Took a walk down to St Katharine's Dock near to Tower Bridge during lunch. I was struggling to come up with an image today beginning with 'K' and thought St Katharine's would do...(I was holding 'keys' back in reserve).
Decided to use thesaurus just to see if barge/boat had an alternative and hey presto.... ketch... Must admit to having never heard of the word... But hey, I am a product of a Thatcherite education...!!!!
Blue skies and a bit warm in London today... hurray!!!
Andy...for what it's worth, a ketch is a two-masted sailboat, with the forward mast larger than the aft mast. And as far as I know, those are really ketches in your picture.