Table 2. Ship population statistics and mean broadband sound pressure levels (20–40,000 Hz).
Though abbreviated in the table as dB, the units of the received signal levels (RLS) are dB re 1 µPa and source levels have units of dB re 1 µPa @ 1 m. Variability is reported as a standard deviation of the mean, and speed over ground (SOG) is provided in m/s and knots.
| Ship class | Isolated transits | % of total | Unique ships | RLS dB | SL dB | SOG m/s | SOG knots |
|---|---|---|---|---|---|---|---|
| All classes combined | 2,809 | 1,582 | 110 ± 7 | 173 ± 7 | 7.3 ± 2.0 | 14.1 ± 3.9 | |
| Bulk carrier | 965 | 34.3 | 734 | 111 ± 6 | 173 ± 5 | 7.0 ± 0.8 | 13.7 ± 1.5 |
| Container | 529 | 18.8 | 207 | 116 ± 4 | 178 ± 4 | 9.9 ± 1.0 | 19.2 ± 1.9 |
| Tug | 337 | 12.0 | 85 | 108 ± 5 | 170 ± 5 | 4.2 ± 1.2 | 8.2 ± 2.3 |
| Cargo | 307 | 10.9 | 206 | 113 ± 5 | 175 ± 5 | 7.4 ± 1.2 | 14.4 ± 2.3 |
| Vehicle carrier | 187 | 6.6 | 111 | 113 ± 3 | 176 ± 3 | 8.7 ± 1.0 | 16.9 ± 1.8 |
| Tanker | 148 | 5.3 | 101 | 111 ± 5 | 174 ± 4 | 7.1 ± 0.7 | 13.8 ± 1.4 |
| Military | 113 | 4.0 | 19 | 99 ± 10 | 161 ± 10 | 5.7 ± 1.6 | 11.1 ± 3.1 |
| Fishing | 65 | 2.3 | 28 | 102 ± 9 | 164 ± 9 | 4.7 ± 1.1 | 9.1 ± 2.2 |
| Passenger | 49 | 1.7 | 31 | 104 ± 8 | 166 ± 8 | 7.4 ± 2.3 | 14.4 ± 4.5 |
| Miscellaneous | 41 | 1.4 | 21 | 101 ± 9 | 163 ± 9 | 5.8 ± 3.0 | 11.2 ± 5.8 |
| Pleasure craft | 41 | 1.5 | 35 | 97 ± 10 | 159 ± 9 | 6.4 ± 2.5 | 12.4 ± 4.9 |
| Research | 14 | 0.5 | 4 | 104 ± 6 | 167 ± 5 | 5.7 ± 0.9 | 11.1 ± 1.8 |