Boat", conveys a deep sense of brotherhood between the men in the dinghy.
Given the scientific nature of Naturalistic writing, the men are left to fight against nature itself. Typically, Naturalists write from a perspective in which Nature will always come out on top. Free will fails to exist and characters tend to focus on how to better the circumstances around them.
Here, one could see that Nature has surrounded the men, their free will is gone, and that all they have to better their circumstances is brotherhood.The men know that regardless of the outcome, they are in this together. There is really nothing else to do but support each other.