🔍 Key Concepts

• Time zone conversion (ZD +5) between EST and the tide table reference time • Using the tide table for the reference port and then applying secondary port corrections for New Bedford, MA • Finding tide height at an intermediate time by using proportional (time) interpolation between high and low water

💭 Think About

• What is the tide table reference time zone, and do you need to convert 1430 EST (ZD +5) to another time before entering the tables? • For 10 April 1983, which high and low waters bracket the time in question, and what are their times and heights at the reference port and at New Bedford after corrections? • Once you know the bracketing high and low waters, what fraction of the time interval has elapsed by 1430, and how does that fraction apply to the change in height?

✅ Before You Answer

• Confirm you are using the correct day and tidal cycle (don’t mix AM/PM or the wrong date). • Verify you applied secondary port time and height differences to New Bedford, not just the reference port data. • Check your interpolation math: elapsed time / total interval, then apply that ratio to the difference in tide heights before choosing between 1.1, 1.2, 1.4, or 1.7 feet.