The dispro ( a nickname for the disappearing propeller boat ) is a Canadian invention that went through a few incarnations between 1914 and 1958 . The boats were originally built in Port Carling Ontario , and after the insolvency of the Port Carling Operation the patent for the mechanism that allowed the propeller to be retracted into the hull in shallow water ( called the device ) was purchased by a company in Lindsay Ontario were these boats were manufactured for about ten years . After the insolvency of the Lindsay operation ( boat builders all seem to share this common trait --they all eventually go bankrupt ! ) The dispro patent was  aquired by Greavette boats in Gravenhurst . Over the years I have restored about fifteen of these boats from the Port Carling works and the Greavette works , but this was my first Lindsay boat . Of all the models , the " Sport special " was one of the most deluxe variations of The dispro .And by far one of the more challenging dispro restorations that I have tackled .