Accuracy of dates relating to moon phases and dates of full moon on Poltips
Moon phases on a tide table only show the day on which that phase occurs, not the precise time. Mathematically there will be a precise time to a fraction of a second that a full moon occurs however, in reality due to various algorithms that can be used to compute the phase of the moon, and the fact that the moon and sun are not point sources of light but in fact 'disks' of light, the time at which the moon is fully illuminated is actually not a single instance in time but can cover a number of minutes.
The algorithm we use to calculate the moon's phase is known to be one of the most accurate so we have complete faith on the mathematically precise moment a full moon (or any other moon phase change) occurs on Poltips. On the occasions where this is close to midnight, for example 23:59pm, a different algorithm used elsewhere might show it occurring on the following day.
For more information on Poltips 4 see our user guide.