Ah, found this on an old thread. Doesn't sound quite the same as Johnson Girls, anyone got different/additional verses?
LYRICS:

Six o'clock I hear 'em say
Chorus: Sun down, sun down below
Six o'clock I hear 'em say
Chorus: Sun down, sun down below

Aye-a-a-a-a
Aye-a-a-a-a

The day's been hot, you all do say
Time to quit and go away

Aye-a-a-a-a
Aye-a-a-a-a

Sun is down an' I must go
Sun is down in the hole below

Aye-a-a-a-a
Aye-a-a-a-a

I hear my captain say
Sun is down and I must go

Aye-a-a-a-a
Aye-a-a-a-a

Pack our duds and dinna' pail
Come back sure befo' you sail

Aye-a-a-a-a
Aye-a-a-a-a

(as posted by Radriano)