DS-THEORY-L2.2

Rule of Twelfths and Secondary Port Basics

DS-THEORY-M2 · Tides and Tidal Streams · DS-THEORY-M2-A Predicting heights of tide at standard and secondary ports and reading tidal stream data.

When there is no curve to hand, **the rule of twelfths** gives a quick estimate; secondary ports borrow their tides from a standard port.

Independent study. xplor is not an accredited training provider and awards no certificate or Certificate of Competency. This course does not replace the RYA Day Skipper Theory course and exam at an RYA Recognised Training Centre, or the practical course afloat. AI-drafted content pending subject-matter-expert review.