Planning a passage — depth, sea state, and the smoothest window

Passage planning answers two questions before you get under way: is this route safe, and when should I leave?

Depth charts:
The Map tab has a "Depth" toggle that overlays GEBCO bathymetry. Turtini computes under-keel clearance for you — charted depth minus your vessel's draft minus squat — so shallow water along a route is obvious at a glance.

Planning a passage:
On the Routing tab, open a route and click "Plan passage". Turtini samples the route at roughly fourteen points and, for each leg, pulls:
• Time-phased sea state — wave height, period, and direction at the hour you'd actually be there (Open-Meteo Marine)
• Charted depth and under-keel clearance (GEBCO)
• A seakeeping comfort score — how the motion would feel on that heading in that sea

Finding the window:
The planner then scans a range of departure offsets and ranks them, so you can see that leaving three hours later trades a slightly longer passage for a far smoother ride. Pick the departure that fits your schedule and comfort floor.

This is decision support, not a clearance — the master always confirms the plan against official charts and notices to mariners.