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4 EARLY GREAT LAKES STEAMBOATS The First Propellers 1841-1845 by H. A. Musham The year 18^+0 marked the opening of a new era in steam navigation.The decade that followed was a period of experiments, trials, and errors, and especially so on the lakes. While the steamboats there had reached a relatively high level of efficiency consistent with the shipbuilding materials and propelling machinery then available, there was much room for improvement in them. They were all built of wood, and, with the exception of a few stern-wheelers used in rivers and canals, were all sidewheelers. Both high-and low-pressure engines of various types were used, the walking-beam type predominating. The boilers were generally of the fire-tube type with large flues running from end to end. These varied in size and number, some boats having as many as seven. Steam pressure seldom exceeded fifteen pounds per square inch. The engines made up to twenty-five revolutions per minute. Some boats had two engines, each turning a wheel independently of the other.Wood was the only fuel burned. While coal had been brought to the lakes, it was too high in price and not widely enough distributed as yet to make its use practicable. The speed attained seldom exceeded the limit for economical operation(l). This for the largest boats was from ten to twelve miles an hour. The steamboats, especially those with decks built out on guards running from stem to stern and enclosing the side wheels, were well adapted to carrying passengers. But they were not so well suited for freight. The cubic capacity of the molded form (2) was reduced from fifteen to twenty percent by the frames, planking, ceiling, posts, knees, and keelsons of the hull structure. Add to this the over-large space taken up by the engines, boilers, and woodbins amidships - the most capacious part of the hull-and the space occupied by the passenger accommodations below the main deck, that left for freight was but a small part of the form. Again the excessive weight of the wooden hulls and cf the large, slow - moving engines reduced the carrying capacity by weight materially. The engines were practically all single - crank affairs with no means provided to balance their turning. On the upstroke, the piston speed slacked somewhat, on the down it accelerated, and the boat moved forward in surges. Side wheels attain their highest efficiency when the floats are immersed to an optimum depth. The desideratum of the ship and engine builders was to place the wheels vertically so that immersion was attained when the boat was at the load draft and at such point a-long the side, that they did not turn in the hollow of the bow waves set up by the boat at full speed. When the boat was in light condition, the immersion of the floats was less than desired and a decrease in speed resulted. When it was over the load draft, the wheels churned the water around and another loss in speed was the result. In heavy weather, rolling caused unequal immersion from side to side and the boat yawed and wobbled along on its course. Then when going into a head sea, the immersion again varied as the waves raced along the sides. This accentuated the surging of the boat. Rolling, pitching, and the surging of the engine produced a most uncomfortable motion in the boat to the discomfort of the crew and passengers. Added to these disadvantages was the vulnerability of the side wheel when applied to the warships of the day. With a large part of their machinery above the water line and the wheels exposed to direct gunfire, they were likely to be quickly put out of action no matter what position they could take when engaging the enemy. There was but one answer to these problems and that was propulsion by submerged wheels, smaller engines for the same power, placed lower down in the hulls, and iron hulls, The idea of propulsion by submerged wheels was not new. Two ways of using them had been set forth by inventors and engineers, by the screw propeller and the horizontal paddle wheel. The screw propeller is an an-