FA-69235 / Tide and marine navigation tables / Member archive

Light geographic and visible range: Horizon constant for feet is used with metres · case 05

Every light is sighted too early relative to a metric table.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

Input [he, hl, nominal, mhws, tide]: observer height of eye (m), light elevation charted above MHWS (m), nominal range (nm), MHWS and current tide above datum. Effective light height = hl+(mhws-tide). Geographic range = 2.08*(sqrt(he)+sqrt(effective)). Visible range = min(geographic, nominal); the limit is "geographic" when geographic<nominal else "luminous". Return [geo rounded 1, visible rounded 1, limit].

Why this case matters

Tide tables and passage plans turn published predictions into go/no-go decisions about depth, clearance and timing.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
light geographic and visible range [16, 36, 20.8, 3.0, 3.0]	`[11.7, 11.7, "geographic"]`	`[20.8, 20.8, "luminous"]`	Failed

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