Consequently, the tidal variations caused by once-monthly so-called perigean tides are much more prominent.
While in most waters, the largest tides occur in the same part of the year, in the Bay of Fundy they are more influenced by the shifting coincidence of spring and perigean tides with the result that each year they occur about 47 days later than in the previous year.
Stated otherwise, the perigean tides become more important than the spring tides.
This can be explained by the dominance of perigean tides on the west side of the ocean.
Tidal streams might help to erode the bases of grounded icebergs, and the high waters during perigean spring tides could play a role in refloating grounded and even apparently "stranded" icebergs, especially those stranded at the time of a normal high water.
As a modification of Wood's original idea linking astronomy and the Titanic, we suggest that perigean spring tides during each of those three months--especially the period near the extreme lunar perigee on January 4th--could have helped to refloat icebergs.
Perigean spring tides are outstanding, while apogean spring tides hardly differ from average tides.
This is the case in regions like the Bay of Fundy where diurnal inequality of the tides is of such minor importance that it can be virtually ignored among variations caused by the coincidence of perigean and spring tides.
Heaviest ice conditions occur one or two months before perigean and spring tides combine to form the largest tide of the cycle.
If the time of lunar perigee falls near a syzygy, then perigean spring tides of unusually large range can occur.
It is worth emphasizing that perigean spring tides have greatly increased range, bringing both extremely high tides and extremely low tides on the same day.
During this period of perigean spring tides, all the low waters were lower than normal.