Chords that have an equal length are called congruent chords. An interesting property of such chords is that regardless of their position in the circle, they are all an equal distance from the circle's center. The distance is defined as the length of a perpendicular line from a point to a line.
personification to give the foam a human quality metaphor to compare the boat to the sea a change in the rhyme scheme alliteration to add a musical quality to the poem.