Fig 1.
G-Class vessel post-retrofit, modified from the original blueprint provided by Maersk. Changes from pre- to post-retrofitting are identified with arrows.
Table 1.
Automated identification system data sources.
Fig 2.
Study site in the Santa Barbara Channel.
Top: Pre-retrofit transits are shown in blue. Bottom: Post-retrofit transits are shown in red. The location of the High-frequency Acoustic Recording Package (HARP) is labeled with a square. The inset map in the upper right corner shows the north-south Traffic Separation Scheme as white lines.
Fig 3.
G-Class Maersk vessel draft measurements.
G-Class Maersk vessel draft measurements pre-retrofit (blue circles) and post-retrofit (red squares), provided by vessel Chief Engineers. Pre-retrofit draft measurements were shallower on average than post-retrofit draft measurements.
Fig 4.
Gerda Maersk noise levels pre- and post-retrofit.
Radiated noise level (top) and monopole source level (bottom) from two transits of Gerda Maersk pre-retrofit (blue) and post-retrofit (red). The pre-and post-retrofit speed through water was 6.0 and 6.1 m/s, respectively. The pre- and post-retrofit draft was 11.2 and 12.2 m, respectively.
Fig 5.
G-Class Maersk vessel noise levels in relation to speed through water.
Broadband radiated noise level (left) and monopole source level (right) in relation to Speed Through Water for 111 G-Class Maersk transits pre-retrofit (blue circles) and post-retrofit (red squares) for low-, mid-, high-, and very high-frequency bands.
Fig 6.
Differences in dB pre- and post- retrofit.
Differences in dB between the pre- and post-retrofit radiated noise level (left), and monopole source level (right) for low-, mid-, high-, and very high-frequency bands.
Table 2.
Radiated noise levels and monopole source levels pre- and post-retrofitting.
Fig 7.
Estimated marginal means for noise levels pre- and post-retrofitting.
Estimated marginal means (EMMs) ± standard deviation of radiated noise level (LRN) and monopole source level (LS) pre- and post-retrofitting.
Fig 8.
Difference in estimated marginal means for noise levels pre- and post-retrofitting.
Difference +/- standard error of estimated marginal means pre- and post-retrofitting for radiated noise levels and monopole source levels.
Fig 9.
Investigation into monopole source level interaction with speed through water.
Noise reduction of retrofit (dB) with Speed Through Water for low-frequency (8–40 Hz) monopole source level. Estimated coefficients and 95% confidence intervals are displayed.