Tides and Currents

Course Link: Tides and Currents

Course Description: This course provides mariners with a deep understanding of tides and currents, their underlying causes, behavior, and the methods used for prediction and practical application in navigation.

Course Objectives: Upon completion of this course, students will be able to:

• Explain the fundamental principles of tides and currents.
• Identify and classify different types of tides and currents.
• Predict tidal heights and current speeds using various methods and tools.
• Apply tidal and current information to passage planning, navigation, and safety.

Course Outline:

Module 1: The Fundamentals of Tides

• What are Tides?
  • Defining tides, distinguishing between high and low water
  • Understanding basic terminology (range, amplitude, stand)
• The Gravitational Influence
  • Role of the Moon and Sun in generating tides
  • Concept of gravitational forces and their impact on Earth's oceans
  • Explanation of the equilibrium theory of tides
• Tidal Patterns
  • Classification of tidal patterns:
    • Semi-diurnal (two high and two low tides of approximately equal height per day)
    • Diurnal (one high and one low tide per day)
    • Mixed tides (combination of semi-diurnal and diurnal characteristics)
• Tidal Datums
  • Defining and explaining the importance of various tidal datums (MSL, MHW, MLW, LAT, HAT)
  • Use of tidal datums in nautical charts and depth calculations

• Slack and Ebb Tides

Module 2: Factors Affecting Tides

• Lunar Cycles
  • Influence of the Moon's phases on tidal heights and ranges (spring and neap tides)
• Solar Influence
  • Understanding the Sun's contribution to tides and its interaction with lunar tides
• Geographical Factors
  • How local geography (coastline shape, basin size, water depth) modifies tidal characteristics
  • Concepts of amphidromic points and co-tidal lines
• Other Influences
  • Weather patterns (wind, atmospheric pressure)
  • Seasonal variations

Module 3: Tidal Prediction and Forecasting

• Tidal Tables and Charts
  • Using tidal tables published by NOAA and other hydrographic offices
  • Understanding information presented in tidal tables (times and heights of high and low waters)
  • Interpreting tidal charts and their use in navigation
• Tidal Current Predictions
  • Relationship between tides and currents
  • Using tidal current tables and charts to predict current speed and direction
  • Importance of tidal current information in navigation (narrow channels, harbors)
• Electronic Navigation Systems
  • How ECDIS and other navigation software utilize tidal data for real-time predictions
• Practical Calculation Methods
  • Manual methods for calculating tidal heights at any given time (e.g., rule of twelfths)
• Limitations of Predictions
  • Recognizing limitations and potential impact of unpredictable factors (weather)

Module 4: The Fundamentals of Currents

• What are Currents?
  • Defining currents, distinguishing between various types of currents (tidal, wind-driven, etc.)
  • Understanding basic terminology (set, drift, slack water)
• Causes of Currents
  • Exploring the forces that generate currents, including tidal forces, wind, and density differences
• Current Patterns
  • Identifying and classifying different current patterns, such as rotary currents and reversing currents
• Current Measurement and Observation
  • Traditional methods of current measurement (e.g., current meters)
  • Modern techniques for observing currents (e.g., HF radar, satellite imagery)

Module 5: Factors Affecting Currents

• Tidal Influence
  • Examining the relationship between tides and tidal currents
• Wind Patterns
  • Understanding how wind affects surface currents
• Geographical Factors
  • Exploring how local geography (channel shape, coastline configuration) influences currents
• Other Influences
  • Coriolis effect
  • Density differences (temperature, salinity)

Module 6: Current Prediction and Forecasting

• Current Tables and Charts
  • Using current tables published by NOAA and other hydrographic offices
  • Understanding information presented in current tables (times and speeds of currents)
  • Interpreting current charts and their use in navigation
• Practical Calculation Methods
  • Estimating current speed and direction using simplified methods
• Limitations of Predictions
  • Recognizing limitations and potential impact of unpredictable factors

Module 7: Practical Applications for Mariners

• Passage Planning
  • Integrating tidal and current information into passage planning
  • Considering tidal heights and currents for safe navigation (shallow waters, narrow channels)
• Anchoring
  • Understanding the impact of tides and currents on anchoring
  • Considerations for tidal range, currents, and potential for dragging
• Harbor Entry and Departure
  • Utilizing tidal and current information to determine optimal times for entering and leaving harbors
• Working with Tidal Currents
  • Effects of tidal currents on vessel handling and maneuverability
  • Techniques for navigating in strong tidal currents
• Safety Considerations
  • Emphasizing the importance of accurate tidal and current information for safe navigation

Assessment:

• Quizzes throughout the course to assess understanding of key concepts.
• Practical exercises involving the use of tidal and current tables, charts, and electronic navigation systems.
• A final exam covering all modules.