Hi there
According to the book 'Guinness Book of Motorboating - facts and feats'
'The first boat to be powered by the internal combustion of a mixture of air and petrol inside the cylinder was built by the French inventor, Jean Joseph Etienne Lenoir (1822-1900) for M. Dalloz who was the Manager of Le Monde Illustre' newspaper in 1865. The 40-footer (12m) boat was equipped with a 6hp Lenoir engine, and despite its low speed and high petrolem consumption Dalloz used it on the Seine for two years to commute from Paris to Charenton.
In 1880 the American inventor, Brayton is reported to have installed his version of the internal combustion engine in a boat.'
food for thought though......
'Electric propulsion in boats has been around since approx the 1840s' - I wonder if there could be an electric motor in your boat? In 1891 there was an electric launch built for the Royal Navy and she was called Electric, built by Messrs Woodhouse and Rawson of Kew for harbour use.
food for thought eh....
aye
john