For water propulsion, the most common types are underwater propeller, water jet, paddle wheel and, experimentally, magneto-hydrodynamic. Sails are also common, and historically represented the most significant form of early propulsion for large watercraft. Paddles or oars were probably the earliest form of water propulsion.
For ground propulsion, virtually all of the above have been used at one time or another. Most ground vehicles use wheels of one sort or another, but the power plant used to drive them can vary widely. In modern times, most vehicles use some form of internal-combustion engine, with electric motors supplementing them. Historically, vehicles were drawn by animals or driven by steam.
For these and other types of transportation, see transport.
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One construction method for burying offshore pipelines utilizes a segmented excavation shield for forming a trench in the seafloor.
The primary purpose of the present invention is to provide a method and apparatus for the propulsion of a marine pipeline excavation shield, which greatly reduces the power requirements normally necessary to move the apparatus and which thereby saves construction time.
Advantages of the "inch-worm" method are, (1) there is no limiting size; the method can be scaled up as required to accommodate pipe and trench geometry; (2) there is a minimum of moving parts; and (3) a reverse control sequence permits the unit to back up.
In the method utilizing the apparatus, the anode compartment and cathode compartment are supplied with moist hydrogen and moist oxygen, respectively, so as to substantially suppress the evolution of gas in the duct, which lowers the thrusting force.
An underwater propulsion apparatus as defined in claim 1, said apparatus further comprising water electrolysis means for electrolyzing water to produce the moist hydrogen gas and the moist oxygen gas which are supplied to said anode compartment and said cathode compartment, respectively.
The method further comprises the steps of electrolyzing water to produce hydrogen gas and oxygen gas, and supplying the hydrogen gas and the oxygen gas to the electrodes, the hydrogen gas being supplied to an anode of the electrodes and the oxygen gas being supplied to a cathode of the electrodes.
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