Historical clue formulations

• Flat-topped straw hat — 2025-02-01
• Headwear for many a barbershop quartet singer — 2022-01-14
• Summer hat — 2014-07-04
• It typically has a ribbon around its crown — 2012-11-09
• Yachtsman, e.g. — 2011-08-22
• One on board an outboard — 2010-11-26
• Summer headgear — 2009-02-28
• Yachtsman — 2003-11-04
• Straw hat — 2003-02-23
• One punting, e.g. — 2000-01-08