Notes

the opening couplets of the first two stanzas establish a happy mood, which set side by side with the shortened succeeding lines, brings out the disappointment experienced by the poet over the captain's death. Note the progression, Stanza 1 begins with two happy couplets; Stanza 2 begins with two celebrating couplets, but something isn't quite right which is shown by the off rhyme of "bells" and "trills." Stanza 3 re-establishes the rhyming couplet pattern, but the message is as clear as the rhyme is, the captain is dead.
There is no fixed meter, there is however, a pattern of four long lines followed by four short lines in each stanza. The shortened lines emphasize the personal grief experienced by the poet against the backdrop of a broader victory. The poem's rhythm is created by the varying line lengths. The captain is Abraham Lincoln. The fearful trip is the Civil War. The ship is the United States. The prize is the preservation of the union. The repetition of "heart" in line 5 emphasizes the poet's grief at the death of his captain. "Fallen cold and dead" is repeated at the end of each stanza to emphasize the poet's deep loss.