What does Roguish Eye refer to in Rain Rain The Wind Doth Blow?

The song is actually a riddle. Merrain Richardson (not sure of the spelling)is the name of a ship caught in a storm. A "roguish eye" is a lighthouse. Some versions of this folksong refer to is as a "rolling eye". Each verse of the song is a little bit of folk history about this ship. Each verse is a riddle. "Rain, rain the wind does blow. Stars are shining to and fro. Merrain Richardson said she'll die, if she don't find the fellow with the rolling eye."

"...She is handsome she is pretty, she is a girl from the Halifax City. She has lovers one-two-three. Please tell us who they be..."