Spring & neap cycles
Why the range doubles every two weeks, and what that means for your keel.
Two springs a month
When the sun and moon line up — new moon and full moon — their pulls add together and the range grows. Those are spring tides, and they have nothing to do with the season.
new moon spring tides · biggest range first quarter neap tides · smallest range full moon spring tides · biggest range last quarter neap tides · smallest range
Neaps are the gentle ones
At quarter moons the sun and moon pull at right angles, the range shrinks, and the water just… relaxes. Neap weeks are the easiest weeks to run a bar or a shallow channel.
Why a spring range matters
A marina entrance that's fine at neaps can be a wall of standing water at springs. Always check the range, not just the time, before a tight entrance.