A tide table is a predictive tool that provides specific details about the daily rise and fall of ocean waters. It forecasts tidal patterns for a given location, helping users anticipate changes in water levels. These tables provide predictable information about the ocean’s vertical movement, influenced by gravitational forces from the moon and sun.
Core Tidal Information
A tide table presents fundamental data points concerning water levels. Each entry includes the specific date and geographic location. For each day, the table lists the times when the water reaches its highest point (high tide) and its lowest point (low tide). High tide occurs when the water level reaches its maximum elevation. Conversely, low tide signifies the moment the water level descends to its minimum.
Tide tables also provide the predicted height or depth of these high and low water levels. Heights are measured relative to a specific reference point, or datum, such as Mean Lower Low Water (MLLW) in the United States. This datum represents the average of the lowest low tides observed over a 19-year period. The difference in height between a high tide and a subsequent low tide is the tidal range, which varies depending on location and moon phase. For instance, “spring tides,” occurring during new and full moons, exhibit higher high tides and lower low tides due to the sun and moon’s gravitational pull.
Supplemental Environmental Data
Beyond core tidal predictions, tide tables often include additional environmental information. This features sunrise and sunset times for the specified location. These details are relevant for planning marine activities, particularly for safety during dawn and dusk. Knowing when daylight begins and ends aids in navigation and general awareness for those on or near the water.
Moon phase information is also included in these tables. The moon’s phases directly correlate with the strength of tidal forces, influencing whether tides are stronger (spring tides) or weaker (neap tides). Knowing the moon phase offers context for predicted tidal heights and helps users anticipate larger or smaller tidal ranges throughout the lunar cycle.
Understanding Tidal Current Data
While tide tables detail the vertical movement of water, some also provide information about the horizontal movement of water, known as tidal currents. Tides cause water to move laterally, creating these currents, which are distinct from vertical changes in water height. A “flood current” describes water movement towards the shore as the tide rises, while an “ebb current” refers to water flowing away from the shore as the tide falls.
Data points for tidal currents include the times of maximum current strength for both flood and ebb flows. These are periods when the water moves most rapidly. Tables also indicate the times of “slack water,” a brief period when the tidal current is at its minimum or nearly still before reversing direction. Slack water does not always coincide precisely with high or low tide, but occurs when the horizontal flow of water changes.
Practical Applications and Interpretation
Tide table information is applied by various groups for practical purposes. Boaters rely on tide tables for safe navigation, especially when traversing shallow waterways or considering bridge clearance. Knowing predicted water depths helps them avoid running aground or damaging vessels. Anglers use tide data to predict fish feeding patterns, as many species are more active during moving tides.
Beachcombers and coastal residents consult tide tables to plan activities like exploring tidal pools, accessible only at low tide, or for safety when walking along the shoreline. Understanding tidal patterns helps prevent being cut off by a rising tide. Surfers also use tide tables to anticipate optimal wave conditions, as tide levels can impact wave breaks.
Users interpret the tabular format by identifying dates, locations, and correlating times with predicted heights. Heights are presented in feet or meters, indicating the water level relative to a standard datum. Times are given in local time zones, ensuring accurate planning for activities.