There are many versions of this song. I am posting the version recorded by Eilidh Mackenzie on "Eideadh na Sgeulachd – the raiment of the tale" simply because Ciarili had already typed it out on computer disc and I had only to add line breaks and diacritical marks. You will find most of these verses and a bit more at 'alltandubh'(click on the T for a list of songs beginning with that letter). The version there has different vocables, "àill i ó" & "hai ó" so perhaps it is sung to a different air; the site is Canadian based so it might present a version that is sung in Canada? This song has been collected in the the islands of the Uists and Skye and in northern counties of Ireland. I'm not sure where else it's been collected in Scotland. But although Eilidh Mackenzie and Christine Primrose, both of Lewis, have recorded it and Lewis men Domhnaill Ruadh, Iain Mac a' Ghobhain and Norman Malcolm MacDonald have made a film (A' Bhean Eudach) and a play (A' Bhean Iadach) based on the song and story; Christine Primrose told me that this is not a Lewis song and that she learned it out of a book.

The song is that of a drowning woman, in dialogue with the jealous woman who will not rescue her. A story is told about the song, and this story is much the same in Scotland and in Ireland. The woman who drowned was a married women with young children. The jealous woman (a' bhean eudach/iadach) was either a neighbour or a servant of the married woman. They were out on the strand at low tide gathering seaweed and shellfish. They sat down to rest and the jealous woman combed the other woman's hair. The married woman fell asleep, the jealous woman entangled her hair with the seaweed, and when the tide came, the married woman was trapped. She sang this song, and it is said that the jealous woman got away with her crime and took the other woman's place until one day the husband overheard her singing the drowned woman's song as a lullabye to the baby.
You can read a good rendition of the song – in Gaelic with full English translation - in Margaret Fay Shaw, "Songs of South Uist", which was reprinted in 1999. Shaw also includeds sheet music, lyrics and translation of the song.

I am interested in learning more about how the song has been associated with specific places where people say the event occurred. I have a photocpy of a manuscript which says "The people of South Uist say the scene of this is at Aird a' Mhachar, S. Uist while the people of mnorth say that the scene of the poem is at…" Alas, the second place name is completely illegible. (I don't know the author of the ms, but will ask the person who lent me the photocopy)
In an article in "An Gaidheal", March 1927, Alexander Nicolson says that the story is said to concern "Nighean Dhomhnuill Rhiabhaich" and that she drowned at Eilean [island] Tioram near Skye. There is skerry named "Sgeir Ni'n Dhomh'uill Rhiabhaich", and it is common to name these rocks after tragedies which occurred at them. "Caisteal [Castle] Thioram" is mentioned in a Uist version quoted in KC Craig, ed "Orain Luaidh Màiri Nighean Alasdair", Glasgow, 1949.

Titles of versions of this song include A' Bhean Eudach, A' Bhean Iadach, Bean Mhic a' Mhaoir, Bean Mhic a' tSaoir, Bean Ga Bàthadh, A' Bhean Ud(aí) Thall (there are also 2 other, different songs with that title). In versions called "Thig am Bàta", the song starts off with the boat coming to find the drowned woman; in other versions these verses are at the end of the song.

Recordings include (Scottish) Flora McNeill, Eilidh McKenzie, Christine Primrose (Irish) Pádraigín Ní Uallacháin, Altan, Neilí Ní Dhomhnaill, Jimmy Meehan

RTE (Radió Teilifis Éireann) cassette and book "Scéalamhráin" has both Irish and Scottish versions, including the one sung by Neilí Ní Dhomhnaill which was souped up by Altan.

Thig am bàta

Thig am bàta, hug-o
Moch a-maireach, hug-o
Bidh m'athair innte, hi ri o ro
'S mo thriùir bhràithrean, hug-o

'S mo chéile donn, hug-o
Air ràmh braghad, hug-o
'S gheibh iad mise, hi ri o ro
Air mo bhàthadh, hug-o

'S togaidh iad mi,…
Air na ràmhan,…
'S mo bhreacan donn, …
Snàmh na fairge,…

Cha b'e 'n t-acras
Chuir do'n tràigh mi
Ach miann an duilisg
'S miann nam bàirneach

' Fhir ud thall
Falbh na tràghad
Soraidh bhuam-sa
Gu mo mhathair

O mo mhallachd
Aig bean iadaich
Dh'fhàg i mise
'San sgeir-bhàite

Thig am bàta
Moch a-màireach
'S gheibh iad mise
Air mo bhàthadh

Translation
The boat will come
early tomorrow
My father will be on board
and my brothers three

and my brown-haired sweetheart
will be at the forward oar
and they will find me drowned
already drowned

and they will lift me
on the oars
with my brown plaid
swimming in the ocean

It was not hunger
that sent me to the shore
but a desire for dulse
and a desire for limpets

You, man over there
walking on the shore
say farewell for me
to my mother

O my curse
on the jealous woman
she left me
on a submerged reef

The boat will come tomorrow
early tomorrow
and they will find me
already drowned