Keeping your boat shipshape!

Calculators

Quick, grounded boating math — the same formulas as the AftLog app.

Same formulas as the AftLog app. Metric-first with imperial conversions. Inputs are clamped to safe ranges; results are colour-coded.

1. Fuel burn

How much fuel an engine uses at a given throttle.

HorsepowerThrottle fraction (0-1, cruise ~0.7)2-stroke

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How much propeller efficiency you're losing at speed (lower is better).

Speed km/hRPMProp pitch (inches)

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The target trailer tongue weight for safe towing.

Total weight kgPercentage (approx. 10)

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How much rode (line) you need for a given depth and scope.

Water depth mBow height mScope ratio (e.g., 5:1)

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Approx. voltage loss over a cable run (keep under 3 V).

Run length mAmpsCable size mm²

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How much oil to add for a 2-stroke fuel mix.

Ratio (e.g., 50:1)Fuel L

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How far you can go on a tank of fuel, factoring in reserves & conditions.

Tank size LReserve %Burn rate L/hrCruise speed km/hWind loss (%)Wave loss (%)

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How long a battery will last at a given load.

Capacity (Ah)Average load (A)Discharge depth (%)

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