Table 1 Descriptions of predictor variables used in statistical models
Predictor Variable | Abbreviation | Description |
|---|---|---|
Ship Design | ||
Length | LOA | total length of ship in meters |
Gross tonnage | GT | unit less index related to ships overall internal volume |
Horsepower | HP | measurement of engine power |
Service speed | SSPD | speed the ship was designed to travel at for maximum efficiency |
Draft | DFT | average vertical distance between the waterline and the bottom of the hull |
Identification | ID | Maritime Mobile Service Identity (MMSI), a series of 9 digits to uniquely identify ships |
year built | YB | year the ship was constructed |
Operational | ||
Speed | SPD | actual ship speed over ground |
Range | RAN | distance of the ship to the HARP at closest point of approach |
Proportion of speed | PSPD | proportion of the service speed the ships is travelling (SPD/SSPD) |
Other ship | OTH | time to the next ship passage (>1 hour) |
Tones | TONE | presence of spectral tones |
Oceanographic | ||
Month | MTH | month of the year |
Wave height | WVHT | significant wave height (meters) is calculated as the average of the highest one-third of all of the wave heights during the 20-minute sampling period |
Wave direction | MWD | mean wave direction corresponding to energy of the dominant period (DPD). The units are degrees from true North |
Current direction | CDIR | direction the ocean current is flowing toward. 0–360 degrees, 360 is due north, 0 means no measurable current |
Wave period | DPD | dominant wave period (seconds) is the period with the maximum wave energy |
Wind direction | WDIR | wind direction measurements in degrees clockwise from true North |
Wind speed | WSPD | wind speed values in m/s |
