Personification : Whitman has used personification to give human qualities to lifeless objects. The speaker struggles with balancing his personal feelings of loss with the celebratory mood resulting from the successful voyage.
Imagery : Imagery appeals to the five senses of the readers. The keel has been thrown in to steady the moving ship.
This particular poem explores a variation on that theme: the self vs. The sailor reminisces about the trip to be extremely arduous yet they crossed the line with a trade-off.
The poem is an extended metaphor: 1 Lincoln is the captain who has "fallen cold and dead," having been assassinated shortly after the Civil War had ended; 2 the "fearful trip" is the Civil War; 3 "the prize we sought" is the preservation of the Union, something which both Whitman and Lincoln felt was the supreme reason for fighting the war; 4 "the ship" is the United States.
The speaker, torn between relief and despair, captures America's confusion at the end of the Civil War.