published 1977
Our Yorkshire coast has a profusion of geology but also presents many hazards by reason of its numerous tide-trapped inlets, unscalable cliffs and wave-cut platforms, so that a reasonable knowledge of the tides is essential to intending visitors. Local tide-tables do exist, but are not readily available and in any case need renewing annually. However, many diaries and some calendars show the phases of the moon usually, though not always, the hour of the day at which the phase occurs.
On this coast, low tide falls around noon or in the early afternoon from a day or two after New Moon for most of a week, and similarly after Full Moon. The weeks following First Quarter and Last Quarter are generally unsuitable, high tides then prevailing in the afternoons. The times of high tide throughout the lunar month can quickly calculated from a simple and easily-remembered formula:-
Find the date of the immediate preceeding New Moon (or Full Moon) and the hour at which the phase occurs. Then, for this or a subsequent date, high tide at Bridlington, in GMT, is at 04.15 - 2 minutes/hour + 50 minutes/day
and of course low tide follows at or about 6¼ hours. During the period of British Summer Time, do not forget to add one hour to the result. The formula represents & gross simplification of the complex motion of the moon and is therefore not very accurate but it is good enough to enable visitors to pick the right days and keep out of danger. Its average error is about half-an-hour, but its range of errors is rather more than twice this either way.
Two further points:- if the diary or calendar does not give the hours of the phases, the second term cannot be used. Hence eliminate it and add 25 minutes to the first, giving 04.40 + 50 minutes/day.
Cleverly this will introduce an additional uncertainty of about half-an-hour.
Secondly, for places other than Bridlington additional corrections are needed. For example:
For Whitby subtract 40 minutes;
For Scarborough subtract 15 minutes;
For Withernsea, add 30 minutes.
The tides sets from the north along the whole of the Yorkshire coast and similar extensions of these figures with the aid of a map will suffice for other localities.
copyright Hull Geological Society 2021