Hi Diane
The information came from the Merchant Seaman's Benefit Society records which are lodged at the Societe Jersiaise Library. The 20 (approx) volumes details the amount paid by each seaman who sailed on a Jersey registered boat. You can cross reference the seaman's payments to which boat he sailed on.
Someone has gone through the records and extracted all seaman marked as "dead" and produced a typewritten list. On occasions they have crossed referenced the list to the Jersey Chronique newspaper for more details.
This is where I found the death of Charles Harvey. I have not looked in any of the microfilms of newspapers as I cannot read French and there are no other records available on-line.
I am told by the Archivist that it is possible to get further details but these would be at the National Archive where again nothing is on-line. Have a look at
http://www.catalogue.nationalarchives.gov.uk/researchguidesindex.asp in particular the records under Merchant Seamen and Birth, Marriages at Deaths at Sea.
Stewart