I’d never heard this term before, but Nicholson puts it in quotes, suggesting it is some kind of workman’s slang, or at least an uncommon term. In describing cloth case binding, and how to use a plough, he writes. “If the volumes are small, a number may be cut at the same time. This mode of cutting is called ‘steamboating'”. This was originally written in 1856. Perhaps it is emblematic of the 19th century preoccupation with steam power in general, and how a machine can influence even the terminology of hand work.
A 19th century bookbinder ploughing a book. Original size roughly 1 x 1 inch, which may account for some of the missing lines on the press and the tub. Even in this small illustration, the downward pressure of the binder is evident, which is necessary to achieve a straight cut. Also, his left foot appears to be slightly raised, also implying heavy pressure on the plough, and a speedy rocking motion with the body. Illustration from: Nicholson, James B. A Manual of the Art of Bookbinding: Containing full Instructions in the Different Branches of Forwarding, Gilding, and Finishing. Also, The Art of Marbling Book-Edges and Paper. The Whole Designed for the Practical Workman, the Amateur, and the Book-Collector. Philadelphia: Henry Carey Baird, 1874.