I have just finished reading Cater's explanation for high tides, and that tides will be highest during a New Moon. As an astrologer this makes perfect sense to me. The Sun & Moon, when the (moon is at quarter--90 degree), is when the tension between the two is at it's highest, it peaks a minute after an opposition 180, but their energies merge at 0 degrees. I am guessing Cater is saying that when the Sun and Moon are working against each other so to speak, tides will be at their lowest due to less gravitational pull, because the interaction during the times of squares and oppositions is focussed more between the Sun and the Moon, and not the Earth?
At a New Moon (conjunction to astrologer's) the Sun and Moon are in unison so to speak, and are combing their gravity, which increases the gravitational pull, hence high tides. To an astrologer this makes sense. When reading a chart where one has Sun & Moon Conjunct, or where one was born under a New Moon, indicates an intense merging and interaction of both the Sun's and Moon's energies within the person. Also, people born under a New Moon often have a tendency to hold the power of magnetic healing.
Conjunctions (involving any planets) characterize particularly strong modes of energy flow--conjunction is action. Therefore, I would expect the most "action" or "gravitational pull" on the tides at a New Moon.
If I have interpreted this wrong feel free to correct me.
Leslee