An exploratory investigation of a free fall submersible escape capsule for an offshore oil rig

Goteti, Raju (1988) An exploratory investigation of a free fall submersible escape capsule for an offshore oil rig. Masters thesis, Memorial University of Newfoundland.

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    Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
    (Original Version)

Abstract

The Ocean Ranger and other oil rig disasters have shown that rig evacuation systems often do not work properly during severe storms. Most make use of cables to lower the survival craft to the ocean surface. In stormy weather, a pendulum-like motion of the craft can develop causing it to crash into the rig structure. Even when a craft reaches the ocean surface intact, thigh winds and waves can drive it against rig structures near the waterline. A fee fall submersible capsule system is proposed in this thesis which could avoid these problems. Upon release from the rig, the capsule would fall freely to the ocean surface. It would then sink into the ocean down to a level where water motion is insignificant. -- Obviously, there are many factors that would have to be considered for a complete investigation of such a system. Some of these are: the release mechanism, the free fall in gale force winds, the impact of the capsule onto the ocean surface, the post impact trajectory beneath the surface, the capsule recovery and the life support systems. This thesis examines only the impact and control aspects of the evacuation. Experimental data are presented which show that the decelerations experienced by a capsule when it impacts the ocean surface are well within human tolerance limits. Also, experimental data are presented which show that at model scale submergence depth of a capsule can be adequately controlled. This is in spite of the fact that the model constructed had severe hardware limitations. Obviously, with better hardware, much better control should be possible. The describing function concept of classical control theory explained much of what was seen in the depth control experiments.

Item Type: Thesis (Masters)
URI: http://research.library.mun.ca/id/eprint/5276
Item ID: 5276
Additional Information: Bibliography: leaves 61-62.
Department(s): Engineering and Applied Science, Faculty of
Date: 1988
Date Type: Submission
Library of Congress Subject Heading: Offshore structures--Safety measures; Drilling platforms--Safety measures; Lifeboats

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