Thanks ColC that is them.
I will look into the Abergwili baptism as I had not gone that far back, but a probable relative. These two generations are causing plenty of confusion.
Until writing my post, I had not considered them as father and son, but thinking of Welsh naming patterns he could be the first born male.
I have now found a baptism I would associate with Margaret Lewis:
Other Transcript Bethlehem Welsh Pwll-Trap Carmarthenshire
Birth: 08 May 1823 . Bapt: 18 May 1823
Anna Howell . Female
Father: Jonah Howell . Mother Margaret Powell
But; as they married in 1818, they could be living near Pwll-Trap before moving to Llansadurnen. It is the area where Jonah Howell Snr. was based. It would seem both families were using the Bethlehem Welsh chapel in Pwll-Trap.
The two marriages I have. The second was found on FreeReg as it was not on Family Search:
Marriage: 10 Jan 1818 . St Sadwrn Parish Register Llansadwrnen
Jonah Howell . Bachelor . Eglwys Cymmin . Margaret Powell . Spinster
Marriage: Joha Howell . Margaret Lewis
15 Mar 1821 . Laugharne, Carmarthenshire . Page 37
Affiliate Publication Number 189
This marriage seems to be second time around for him, but no further information has been transcribed.
I have found several of their children in Bethlehem Welsh Pwll-Trap.
There is this marriage:
Marriage: St Canna Parish Register Llangan Pembrokeshire
12 Jul 1806 . Jonah Howell . Anna John . Spinster
I am finding possible births, but the father’s name is only recorded as Howell with no mother named.
LLANGAN, a parish in the district of Narberth and counties of Pembroke and Carmarthen; on the river Taff and 2 miles WNW of Whitland rail station.
http://www.visionofbritain.org.uk/place/6371Somewhere I have a record, but cannot locate it at present, that he was born in Henllan Amgoed, so the same area.
I am looking into the sailor link. It looks like the boat was handed down the generations. Jonah Jnr was a labourer and then became a sailor. My great-grandfather Thomas Williams was a labourer who later became a mariner. It looks like they become sailor/mariner when the previous generation has died. Could this be the same boat?