This is a brilliant response. Many thanks to all.
Susan Jackman died in January 1918 and was buried at St Mary's with her first husband Samuel Crocker who drowned in the storm of 1866.
An extensive report of the wreck of the steamship Excelsior here:
http://www.plimsoll.org/resources/SCCLibraries/WreckReports/14950.aspThe Excelsior that collided with the French vessel was owned by the port of Cardiff so if this is the correct Excelsior, the steam ship carried a crew of 20 and it is possible that Wm H Jackman may have joined the ship on a voyage after the enquiry, but he was really a fisherman so is it surprising to find he had become crew on a steam ship? There was a Brixham cutter "Excelsior" BM54 launched in 1888, so that shouldn't be it. (Also "Excelsior" BM89 which was launched 1910.)
Re parents: there is a William Henry Jackman listed in Brixham who was with Ag Labs, but I think the Bap: 14 April 1839 with Henry (fisherman) and Katherine is far more likely. Also, tenuously, one of his and Susan's daughters was given a 2nd name Louisa.
First marriage - I have given this June 1/4 Newton Abbot ref some thought, although I can't find a suitable death for Jane, (or Elizabeth as offered by familysearch) there is a death registered for a 23 year old Sarah Jackman reg at Sculcoates in Dec 1/4 1867,
and the Brixham fishing fraternity often pop up in the Hull area so that would be quite possible.
Many thanks everyone, I think you have made progress.