Question

Which of the following is a reasonable tide time on day 7?

high tide at about 8:20 a.m.


low tide at about 4:55 a.m.


low tide at about 3:05 a.m.


high tide at about 10:30 a.m.

Answer 1

I don’t have the original reference day/time — can you confirm which tide/time you’re using as the starting point? Without that I can’t pick the correct option.

Quick guidance so you can check:

- The same-phase tide on the next day occurs ≈ 50 minutes later (the lunar day ≈ 24 h 50 m). So to get day 7 from day 1 add 6×50 min = 300 min = 5 hours. Example: if day 1 high is 8:20 a.m., day 7 high ≈ 1:20 p.m.
- A high and the next low are ≈ 6 h 12.5 min apart. So from a high at 8:20 a.m. the following low would be ≈ 2:32 p.m., and from a low at 3:05 a.m. the next high would be ≈ 9:17 a.m.

Using the first interpretation (high at 8:20 a.m. on day 1), day 7 high would be ≈ 1:20 p.m., so none of the listed options (8:20 a.m., 4:55 a.m., 3:05 a.m., 10:30 a.m.) is reasonable. If you give the starting tide/time I’ll compute which choice is correct.