Weems and Plath Endurance 125 Clock - Manual (Page 18)

4) It should be noted that other variables such as wind, atmospheric
pressure, the relative position of the moon, and the elliptical pattern of
the sun will affect the tide slightly. These phenomenon least affect the
tide at the time of the full moon. For this reason, the time of the full
moon and to a lesser extent, the new moon are generally the best
times to set your tide clock. Even though you may experience some
slight variations during the days to come, you will find that they will
“average out” and by the time of the next full moon, your tide clock will
accurately depict the correct time of flood and ebb stages. CAUTION:
FOR THE ABOVE REASONS, IF THE EXACT TIME OF TIDE STAGES IS
ESSENTIAL FOR NAVIGATION, ETC., WE SUGGEST YOU CONSULT A
TIDE TABLE.
5) If clock stops, it is most likely due to a dead battery. Remove dead
batteries immediately as they will leak acid causing damage to the
movement and void warranty.*
6) If clock is left unattended for long periods, the battery should be
removed, otherwise, it could become dead and leak acid causing
movement damage and void warranty.*