Historical clue formulations

• They follow springs by about a week — 2019-09-08
• Occurrences during half-moons — 2017-12-07
• Minimum-range tides — 2014-09-03
• Some tides — 2014-06-19
• Some tides — 2012-02-03
• Occurrences between springs — 2011-08-05
• Some tides — 2010-03-24
• Some tides — 2009-11-29
• Certain tides — 2007-02-18
• Some tides — 2003-10-15
• Certain 111-Downs — 2003-08-17
• Some tides — 2001-12-20
• Some tides — 2000-09-24
• Semimonthly tides — 1998-05-07
• Tidal points — 1997-09-25
• Some tides — 1995-05-28
• Tide types — 1994-10-06