| 摘要 |
A hollow generally circular horizontal float body is provided. The body tapers in thickness from its central portion of its outer periphery and includes upper and lower walls which are inclined downwardly and upwardly, respectively, from the central portion to the outer periphery of the body. A horizontal work platform is spaced above the body and supported therefrom by upstanding supports extending and secured between the body and the platform at points spaced about the central portion of the body. The body includes a central vertical passage therethrough and the interior of the body spaced outwardly of and about the central portion includes structure defining ballast tanks which may be selectively flooded and evacuated of water. A central upstanding caisson is supported at its upper end from the body about the passage and the caisson comprises a plurality of relatively telescopingly engaged tubular sections wih the lower section provided with flotation structure selectively operable for buoying the lower section upwardly toward a retracted position and each successive section of the caisson above the lower section thereof is engageable by the lower section thereunder in order that it may also be buoyed upwardly toward a retracted position. The extreme outer periphery of the body defines an airtight buoyancy chamber spaced outwardly of the ballast tanks and the body, after being properly positioned above a given location of the ocean floor engaged by the lower end of the caisson, includes anchor structure whereby the float body may be anchored in the desired position.
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