RootsChat.Com

Sorry to hear about the tragic circumstances of this young man.
Have you tried getting a copy of his death certificate?  The Genealogist has an excellent Overseas BMD section, which lists the details in the same way as the General Record Office (GRO) Index.  His death certificate would show details of his occupation which may well give the name of his ship, from which you could find the shipping line.  If you have the name of his ship, it may give more details about him in the ship's log.
I have been able to obtain copies of merchant navy records of various family members - seaman's pockets - which listed the ships they served on and the dates, available from the National Archives (at a cost of course!).  You will need his full name and date and place of birth, so you may need to get a copy of his birth certificate first, to make sure you have the correct person. 
Apologies if you have already tried this and I am teaching my granny to suck egs.  Good luck.

James MCNEA, Architect (b. 1815)
Info that may help in search of forbears of James McNea.
You'll have to delete 'Grand', also exchange  'brothers' and 'sisters' for aunts and uncles!

The 1902 medical history of his son, Walter H McNEA (1861-1902), gave the following information:
Family History section:
Paternal Grandfather: died age 30 years, cause of death - fever
Paternal Grandmother: died age 90 years, cause of death - old age
Paternal Uncles: died - one aged 70 years, one aged 72 years
Paternal Aunt:  died age 70 years

As promised, here are details of James MCNEA and his wife Margaret HUNTER.  I had hoped to do a copy of a file I have but have been forced to re-type the main details, which exclude specific sources but you can find them from the website info I have given you. 
Anything which I haven't made clear, please contact me.


James MCNEA and Margaret HUNTER

Margaret HUNTER
Birth: 1819? Ireland (source 1845 marriage – ‘age 26’, death certificate ‘age 64’ b.1828)
Father: James HUNTER (see note below)
Death:  17 Nov 1892, Bootle, Lancashire (source Death Certificate)
Marriage: 10 Jun 1845, St Annes, Belfast to James MCNEA, Architect (Ulster Historical Foundation (UHF)
Children:
Mary Ann MCNEA (1850-1925)
Elizabeth Grace MCNEA (1850- 29 Aug 1926 Lancs)
Margaret MCNEA (*24 Nov 1850 – still alive 1911 Ireland census)
James Alexander McNEA (*29 May 1853 – ? received WW1 Merchant Seaman’s Medal)
Harriet Jane “Hattie” MCNEA (*26 Aug 1857 – 24 Aug 1935, Southport, Lancs)
William Gibson MCNEA (1858 –
Walter Hunter MCNEA ( *13 Dec 1861 – 15 Dec 1902, Winwick, Lancs)
Clara Maude Maud MCNEA (*17 Feb 1865 – 24 Nov 1944 Southport, Lancs)

Notes:
Marriage details:Margaret HUNTER’s father is shown as  James HUNTER, occupation Clerk to the Manor Court.  Witnesses at her wedding were Thomas HUNTER and William HUNTER – were they her brothers/uncles?   An 1843 List of Petty Sessions for County Down shows  place where held: Hillsborough, Clerk : J & JW Hunter

20 Sept 1875 St James Church of Ireland, Shankhill, Belfast - Margaret MCNEA (b1850) married William NASH (1821- 28 Nov 1929, Great Crosby, nr Liverpool, Lancs)  (source Marriage/Death Cert).  The 1901, 1911 Ireland Census shows they did not have children. 
13 May 1894 St Mary’s Kirkdale, Walton on the Hill, Liverpool – Walter H MCNEA married Mary Robina ROUTLEDGE.  They had a son, Walter Hunter MCNEA b 1895 Liverpool. (source Marriage, Death Certs, UHF report)
Mary Ann MCNEA – WH Mcnea’s 1902 medical records showed Mrs Fryd had 9 children.  Thinking that sadly one had died, I checked the freebmd website and found that Alexander and Herbert were one and the same person. 
Elizabeth Grace MCNEA – her death certificate describes her as ‘spinster daughter of James McNea, an architect’.
The sources for the *births in Belfast are from the baptism parish registers of Shankhill Parish Belfast, St Annes Church of Ireland 1824-66 (UHF report).  The details of deaths are from the death certificates I obtained.  As far as I can see, only Mary and Walter had children.  Hattie and Grace and Clara Maud all have ‘daughter of James McNea Architect’ on their death certificates.  Walter has ‘Father -  James McNea Architect’ on the marriage certificate, so I know I have got the right family and not cousins.
William Gibson MCNEA – he is named on the 1902 medical file of WH McNEA (b.1861) as one of his siblings.  Mary Anne MCNEA is shown as Mrs Mary Fryd on the same document.

James MCNEA
Birth:.1815 – age 30 years at time of marriage to Margaret HUNTER in 1845
Father: James MCNEA, Farmer (according to James McNEA’s  marriage certificate)
Marriage & Children: see details for Margaret HUNTER
Occupation: Architect: see also website of Irish Architects, Irish Architectural Archive for descriptions of building he undertook. 
Further info on addresses in Belfast, business and residential on lennonwylie website (ctrl F search McNea)
First appears in England Lancashire Census in 1891 as do the spinster daughters.
Death: 5 Jan 1896, Crosby, Lancs.  Buried in Anfield Cemetery, Liverpool.  Family members also in same plot include Margaret (wife) and daughters Eliz. Hatti and Maud.  Also Henry Nash and Margaret Nash, although the description on the death certificate I have for Margaret Nash shows her more likely to be Henry’s sister than his wife Margaret (nee McNea).

Sorry if it is all scrunched up, wasn't when I typed it!
Rgards Sue

Mrs Mary FRYD appears as a sister to my great grandfather Walter Hunter MCNEA (b1861).  Her name appears in the Brothers and Sisters section of the 'Family History' on a 1902 medical file for him.  I thought I had the details of all his brothers and sisters from a parish register research done over 20 years ago.  But this medical document also shows a further brother - William Gibson MCNEA to add to the list.  I had a quick look on the Irish History Foundation website and a Mary Ann McNEA married in 1869 and her father's name is James McNea.  But to be absolutely certain you need to get hold of a copy of her marriage certificate.  My Great Great Grandfather was James MCNEA, an Architect  and his wife was Margaret Hunter.  Once you have a copy of the certificate, let me know and I will send you a list of the other brothers and sisters.
As an aside, when researching MCNEAs in the London Gazette, I came across Emil McNea Fryd - if you haven't seen this already, just google London Gazette and do a search.
I have only just registered on this site in order to answer your query so not sure about the etiquette etc about further info.  I see Otto has posted, if he reads this I hope he will let me know.