Understanding Moon Calendar

[MikeHoncho]

I have a G-Shock Gulf Master that I have gotten really good with except understanding the Moon Day function. I understand the basic physics of the moon and its effects on the earth and our tides but I would like to better understand and know how to better apply the moon calendar function of the watch to the tide cycles.

Pretty much the watch just tells me "age" of the moon in days. Any help is appreciated. I've been Googling it but just come up with the basics of the moon and tides, not on the days.

 

[Kings Gambit]

I have a G-Shock Gulf Master that I have gotten really good with except understanding the Moon Day function. I understand the basic physics of the moon and its effects on the earth and our tides but I would like to better understand and know how to better apply the moon calendar function of the watch to the tide cycles.

Pretty much the watch just tells me "age" of the moon in days. Any help is appreciated. I've been Googling it but just come up with the basics of the moon and tides, not on the days.

The lowest tidal ranges (i.e., moderate lows, moderate highs) occur, or very nearly so, at the “half moons”, which would be moons of either 7 or 21 days of the moon’s daily age, beginning with new moon. Those tides are neap tides. The greatest tidal ranges (i.e., highest highs and lowest lows) occur, or very nearly so, at the new and full moons. Those tides are spring tides. If the daily age of the moon is, say, 5 days, tides are approaching moderate ranges with moderate tidal flows. If the age is 12 days, tides are approaching the extreme ranges with strong tidal flows. Thus, the extreme ranges would coincide with a full moon of about 14 days age, and then again with the new moon when the daily calendar is reset, etc.

 

[Kings Gambit]

The lowest tidal ranges (i.e., moderate lows, moderate highs) occur, or very nearly so, at the “half moons”, which would be moons of either 7 or 21 days of the moon’s daily age, beginning with new moon. Those tides are neap tides. The greatest tidal ranges (i.e., highest highs and lowest lows) occur, or very nearly so, at the new and full moons. Those tides are spring tides. If the daily age of the moon is, say, 5 days, tides are approaching moderate ranges with moderate tidal flows. If the age is 12 days, tides are approaching the extreme ranges with strong tidal flows. Thus, the extreme ranges would coincide with a full moon of about 14 days age, and then again at the new moon when the daily calendar is reset, etc.

Seafarers, rather than expressing moon age in days, insert more moon phases to keep time. For example, waxing crescent means a moon heading toward a position of half moon, on its way to full moon. Once past the half moon, it becomes a waxing gibbous on its final approach to full moon. Once past the full moon it becomes a waning gibbous on its way to half moon of about 21 days. Once past that half moon it becomes a waning crescent on its way to the new moon, where it starts over. You could also add, waxing thin cresent for a couple of days past new moon, and waning thin cresent for a couple days before the new moon, etc.

In case you suddenly awaken from a Rumpelstilskin-type disorientation of the past few days (not years) you’ll recognize a waning gibbous as it rises fairly early after sunset. Every night thereafter the moon rises later and later, passing through its waning phases, heading for the new moon, etc., where the cycle begins anew.

 

[Stu Jackson]

The tide and current tables that I used for decades in San Francisco, what Kimball Livingston called "The most misunderstood little book ever," had the tides and currents and moon phases all on one page. How clever.

The tide & current tables here in Canada do not. I have found lunar calendars and so now have to GASP!!! look at two pieces of paper to find the same information.

OTOH, the free tide chart my f-i-l gets in the mail every month from a real estate dealer has the tides in curves, plus heights with the moon phases.

It's interesting to watch the confluences. One learns to sail with them, rather than against them.

Some times of the year, like Dec-Jan and June-July have major tidal differences and high highs and low lows. Distance to moon from earth does it, IIRC.

Check the depth of your own slip on a really, really low tide time!

 

[Kings Gambit]

In northern fall, winter—the earth gets a tad bit closer to sun as the sun lies at one focus of the earth’s elliptical orbit.

 

[Stu Jackson]

In northern fall, winter—the earth gets a tad bit closer to sun as the sun lies at one focus of the earth’s elliptical orbit.

And then there are the Martians.

 

[justsomeguy]

Isn't that delightful?