While on a normal tow, the COASTAL DRILLER is threatened with the approach of a severe storm. The legs should be lowered so that the TOC (tip-of-can) is lowered from 1.20 feet to __________.
• Jack-up rig operating limits in severe weather • How lowering the legs changes the tip-of-can (TOC) air gap • Typical safe air gap (distance from TOC to waterline) during a storm on tow
• Think about whether the TOC should end up closer to or farther from the water when preparing for a severe storm on tow. • Compare the answer choices: which ones are small changes from 1.20 ft, and which are large changes? What would be the purpose of a large change? • Consider what happens to stability and wave clearance if the TOC is only slightly deeper versus much deeper below the surface.
• Verify whether storm procedures on tow aim to increase or decrease the TOC submergence. • Check which options are realistic changes from 1.20 ft for a jack-up’s leg and can spacing during a storm (think in terms of feet vs tens of feet). • Ensure the final TOC depth is consistent with the idea of providing adequate clearance from wave action and improving tow stability.
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