I wrote here about Watson’s Double Canal Boat, saying inter alia that, in 1839, William Watson, manager of the inland department of the City of Dublin Steam Packet Company, patented:
an improvement in the construction of ships, and which improvement is also applicable to all kinds of sea-going vessels; and also certain improvements in the construction of boats and other vessels intended to be used on canals and inland navigations. 
I quoted the Mechanics’ Magazine of December 1839, which said that:
Three canal barges have already been built upon Mr Watson’s plan of construction, of 60 tons burthen each, and with eminent success.
I said that the size suggested that these canal barges were for the CoDSPCo’s Irish inland operations, but that I had no information about where they were built. I have now found information about one builder.
On Thursday, the 22nd instant, a fine new trade boat, built with iron ribs, according to the patent of William Watson, Esq., and belonging to the City of Dublin Steam company, also a new smack, 50 tons measurement, were launched from the Brunswick dock-yard, Ringsend Docks.
I would be grateful for more information.
 “List of patents granted for Scotland from 18th March to 18th June 1839” in The Edinburgh New Philosophical Journal , exhibiting a view of the progressive discoveries and improvements in the sciences and the arts Vol XXVII No LIII — July 1839; “List of English patents granted between the 25th of May and the 25th of June, 1839” in The Mechanics’ Magazine No 829, Saturday, June 29, 1839
 The Mechanics’ Magazine Vol XXXII No 855 28 December 1839
 The Freeman’s Journal Saturday 24 July 1841. An almost identical note appeared in the Dublin Evening Mail of Monday 26 July 1841.