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Suggested Citation:"Appendix E." National Research Council. 1998. Double-Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990. Washington, DC: The National Academies Press. doi: 10.17226/5798.
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APPENDIX E Supplementary Data on Vessel Ownership for the U.S. Trading Fleet

Table E-1 shows the change in age from 1990 to 1994 on the basis of ownership category for vessels in the U.S. trading fleet. For government-owned vessels there was an increase in age of 0.38 year, but this was more than offset by the decrease of 1.02 years in the age of the numerous independent fleet and 0.99 year in the small oil company fleet. When figures based on the number of port calls are considered, rather than just the fleet itself, as shown in Table E-2, the change is more pronounced: 1.66 years average reduction, with a 0.35-year decrease for governments, a 1.49-year decrease for independents, and a 2.51-year decrease for oil companies. The new vessels are clearly making more calls on average than the older ones.

TABLE E-1 Changes in Age of the U.S. Trading Fleet Based on Individual Ships by Ownership Category, 1990-1994

 

Government

Independents

Oil Companies

Age Range

1990

1994

Change

1990

1994

Change

1990

1994

Change

0-4

1.83

1.78

-0.05

2.23

2.07

-0.16

2.46

1.75

-0.71

5-9

7.53

7.53

0.00

7.48

6.75

-0.73

8.01

6.46

-1.55

10-14

12.59

11.65

-0.94

12.58

12.41

-0.17

12.16

12.41

+0.25

15-19

15.00

17.18

+2.18

16.00

17.60

+1.60

16.06

17.63

+1.57

20-24

 

 

 

20.48

20.74

+0.26

20.87

20.52

-0.35

25 or more

 

 

 

35.97

33.44

-2.53

30.45

37.67

+7.22

Average

9.05

9.43

+0.38

11.55

10.53

-1.02

13.50

12.51

-0.99

Suggested Citation:"Appendix E." National Research Council. 1998. Double-Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990. Washington, DC: The National Academies Press. doi: 10.17226/5798.
×

TABLE E-2 Changes in Age of the U.S. Trading Fleet Based on Port Calls by Ownership Category, 1990-1994

 

Government

Independents

Oil Companies

Age Range

1990

1994

Change

1990

1994

Change

1990

1994

Change

0-4

2.13

2.39

+0.28

2.22

2.04

-0.18

2.46

1.65

-0.81

5-9

7.98

7.51

-0.47

7.64

6.79

-0.85

8.01

6.53

-1.48

10-14

12.29

11.79

-0.50

12.43

12.53

+0.10

12.16

12.34

+0.18

15-19

15.00

17.26

+2.26

15.90

17.49

+1.59

16.06

17.58

+1.52

20-24

 

 

 

20.87

20.97

+0.10

20.87

20.41

-0.46

25 or more

 

 

 

36.24

34.16

-2.08

30.45

37.14

+6.69

Total

9.10

8.85

-0.35

11.64

10.15

-1.49

12.92

10.41

-2.51

In looking beyond averages at size categories, it can be seen that the average age of government vessels has been decreasing for smaller vessels (<150,000 DWT [deadweight tons]) and becoming more diverse for larger vessels (> 150,000 DWT). The same broadly applies to oil companies. Independents show a split tendency, with old and young ships predominating in large sizes but few in the middle age bands, and a broad balance in the smaller sizes (see Table E-3).

Suggested Citation:"Appendix E." National Research Council. 1998. Double-Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990. Washington, DC: The National Academies Press. doi: 10.17226/5798.
×

TABLE E-3 Size in Million DWT of the U.S. Trading Fleet by Age Range and Ownership Category, 1990 and 1994

 

Government

Independents

Oil Companies

 

0-150,000 DWT

> 150,000 DWT

0-150,000 DWT

> 150,000 DWT

0-150,000 DWT

> 150,000 DWT

Age Range

1990

1994

1990

1994

1990

1994

1990

1994

1990

1994

1990

1994

0-4

0.34

1.98

0

2.61

9.93

27.91

3.93

7.90

0.89

3.42

0.15

0.28

5-9

1.25

1.58

0

0.61

12.91

13.55

2.99

1.62

2.05

1.19

0.26

0

10-14

0.65

0.95

1.71

0.59

17.12

14.74

17.12

1.45

2.60

1.32

7.28

0

15-19

0.22

1.30

0

2.10

17.96

17.56

18.72

21.79

3.51

1.87

10.99

3.66

20-24

 

 

 

 

2.04

4.70

0

5.23

0.16

1.62

0.31

3.50

25 or more

 

 

 

 

0.69

0.92

0.90

0

0.20

0.14

0.27

0

Total

2.46

5.81

1.71

5.91

60.65

79.38

43.64

37.99

9.41

9.55

19.25

7.45

Suggested Citation:"Appendix E." National Research Council. 1998. Double-Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990. Washington, DC: The National Academies Press. doi: 10.17226/5798.
×
Page 173
Suggested Citation:"Appendix E." National Research Council. 1998. Double-Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990. Washington, DC: The National Academies Press. doi: 10.17226/5798.
×
Page 174
Suggested Citation:"Appendix E." National Research Council. 1998. Double-Hull Tanker Legislation: An Assessment of the Oil Pollution Act of 1990. Washington, DC: The National Academies Press. doi: 10.17226/5798.
×
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The passage of the Oil Pollution Act of 1990 (OPA 90) by Congress and subsequent modifications of international maritime regulations resulted in a far-reaching change in the design of tank vessels. Double-hull rather than single-hull tankers are now the industry standard, and nearly all ships in the world maritime oil transportation fleet are expected to have double hulls by about 2020.

This book assesses the impact of the double hull and related provisions of OPA 90 on ship safety, protection of the marine environment, and the economic viability and operational makeup of the maritime oil transportation industry. The influence of international conventions on tank vessel design and operation is addressed. Owners and operators of domestic and international tank vessel fleets, shipyard operators, marine architects, classification societies, environmentalists, and state and federal regulators will find this book useful.

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