The Disappearing Propeller Boat

On August 8, 2015, during the centennial celebration of the Dispro Owners Association, a provincial plaque commemorating The Disappearing Propeller Boat was unveiled by the Ontario Heritage Trust and the Dispro Owners Association at the James Bartleman Island Park in Port Carling.

The bilingual provincial plaque reads as follows:


    Popularly known as the Dispro, or Dippy, this small boat was first built on this site in 1916 by the Disappearing Propeller Boat Company Limited. Also manufactured elsewhere in Ontario and briefly in the United States, more than 3,000 were built and sold around the world when production ceased in 1956. Boat builder W.J. Johnston Jr. and machinist Edwin Rogers invented a device that allowed the propeller and shaft to be retracted manually or automatically into a protective housing while the engine was still running. This patented design offered protection from rocks just below the surface in lakes of the Canadian Shield. Built in several models ranging from 16 feet to 19 feet (4.9 metres to 5.8 metres), the boats were constructed of overlapping cypress planks fastened to steam-bent oak ribs. Most were powered by single cylinder, 3-horsepower engines. Simple, versatile and durable, these boats were a common sight on Muskoka lakes. Dispros have made a unique contribution to North American pleasure-boating history.


    Communément appelé le « Dispro » ou « Dippy », ce petit bateau est construit ici pour la première fois en 1916 par la Disappearing Propeller Boat Company Limited. Il est également fabriqué dans d'autres régions de l'Ontario et brièvement aux États-Unis. En tout, plus de 3 000 embarcations de ce type sont construites et vendues dans le monde entier avant l'arrêt de la production en 1956. À l'origine, le constructeur de bateaux W.J. Johnston Jr. et le machiniste Edwin Rogers inventent un dispositif qui permet à l'hélice et à son arbre de se replier manuellement ou automatiquement dans un boîtier de protection pendant que le moteur est en marche. Ce système breveté assure une protection contre les rochers cachés sous la surface des lacs du Bouclier canadien. Construits en plusieurs modèles de 4,9 mètres à 5,8 mètres (de 16 pieds à 19 pieds), les bateaux sont faits de planches de cyprès superposées et fixées aux nervures de chêne assouplies à la vapeur. La plupart sont dotés d'un moteur monocylindrique de trois chevaux-puissance. Simples, versatiles et résistants, ces bateaux étaient nombreux à sillonner les eaux des lacs Muskoka. Les bateaux à hélice escamotable ont contribué de façon unique à l'histoire de la navigation de plaisance en Amérique du Nord.

Historical background

The Disappearing Propeller Boat — popularly known as the “DP,” “Dippy” or “Dis-pro” — was a unique Canadian contribution to North American pleasure-boating history. Developed in the early years of motorized recreational boating, it was manufactured — unchanged save for minor details — for more than four decades, finally going out of production permanently in 1958. Approximately 250 to 300 out of a total estimated production run of 3,100 have survived to the present day. Restored, repaired and cherished by their owners, they can be seen in museum collections and at antique and classic boat shows across North America.

As with many unique watercraft forms, the Dis-pro was a response to particular circumstances, in this case an existing lapstrake boatbuilding tradition, a burgeoning tourism economy with its attendant hotels, railways and transportation needs, an emerging market for owner-operated (as distinct from professionally crewed) motorized pleasure boats, and Canadian Shield lakes with frequent rocky outcroppings not far below the surface. The boat is a combination of a conventionally constructed lapstrake hull, which links it to any number of vernacular small craft in Europe and North America, an early 20th-century marine power plant and what is colloquially known as "the device," the haul-up arrangement of the driveshaft, propeller and rudder. Other forms of powered small watercraft exhibit adaptions for shallow and/or obstructed waters, including tunnels or concavities in the bottom to reduce the draft of the running gear or a universal joint in the shaft as seen on some Grand Banks dories fitted with what were known as "haul-ups." The Dis-pro was unique in that the large skeg in front of the propeller meant that the running gear would kick itself up into the aluminum housing in the hull if it met an obstruction with the motor still running, whereas the dory haul-up could only be operated when the engine was stopped.

In the last quarter of the 19th century, rising middle-class wealth, a shortening work week, advances in technology and the advent of widespread rail networks gave rise to a leisure economy in many areas of North America. In Ontario, areas such as the land around the Rideau Canal, the Kawarthas and the Muskoka Lakes all began to receive traffic from visitors and tourists. In the Muskoka Lakes in particular, as the dominant activities in the region’s economy began a transition from farmsteading and resource extraction to recreation, the burgeoning tourist trade was fed by the construction of substantial hotels to accommodate visitors who arrived by rail. Once there, they availed themselves of rental fleets of rowing skiffs offered by hotels and liveries.

Internal combustion-powered pleasure boats began to appear in the Muskoka area at the end of the 19th century, and Ditchburn, later to become a major builder of high-end mahogany runabouts, was building gasoline launches by 1898. A significant concentration of boatbuilders began to develop, paralleling the focus on canoe building in the Peterborough area to the east.

Early Muskoka pleasure boats were paddled, rowed or powered by steam or naptha engines. While the latter two powerplants could take small boats farther and faster, naptha and steam powerplants were expensive, complex, potentially hazardous and, in the case of steam, required certification to operate safely. When the first practical marine internal combustion engines appeared in the early 1890s, boatbuilders were quick to use and market them as improvements over steam and naptha, touting their safety and relative simplicity. These early internal combustion engines were heavy for their power output, and the hulls developed to accommodate them were long, narrow, easily driven forms known as “launches.”

The Dis-pro began as an innovation that married an early inboard to the hull of a typical rowing skiff, such as was in use by hotel liveries. The Johnston rowing skiff, which inspired the new boat, was similar in underwater form to the early power launches — long, narrow and sharp at both bow and stern. When the Dis-pro device was added, the engine was positioned just forward of amidships and the propeller exited through the keel in the after-half of the boat.

Another option for motorizing heretofore human-powered watercraft hull forms was demonstrated by the St. Lawrence Skiff of the Thousand Islands region. Like the Dis-pro, it too arose from resort culture as railroads and hotels brought in tourists and visitors. The St. Lawrence Skiff originated as a working boat for fishing guides, which, at a typical length of 18 to 20 feet, was somewhat longer than the under-15-foot Johnston rowing skiff. When engines were fitted to these boats, the propeller shaft exited through the stern post, creating a new form called the “skiff-putt.”

What makes the Dis-pro unique in the history of North American pleasure boating, however, is how it did and did not evolve. The St. Lawrence Skiff hulls progressed from a midships engine installation in the existing sharp-sterned hull, to truncating the stern into a small transom without materially changing the hull shape, to changing the hull shape to provide more bearing aft and prevent squatting, leading eventually to the development of the broader-sterned planing hull.

In the case of the Dispro, because of the unique powertrain installation, this innovation in hull shape, occasioned for the most part by fitting larger and more powerful engines for which the hull needed to be adapted, was stopped in its earliest phase and the type continued unchanged long past the point at which it represented current practice. Beloved by its owners, tolerated and even celebrated for its eccentricities, it survived as a remarkable anachronism, still produced and sold into the middle of the post-war boating boom of the 1950s. By the time Greavette made the last Dis-pro in 1958, the rest of the pleasure boating world had long since become obsessed with planing hulls, powerful inboards and outboards and a host of new materials including plywood, fiberglass, aluminum and laminated wood.

The Dis-pro is also noteworthy because the Waterman company, source of the first engines installed in Dis-pros, was also a pioneering maker of outboard engines. Its first outboard patent was awarded in 1905, four years before the better-known Evinrude engines were created. Even though the Waterman was relatively short-lived as an outboard marque, the transom-sterned outboard-powered boats it made possible would, in time, become some of the Dis-pro’s main competitors in the market for small utility pleasure craft.

The design and manufacturing history of the Dis-pro is addressed at length in the definitive work on the subject: The Greatest Little Motorboat Afloat: The Legendary Disappearing Propeller Boat. Erin, ON: Boston Mills Press, 1983. Interested readers are invited to consult this book and/or visit the Muskoka Lakes Museum in Port Carling, where they can see a Dis-Pro on display.

The Ontario Heritage Trust gratefully acknowledges the research of Natasha Henry in preparing this paper.

© Ontario Heritage Trust, 2015


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