Use this sailing calculation as a planning or educational cross-check for navigation, wind and current, rig loads, stability, anchoring, tides, visibility, performance, or recovery under explicitly stated conditions.

Upright air draft (m)

Highest fixed point of the vessel above the waterline when upright.

Beam (m)

Maximum beam of the hull.

Heel angle (°)

Angle of heel from upright; the masthead swings toward the span as the deck edge rises.

Estimate effective air draft while heeled using a simplified rotation about the lower rail. Actual clearance also depends on hull geometry, trim, waves, and the heel pivot. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Effective air draft (m)

Greatest height of any part of the vessel above the water while heeling.

• Actual conditions change with vessel design and loading, sea state, wind, current, tide datum, weather, chart accuracy, equipment, crew, regulations, and safety margins. Simplified formulas do not replace seamanship, approved stability data, or current navigation information.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Cross-check official charts, tide and weather services, instrument data, vessel manuals, and collision regulations; maintain conservative margins and a safe alternative plan.

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  Compute the vertical margin under a chart-datum bridge clearance by subtracting both height of tide and vessel air draft.