By this test leaks are located that cannot be detected in any other way, and the explorer during his voyage is saved the maddening annoyance of listening to the trickling of incoming water as he lies in his bunk at night, of the daily clank of the pumps, and of a ship with bilges full of ice at the end of the Polar winter.
In regard to engine power, my ideas have been radically different from those of other navigators. I have believed in all the power it was possible to get into the ship. I know of few more comfortable feelings for the commander of a ship beset in the ice than the knowledge that he has beneath his feet the power that with the least slackening of the ice pressure will enable him to force his ship ahead on her course.
The motive power of the Roosevelt consisted of a single, inverted, compound engine, capable of developing a thousand horse-power, and driving an eleven-foot four-blade propeller. Two water-tube boilers and one Scotch boiler supplied steam.
Two specially distinctive features of the machinery of the Roosevelt were a large “by-pass,” by means of which, by turning a valve, steam from all the boilers at full pressure could be turned directly into the big fifty-two-inch low-pressure cylinder, more than doubling the power for a short time; that is, as long as the boilers could meet this excessive demand. The object of this was to give me a reserve of power with which to extricate the ship from a particularly dangerous position. On at least two occasions this device accomplished all that was expected of it, and, by resistlessly forging the ship ahead a length or two against all odds, removed her from the line of deadly pressure, and so saved her.
STERN OF “ROOSEVELT” IN DRY DOCK
Note rounded curves, massiveness of propeller, skeg and rudder, and lavish use of steel plates. Rudder is of white oak timbers 16 in. × 16 in.
The other was an enormously heavy and strong propeller and shaft. The shaft was a twelve-inch diameter solid steel forging, a shaft big enough for a 2000-ton tramp steamer. The propeller was correspondingly heavy. The object of this was to prevent the complete crippling of the ship by breaking of shaft or propeller.
This idea entailed unusual weight and expense, but it served its purpose and was never regretted.
When in July, 1906, the Roosevelt was smashed against the unyielding ice-foot at Cape Union, tossed about like an egg-shell, and treated generally as if she were of no account, a particularly vicious corner of an old floe struck her astern, broke one propeller-blade square off, tore off the ponderous white-oak skeg, or after stern-post, and, catching under propeller and projecting end of shaft, lifted the whole after part of the ship as a man would lift a wheel-barrow, until her heel was out of water, and held her in this way for several hours until the tide changed. Had propeller and shaft been of usual proportions, neither would ever have made another revolution. As it was, my twelve-inch shaft was not even thrown out of line, and barring the broken propeller-blade, the machinery suffered no damage.