Equipment Guide · Interactive Exercise · Passage Planning
No-Go Areas — Plan a Route Around ThemVerified
Set your draft, required UKC (a NOT LESS THAN limit) and height of tide, then plan a route through a fictional channel between two shoals — and watch a route that was safe at high water turn no-go the moment the tide falls.
Educational simulation only. This chart is fictional, not to scale, and must never be used for navigation.
Hover or tap a cell to see its numbers.
NLT — Not Less Than: the water under the keel must never be less than this. In real passage planning this figure is not a single arbitrary number — it is itself derived from squat, heel/list allowance, wave/swell response and a safety margin on top of a base clearance. This exercise takes it as one input so the no-go-area lesson stands on its own; how Required UKC itself is built (UKC & squat) is a topic of its own, for later.
XTE corridor (NMT 0.1 NM) — NMT — Not More Than: your cross-track error should never exceed this.
Tap the chart to add a waypoint. Drag a waypoint to move it. Tap one to select it, then remove it below.
Add at least two waypoints to plan a route.
Step 1 of 4
1 · Set your limits
Enter your Draft and Required UKC — a NOT LESS THAN (NLT) limit: the water under the keel must never be less than this. Height of tide starts at a high-water value. These three numbers are the only inputs the no-go calculation uses.