Precautions During Use
Display Information Accuracy
Tide Graph Precautions
For Japan area oceans, tide times and level changes are predictively
calculated using harmonic constant data obtained from Bibliography 742
Tidal Harmonic Constants Tables, Japanese Coast (February 1992)
published by the Hydrographic Department of the Japan Coast Guard, and
from the
List of Tidal Stations (2015) published by the Japan Meteorological
Agency. For other area oceans, tide times and level changes are predictively
calculated using harmonic constant data obtained from NOAA, NOAA CO-
OPS, and the NOAA Tides & Currents website, and the U.S. DEPARTMENT
OF COMMERCE / COAST AND GEODETIC SURVEY January 1942 TH-1.
Actual tidal phenomena fluctuate in accordance with weather, the season,
and various other factors, and may give rise to irregularities not in accordance
with calculated values. Certain conditions may result in some deviation from
actual tides. Because of this, the information produced by the Tide Graph
function of this app and watch should be treated as approximate reference
information only. Never use it for navigation or any other decisions about tide
that may put safety at risk.
Sunrise/Sunset Precautions
Sunrise and sunset calculations are performed using the following azimuths:
North: 0
degrees, East: 90 degrees, South: 180 degrees, West: 270 degrees.
Calculation results include error of multiple seconds, and error becomes
greater at higher latitudes. Calculations assume a level horizon, and local
topography is not taken into consideration.
Moon Age Precautions
Moon ages displayed by this watch are based on the calculation described
below.
(1) Elongation is calculated using solar and lunar coordinates produced by
functional calculus.
(2) Moon age is calculated based on the correlation between the elongation
and average moon age.
Though the lunar period averages 29.53 days, it actually fluctuates by as
much as ±1 day, so this calculation produces an error of up to ±1 day.
EN-117
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