A Solution to the Inherent List on Nimitz Class Aircraft Carriers

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4.0 Conclusion Solid ballast is <strong>the</strong> most advantageous solution for correcting <strong>the</strong> inherent list on <strong>the</strong> Nimitz class aircraft carriers. Table 6 illustrates that <strong>the</strong>re are a number of advantages and disadvantages that must be considered when determining <strong>the</strong> proper location for <strong>the</strong> Perma Ballast®. • The 2" deck is <strong>the</strong> choice location for list corrections at or beyond 1.5 degrees. The costs associated with adding ballast <strong>to</strong> <strong>the</strong> 2"^^ deck is much higher, but <strong>the</strong> amount of ballast required is significantly less than that required for <strong>the</strong> 4'^ and 8 decks. o Advantages: ■ significantly less weight added o Disadvantages: ■ more costly ■ increased KG* • For list corrections less than 1.5 degrees, <strong>the</strong> choice location is <strong>the</strong> S'*' deck. Less than 1.5 degrees, <strong>the</strong> 2"'' and 8"" decks have a fairly comparable weight addition, however, ballasting <strong>the</strong> 8'*' deck tanks costs significantly less. o Advantages: ■ significantly less costly ■ decreased KG* o Disadvantages: ■ increased weight addition th *Any positive change in KG serves <strong>to</strong> reduce <strong>the</strong> remaining KG service life allowance. The average KG service life allowance remaining for most carriers is approximately 1.5 feet. Even <strong>the</strong> greatest list correction of 3 degrees is only a 7% reduction in <strong>the</strong> remaining KG service life allowance for <strong>the</strong> aircraft carriers. 50
5.0 Recommendations 1. As can be seen in Table 1, most of <strong>the</strong> Nimitz class aircraft carriers currently have an average list of approximately 1.5 degrees. It is recommended that <strong>the</strong> ships be ballasted on <strong>the</strong> T^ deck at this point <strong>to</strong> avoid adding excess ballast as mentioned previously. The cost is approximately 22% higher, but <strong>the</strong> weight addition is approximately 28% less. This is a considerable amount of weight reduction. The displacement service life allowance must also be analyzed. If you assume a contract displacement of 100,000 long <strong>to</strong>ns with a 5% service life displacement allowance for an in-service carrier, <strong>the</strong>n 400 long <strong>to</strong>ns <strong>to</strong> correct 1.5 degrees of inherent list would be less than 1/10 of <strong>the</strong> service life (100,000 * .05 = 5,000 I<strong>to</strong>ns and 400 / 5000 is approx. 8%). This can be viewed as a significant change in displacement or a relatively small change in displacement when looking at all <strong>the</strong> advantages that come with correcting <strong>the</strong> inherent list on <strong>the</strong> Nimitz class carriers. Also, <strong>the</strong> cost per I<strong>to</strong>n for a 1.5 degree list correction is approximately $1,200. This is truly inexpensive from a survivability standpoint and also reduces <strong>the</strong> operational constraints placed on <strong>the</strong> ship. 2. The prudent manner in which <strong>to</strong> handle <strong>the</strong> inherent list associated with each aircraft carrier is <strong>to</strong> perform an inclining experiment on each carrier. The inclining experiment data can <strong>the</strong>n be used <strong>to</strong> assess <strong>the</strong> amount of ballast necessary for installation and can be conducted when each ship's operational schedule will permit it. As mentioned previously, much of <strong>the</strong> data for each carrier has been extrapolated from re-evaluation of <strong>the</strong> results of <strong>the</strong> CVN 71 Displacement Test and <strong>the</strong> CVN 68 Post-RCOH inclining experiment. Knowing that <strong>the</strong>se tests are extremely expensive and that CVN 71-75 are <strong>the</strong> carriers in need of list correction, perhaps an inclining experiment could be performed on one of <strong>the</strong>se carriers so that data could <strong>the</strong>n be extrapolated fur<strong>the</strong>r. 51
Page 1 and 2: A Solution <strong
Page 3 and 4: A Solution <strong
Page 5 and 6: Table of Contents Abstract 3 Acknow
Page 7 and 8: 1.0 Introduction 1.1 Motivation Air
Page 9 and 10: class. Changes to
Page 11 and 12: classified into fo
Page 13 and 14: o Control the KG g
Page 15 and 16: the intact stabili
Page 17 and 18: for ships propulsion, respectively.
Page 19 and 20: combined with the
Page 21 and 22: 1.3.7 Ballast Addition 1.3.7.1 Wate
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Page 25 and 26: Tank name Tank volume Ballast type
Page 27 and 28: was successfully performed and <str
Page 29 and 30: of each tank's location was added,
Page 31 and 32: 2.3 Preliminary Decision-Making Cos
Page 33 and 34: All further costin
Page 35 and 36: 2.4 Structural Analysis One tank on
Page 37 and 38: this pressure. This resulted in a r
Page 39 and 40: 2.4.1 Structural Modifications 2.4.
Page 41 and 42: Main Deck Shell FR 165 - FR 180 Tra
Page 43 and 44: 2.4.1.3 Modifications to</s
Page 45 and 46: 3.1 Final POSSE Results The minimum
Page 47 and 48: Table 6: Final Cost, Weight Additio
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Design of Plating for Surface Ships
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Calculations to De
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structural Analysis for Compartment
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Resulting Pressure on Shell Plating
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Stress Calculations for 227 I<stron
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Resulting Pressure on Inner Longitu
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Resulting Pressure on Transverse Bu
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A Solution to the Inherent List on Nimitz Class Aircraft Carriers

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