While in 150 feet water depth when the pitch angle of the COASTAL DRILLER is 1 degree, the platform pitch period for going on location should be longer than __________.
• Pitch period of a semi-submersible or drilling unit and how it relates to safe operations when going on location • Effect of water depth (150 ft) on the motion characteristics of a floating platform • Typical time scales (in seconds) for pitch motions versus very fast or very slow vessel motions
• Compare the given pitch angle (1 degree) and water depth (150 feet) to what you know about how quickly large offshore units normally pitch—are their motions fractions of a second, or several seconds? • Think about which of the answer choices are clearly unrealistically short or long for a large platform’s pitch motion. • Ask yourself: when operators specify a minimum safe pitch period, are they usually concerned about avoiding very rapid motions, or very slow ones?
• Eliminate any pitch periods that are so short they would imply extremely rapid, almost vibrating motions for a large platform. • Consider which values fall into a realistic period range for a large floating unit’s pitch motion. • Verify which option would represent a period that is safely on the slower side of typical pitch motions, providing a more stable condition for going on location.
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