I first heard this at a London Shanty Collective zoom session (January, 2021 - I'll track down who sang the song and add it to this thread). The only recording I could find was by Gordon Bok. Sail, O Believer is one of the songs in the book "Slave Songs of the United States, 1867": Sail, O Believer is shown to come from the Port Royal Islands, C.P.W. It's a rowing shanty: "Among the most common rowing tunes were Nos. 5, 14, 17, 27, 28, 29, 30, 31, 32, 33, 36, 46. "As I have written these tunes," says Mr. Ware, "two measures are to be sung to each stroke, the first measure being accented by the beginning of the stroke, the second by the rattle of the oars in the row-locks. On the passenger boat at the [Beaufort] ferry, they rowed from sixteen to thirty strokes a minute; twenty-four was the average."

SAIL, O BELIEVER

Grand chorus:
Sail, o believer sai
Sail over yonder
Sail, o my brother sail
Sail over yonder

Verse 1:
Solo: Oh, brother, bear a hand
Ch:   Sail over yonder
Solo: Come, my brother, bear a hand
Ch:   Sail over yonder

Verse 2:
Come, view the promised land
Sail over yonder
Come, view the promised land
Sail over yonder

Verse 3:
Oh, Mary, Mary weep
Sail over yonder
Bow low, Martha
Sail over yonder

Verse 4:
Oh, my Lord's coming now
Sail over yonder
And my Lord locks the door
Sail over yonder

Verse 5:
Now my Lord's locked the door
Sail over yonder
Carries the keys away
Sail over yonder