A Solution to the Inherent List on Nimitz Class Aircraft Carriers

More documents

Recommendations

Info

<strong>the</strong> vessel <strong>to</strong> be ballasted and its location. Requirements such as electrical, water, compressed air, and equipment location are assessed. BTI engineers <strong>the</strong>n submit engineered drawings noting location of equipment and diagrams of <strong>the</strong> installation system along with a written operating plan for <strong>the</strong> project. BTI uses its own experienced personnel and equipment during ballast installations <strong>to</strong> ensure safe, rapid and efficient mobilization, installation, and demobilization. BTI's ballast materials are mixed with water and pumped <strong>to</strong> <strong>the</strong> vessel via a combination of rigid and flexible pipes. The slurry is pumped in at a controlled velocity in order <strong>to</strong> assure an even distribution of <strong>the</strong> ballast around projections, pipe, and o<strong>the</strong>r objects, leaving no voids. Excess water is removed as <strong>the</strong> ballast is installed and settles. This ensures that <strong>the</strong> in-place, fixed ballast is a dense mass which will not move or shift. Due <strong>to</strong> BTI's materials and placement method, no special handling or tank modifications are required. BTI pretests materials in its labora<strong>to</strong>ry <strong>to</strong> ensure proper density and uniformity. Continuous testing is performed during ballast installation <strong>to</strong> verify installed density. Densities of materials range from 1501b/ft^ <strong>to</strong> 3501b/ftl All processes and materials used by BTI are approved by ASTM, ABS, MARAD, U.S. Navy, U.S. Coast Guard, Del Norske Veritas, and Lloyds. In fact, Perma Ballast® has already been installed on a number of naval vessels, particulariy DDG 73,76, and 77. The reason for installation was <strong>to</strong> correct a Flight II starboard list. Feedback obtained from <strong>the</strong>se installations described <strong>the</strong> process as being very smooth and extremely successful. There are a number of advantages <strong>to</strong> using this Perma Ballast®. It is possible that Perma Ballast® will absorb shock over a limited area and serve <strong>to</strong> dampen it. Although <strong>the</strong> individual particles and <strong>the</strong> water are incompressible, <strong>the</strong> Perma Ballast® bed is made up of many very small particles which are not bound <strong>to</strong>ge<strong>the</strong>r by anything except gravity. There is approximately 22
2% entrained air (by volume) in <strong>the</strong> slurry. Some of this air probably remains in <strong>the</strong> slurry after settling so it would be fair <strong>to</strong> say that Perma Ballast® contains about 1-2% (by volume) compressible components. Water is removed as <strong>the</strong> material settles, but even after <strong>the</strong> Perma Ballast® settles, all of <strong>the</strong> voids between particles are filled by water. In fact, a settled bed of Perma Ballast® is an extremely effective barrier against permeation of oxygen - ei<strong>the</strong>r in<strong>to</strong> <strong>the</strong> bed or through it. 1.4 Option Selection From <strong>the</strong> options presented above, <strong>the</strong> choice was made <strong>to</strong> use solid ballast <strong>to</strong> correct <strong>the</strong> starboard inherent list on <strong>the</strong> Nimitz class carriers. Based on ballast density, tank location and capacity, ease of ballast installation, minor tank structural modifications, and a decision making cost analysis, <strong>the</strong> Perma Ballast® appears <strong>to</strong> be <strong>the</strong> best option for use in correcting <strong>the</strong> inherent list on <strong>the</strong> Nimitz class aircraft carriers and is discussed extensively in Chapter 2. 2.0 Preliminary Analysis and Results Preliminary analysis began with tank selection <strong>to</strong> serve as input <strong>to</strong> <strong>the</strong> Program of Ship Salvage and Engineering (POSSE) computer analysis program, discussed later in section 2.2. Once tanks were selected for ballasting, a naval architectural analysis using POSSE was performed for 36 scenarios <strong>to</strong> determine list corrections. These scenarios encompassed ballasting on <strong>the</strong> 2°'', 4*, and 8* decks with 200 Ib/ft^ and 325 Ib/ft^ density ballast. Fresh water was also examined as a possible alternative, but not as extensively as <strong>the</strong> solid ballast option. Once a complete set of data was obtained, a decision making cost analysis was performed. This cost estimation analysis proved that <strong>the</strong> 200 Ib/ft^ density ballast was <strong>the</strong> best option. As a result, all structural analysis was performed using <strong>the</strong> 200 Ib/ft^ density ballast. Once <strong>the</strong> structural analysis was complete, modeling had <strong>to</strong> be performed again using POSSE. In some cases, a 23
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: 1.3.7 Ballast Addition 1.3.7.1 Wate
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
Page 49 and 50: Corrosion coupons are placed in all
Page 51 and 52: 5.0 Recommendations 1. As can be se
Page 53 and 54: References [I] Design Data Sheet 07
Page 55 and 56: O CO ■*. CM d CVI d CVI d CO d CO
Page 57 and 58: 1
Page 59 and 60: ■ • s*; eo 1 CM ■
Page 61 and 62: ■ E 1- < O Y < ^^ i SS! m c in in
Page 63 and 64: ON OC) 00 00 o o o ^ < ^ < o 00 o I
Page 65 and 66: «n < 1-H ON H ^ 0\ 1—1 i-( o ©
Page 67 and 68: in -^J r-- OS H 00 ■* ri o F^^ ^
Page 69 and 70: =» * o o o o o o o § § < S , , s
Page 71 and 72: i V) H % * l-H
Page 73 and 74:
% H o o o © s * < © © o i^ © H
Page 75 and 76:
* * H o o o o o o o o o e o o O o o
Page 77 and 78:
M t» c« * ft ft H ft 00 O 00 r- O
Page 79 and 80:
1^ r-( 1-H M n
Page 81 and 82:
Vi ^■ ««■ -^ ^^ * * o o o o o
Page 83 and 84:
4t S C/l r/i 00 * s M * o * < ly) C
Page 85 and 86:
^5- Q © © © © © © o o © ©
Page 87 and 88:
"~" ~ 00 s ^ SS o s ■g Q ■* ja
Page 89 and 90:
structural Analysis for Compartment
Page 91 and 92:
Resulting Pressure on Sponson Plati
Page 93 and 94:
Calculations to De
Page 95 and 96:
Stress Calculations: k = coefficien
Page 97 and 98:
Page 99 and 100:
FR 165 - FR 180 Transverse Bulkhead
Page 101 and 102:
Design of Plating for Surface Ships
Page 103 and 104:
Page 105 and 106:
Main Deck Shell FR 165 - FR 180 Tra
Page 107 and 108:
Calculations to De
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Calculations to De
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Calculations to De
Page 121 and 122:
Stress Calculations: Stiffening k =
Page 123 and 124:
Resulting Pressure on Shell Plating
Page 125 and 126:
Calculations to De
Page 127 and 128:
Stress Calculations for 227 I<stron
Page 129 and 130:
Resulting Pressure on Inner Longitu
Page 131 and 132:
Calculations to De
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Stress Calculations k = coefficient
Page 139 and 140:
Resulting Pressure on Transverse Bu
Page 141 and 142:
Calculations to De
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
__ — __ — """ " *c; 1— ai S s
Page 151 and 152:
o ON H 00 ^ ^ o > o -o B u H r^ 00
Page 153 and 154:
MATERIAL WORK SHEET PERMA BALLAST®
Page 155 and 156:
*• en * 5fc M S 00 00 * yj c« 1/
Page 157 and 158:
CO 5t CO 00 en St 0\ CO 5t o © St
Page 159:
* CO * * vT 00 * in r4~ vT * cr C/l
show all

A Solution to the Inherent List on Nimitz Class Aircraft Carriers

Create successful ePaper yourself

Delete template?

Save as template?