How do I determine the time for high or low tide at locations along the coast?
A tide chart will provide a tidal elevation and time (e.g., high tide of +8.7 ft at 10:35 a.m.) for a known tidal station, such as at the Portland tide gauge. The chart will also provide tidal corrections for different locations along the coastline (e.g., Presumpscot River Bridge, high water height *1.01 and time +0:01). This information tells you that to calculate the time and elevation for high tide at the Presumpscot River, you must multiply the provided high tide for Portland by the correction, and add time to the given tide, since a plus sign is given. Thus, the high tide at the Presumpscot River Bridge would be +8.79 ft (+8.7 ft * 1.01) at 10:36 a.m. (10:35 + 0:01).
