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Calcimator

Open Water Sighting Calculator

Calculate how often to sight during open water swimming based on current drift, swim speed, and course width tolerance.

Inputs

knots
m/s
ft

Results

Sight Every N Strokes

68 strokes

Sighting Interval68 sec
Lateral Drift per Minute15.4 m
Extra Distance from Drift2.7%
Distance per Stroke1.1 m
How to Use This Calculator
  1. Enter your Current Speed (water current) and Swim Speed in meters per minute.
  2. Set the Course Width Tolerance in meters (how far off-line you can drift).
  3. Enter how often you sight in strokes (Sight Every N Strokes).
  4. Review Sighting Interval, Lateral Drift per Minute, and Extra Distance from Drift.
  5. Adjust sighting frequency to minimize drift while reducing speed loss from lifting your head.

How the result changes with Current Speed

Current SpeedSight Every N Strokes
0.568 strokes
1.7519 strokes
3.2510 strokes
4.58 strokes

What each input means

Current Speed
Speed of the lateral water current in knots. Check marine forecasts or local conditions for this value.
Swim Speed
Your average swim speed in meters per second. 1.0-1.2 m/s is typical for recreational open water swimmers.
Course Width Tolerance
Maximum acceptable lateral deviation from your intended line before correction is needed.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Current Speed = 0.5, Swim Speed = 1.1, Course Width Tolerance = 50 = 3 input(s) provided
  2. Calculate Sight Every N Strokes
    Sight Every N Strokes = max(sightingStrokes
    68 = 68
  3. Calculate Sighting Interval
    68 = 68
  4. Calculate Lateral Drift per Minute
    Lateral Drift per Minute
    15.4 = 15.4

Engine last updated . Checked against 1 independently-derived test — how we verify calculators.

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