46 CFR § 42.20-60 - Deduction for superstructures and trunks.
(a) Where the effective length of superstructures and trunks is 1.0L, the deduction from the freeboard shall be 14 inches at 79 feet length of vessel, 34 inches at 279 feet length, and 42 inches at 400 feet length and above; deductions at intermediate lengths shall be obtained by linear interpolation.
(b) Where the total effective length of superstructures and trunks is less than 1.0L the deduction shall be a percentage obtained from table 42.20–60(b)(1) or table 42.20–60(b)(2):
Table 42.20–60(b)(1)—Percentage of Deduction For Type “A” Vessels
| Total effective length of superstructures and trunks | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 0.1 |
0.2 |
0.3 |
0.4 |
0.5 |
0.6 |
0.7 |
0.8 |
0.9 |
1.0 |
|
| Percentage of deduction for all types of superstructures 1 | 0 | 7 | 14 | 21 | 31 | 41 | 52 | 63 | 75.3 | 87.7 | 100 |
1 Percentages at intermediate lengths of superstructures and trunks shall be obtained by linear interpolation.
Table 42.20–60(b)(2)—Percentage of Deduction for Type “B” Vessels
[Percentage of deduction1]
| Total effective length of superstructures and trunks | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Line | 0 | 0.1 |
0.2 |
0.3 |
0.4 |
0.5 |
0.6 |
0.7 |
0.8 |
0.9 |
1.0 |
|
| Vessels with forecastle and without detached bridge | I | 0 | 5 | 10 | 15 | 23.5 | 32 | 46 | 63 | 75.3 | 87.7 | 100 |
| Vessels with forecastle and detached bridge | II | 0 | 6.3 | 12.7 | 19 | 27.5 | 36 | 46 | 63 | 75.3 | 87.7 | 100 |
1 Percentages at intermediate lengths of superstructures and trunks shall be obtained by linear interpolation.
(c) For vessels of Type “B”:
(1) Where the effective length of a bridge is less than 0.2L, the percentages shall be obtained by linear interpolation between lines I and II;
(2) Where the effective length of a forecastle is more than 0.4L, the percentages shall be obtained from line II; and,
(3) Where the effective length of a forecastle is less than 0.07L, the percentages in table 42.20–60(b)(2) of this paragraph shall be reduced by: