Lesson 1 - Why Weather Matters at Sea

Key Takeaways:

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Marine vs. Land Weather:

• Marine weather changes faster and impacts your route, comfort, and safety more than land-based weather.

• Land forecasts often don’t reflect open sea conditions—especially regarding wind and swell.

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4 Core Weather Elements:

• Air Pressure: High pressure usually brings stable, calm weather; low pressure means change and possible storms.

• Temperature: Drives pressure differences and local winds.

• Wind: Moves from high to low pressure and is influenced by geography.

• Humidity: Leads to cloud formation and rain; adds instability.

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Beaufort Scale Summary:

• Converts wind speed into practical effects on sea state and sailing.

Force 2–4 = ideal for cruising.

Force 5–7 = reefing needed and heavier sea state.

Force 8+ = preparation essential; risk increases.

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Why It Matters:

• Influences sail choice, passage timing, crew safety, and anchoring.

• Helps you anticipate instead of react.

• Being weather-aware is part of being a responsible skipper.