I'm not sure how to classify the Zorb. Does it count as a watercraft/vessel?
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This odd vessel is a lighter built by Samuel Pine in 1882 at Long Island for Senor Diaz to serve in the lighterage service in Cuba. What made it unusual was that it was propelled by two screw type propellers mounted athwartship, an idea pioneered by a man named Mr. Root (the book on steamships does not mention his first name). He had proposed the idea to the American Society of Engineers after running model tests in 1873. Root's theory was that a side mounted screw acting as a paddle wheel would be more efficient than conventional screws, not necessarily faster, but less fuel consuming.
I originally posted this in Merchant Ships but decided to move it here as this thread was more appropriate.