Do I need to install anything?

No. It runs in any modern browser, free, with no account required.

For Educators · Dead Reckoning

Dead Reckoning for a viewshed

Built for educators teaching it to a class. Drop a live demo into a lecture or assign it as a shareable link — no lab installs. Simulate a viewshed live below — adjust the inputs and watch it respond, right in your browser.

Dead ReckoningLive

navigating with drift

Controls

Presets

Heading (°)

Boat speed (kn)

Current direction (°)

Current speed (kn)

Time (hours)

Before GPS, navigators tracked position by dead reckoning: from a known start, add up each leg's heading and speed over time. But wind and current push you off your intended track, so the actual path drifts. The gap between where you meant to go and where you ended up is why sailors and pilots learn to correct for set and drift.

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Data Inspector

Distance made good32.6 nm

Drift12.0 nm

Effective speed8.2 kn

Governing equation

x_{k + 1} = x_{k} + v Δ t cos θ, y_{k + 1} = y_{k} + v Δ t sin θ (v = 10 kn, θ = 45°)

Reading this result: Over 4 h the current carries you 12.0 nm off the intended track; steering a correction angle up-current would cancel most of this set.

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Frequently asked questions

Is this good for educators?: Yes — this version of "Dead Reckoning for a viewshed" is framed for educators teaching it to a class. Drop a live demo into a lecture or assign it as a shareable link — no lab installs.
Do I need to install anything?: No. It runs in any modern browser, free, with no account required.