Chart Navigation & Plotting · Tidal Currents — Rotary
In open coastal waters and wide bays, away from confined channels, tidal currents tend to be:
- AConstant in set and drift throughout the tidal cycle
- BStrictly reversing, with two distinct slack-water periods
- CAbsent entirely beyond the surf zone
- DRotary — continually changing direction through the compass, with no true slack, only times of minimum speed✓ Correct
Explanation
In the open sea and broad bays, tidal currents are typically rotary: the direction rotates continuously (clockwise in the Northern Hemisphere) through 360° during a tidal cycle, with no true slack — only times of minimum and maximum speed. Distinct reversing currents with slack water are characteristic of confined channels and rivers.
Authority: Bowditch (Pub. No. 9); NOAA Tidal Current Tables
Practice the full Chart Navigation & Plotting bank
Free spaced-repetition quizzing across 2190 USCG exam questions — it schedules your reviews so the ones you miss come back until they stick.
Related Chart Navigation & Plotting questions
- Chart Basics
On a Mercator chart, one nautical mile is measured using the:
- Chart Basics
The principal advantage of the Mercator projection for navigation is that:
- Chart Basics
Charted depths (soundings) on a U.S. chart are referenced to which tidal datum?
- Chart Basics
Vertical clearances of bridges and overhead cables on a U.S. chart are normally referenced to:
- Distance, Speed & Time
A vessel makes good 12 knots. How far does it travel in 20 minutes?
- Distance, Speed & Time
A vessel covers 9 nautical miles in 45 minutes. What is its speed?