Secondary Ports

Standard ports have full daily high- and low-water predictions. A paper tide publication can provide secondary-port differences from a named standard port: separate time corrections for HW and LW and height corrections or interpolation methods tied to the standard-port heights.

Begin with the correct standard-port values for the date. Apply the secondary port's HW correction to HW and its LW correction to LW. Apply height corrections using the band, columns or interpolation instructed by the publication; do not assume one constant correction fits every tide.

Once the secondary high and low waters are established, use the supplied local curve or method if an intermediate height is required. Some authorised digital products provide direct predictions for the selected secondary location; in that case follow the product's stated method and time basis instead of correcting the value a second time.