Moon phases and tidal currents

[ymy]

Could someone explain (or point me to somewhere) the relationship between moonphases, tidal currents and diving. A DM I talked to told me that the best time to dive (in terms of tidal currents etc) was a week to 10 days after the new or full moon. I am not sure I understand the reason for this. I would have thought the period between new and full moons would be when there would be greatest water movement and thus the most currents

 

[Uncle Pug]

Simplified version leaving out a bunch of stuff:

Spring tides are when the moon is new or full and tides are at their extreme...

Neap tides are when the moon is half and tides are moderated...

Think of a disk representing the earth... the tides are high on opposite sides of the disk inline with the gravitational pull and low at the same time on the sides perpendicular to the gravitational pull.

When the moon is full or new it is in line with the sun and its pull and the sun's pull are additive... and the tides heap up higher.

However when the moon is at a right angle to the sun the pull of one works against the other pulling at the low tide sides as well...

 

[ymy]

Uncle Pug, Thxs. But why would currents be especially strong around full/new moon and weaker a week after.

 

[ymy]

Uncle Pug, Never mind. I think I get it now.

 

[Seb]

You know I never thought about it but it makes perfect sense when you 'splain it Pug