Analysis of Old Song Re-Sung

I saw three ships a-sailing,
A-sailing on the sea,
The first her masts were silver,
Her hull was ivory.
The snows came drifting softly,
And lined her white as wool;
Oh, Jesus, Son of Mary,
Thy Cradle beautiful!

I saw three ships a-sailing,
The next was red as blood,
Her decks shone like a ruby,
Encrimsoned all her wood.
Her main-mast stood up lonely,
A lonely Cross and stark.
Oh, Jesus, Son of Mary,
Bring all men to that ark!

I saw three ships a-sailing.
The third for cargo bore
The souls of men redeemed,
That shall be slaves no more.
The lost beloved faces,
I saw them glad and free.
Oh, Jesus, Son of Mary,
When wilt thou come for me?