Hello Bumblebee,
Seaweed's information suggests to me that Mary Vernon was a wealthy society woman and SOLANGE was a personal pleasure craft.
Something that I have learned in research is to never be afraid to detour sideways in the hopes of moving forward. A quick Google turns up nothing about "Vernon +Pembroke Works", but a quick skim of British Newspaper Archive for "SOLANGE +Vernon" does turn up this:
Hampshire Telegraph
FALL FROM A YACHT
... Easter Monday brought tragedy to Mr. and Mrs. U. S. Vernon, one of their three little children being drowned in the Chichester Canal by falling in, some way unknown, from the deck of their motor yacht Solange, which is moored in the lower lock. Birdham. The ...
Published: Friday 21 April 1933
Newspaper: Hampshire Telegraph
County: Hampshire, England
Type: Article | Words: 195 | Page: 11 | Tags: none
I don't have a sub to either BNA or FindMyPast (which includes BNA) so can't read the actual article but there may be leads there - an inquest perhaps? names of crew members who dove in to try to rescue the child? the father's occupation? Learning more about the Vernons and their travels may also tell you more about your grandfather's experiences.
And ... if they were society people, you may turn up a photo of SOLANGE. One possible source that comes to mind is The Illustrated London News archive.
Cheers,
Westoe
EDIT:
You wrote in post #1 of this thread: "Solange was also destroyed before the war."
That may not be so. Here's another snippett from BNA using search parameter "motor yacht SOLANGE":
... Weather Drove Them In Bad weather last week-end sent two vessels into Harbour for shelter. One of them, the motor yacht Solange (19 tons), owned by Mr. H. F. Owen, of Shoreham, was assisted to a point near Ramsgate by Deal boatmen after she had been seen ...
Published: Friday 19 December 1947
Newspaper: Thanet Advertiser
County: Kent, England
Type: Article | Words: 133 | Page: 4 | Tags: none