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.

Opponent rating (s/mile)

Opponent rating in seconds per mile; positive means you owe this many seconds per mile.

Your rating (s/mile)

Your rating in seconds per mile.

Compute the signed per-mile handicap allowance as your rating in seconds per mile minus the opponent rating in seconds per mile. 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]

Allowance per mile (s/mile)

Signed seconds per mile you give or receive; negative means you are owed time.

• 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.

• Current Shear Gain

  Compute the signed current shear across the boundary between the near surface layer and the deeper layer as the near surface speed minus the deeper layer speed.

• Maneuver Time Loss

  Compute the total time and distance lost to a series of maneuvers from the maneuver count, seconds lost per maneuver, and boat speed.

• PHRF Time on Distance Calculator

  Compute a PHRF time-on-distance corrected time by subtracting the rating allowance over the course length from elapsed time.