Deck overhang - Sponsons (Sponsing)

[Les Jones]

I am researching a new project of the Holyhead Royal Mail Packet "Escape", built in 1824, later renamed "Dotterel" when taken over by the Admiralty in 1837. It seems that the deck overhangs the hull by roughly half the width of the paddleboxes. This is termed as "sponsons" or "sponsing". Certain drawings show the support of the outer edge of the deck by a brace or bracket. Some show that these brackets are also planked over to form part of the hull shape. Does anyone know if this is correct and was it common practice in the first half of the 19th century?

While I'm about it does anybody know where I can get a general arrangement drawing of a Boulton and Watt side lever engine? I have details of installation and even detail drawings of components but nothing to show the whole thing.