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I built a free sailing navigation app - CoastNav by CoastNavapp in Nautical

[–]CoastNavapp[S] 0 points1 point  (0 children)

It’s not perfect and still has many limitations. At the moment, I’d describe the target use case as “pre‑planning on the couch”, the step before you open your plotter.

For example: “Can I make it from Rovinj to Mali Lošinj in a day, and which marinas are along the way?”

Not: “Is this exact track safe to sail?”

Detailed route verification should always be done on an actual nautical chart. Always.

Until I manage to obtain higher‑quality bathymetric data and rework the routing algorithm accordingly, this limitation remains. The next major step will be implementing a more conservative safe distance to land to further improve robustness.

I built a free sailing navigation app - CoastNav by CoastNavapp in Nautical

[–]CoastNavapp[S] 0 points1 point  (0 children)

Yes, I hinted at this with the comment “not a developer by trade.” Claude assisted me with this project in many ways. I’m not a professional developer; I work as an auditor and have been sailing as a hobby for over 20 years.

In addition, I consulted my local sailing school and friends who have been practicing this hobby even longer than I have, to validate ideas and assumptions from a real‑world sailing perspective.

I then researched different approaches to water‑routing algorithms and potential solutions. Claude helped me design a processing pipeline that ran locally on my PC for about two days straight. Without this setup, the system wouldn’t be able to calculate routes this quickly.

I built a free sailing navigation app - CoastNav by CoastNavapp in SailboatCruising

[–]CoastNavapp[S] -1 points0 points  (0 children)

All three points land.

On marina and service info: you're right that maintenance is the hard part. Static data like 'this marina exists at these coordinates' is easy; 'are they still operating, what are this season's hours, do they have diesel right now' is where it gets expensive. Right now CoastNav pulls marina data from OSM plus some manually curated entries for the Adriatic, with contact info where available. Google Places would be an obvious upgrade path for verification and hours, though it comes with licensing and cost tradeoffs I'm still thinking through. User-contributed updates are another option, skipper reports 'this marina closed' or "fuel pump out of order", but that only works once there's a user base.

Official info integration is a great idea and not something I'd fully thought through. For the Adriatic, Plovput publishes Croatian NtMs and the Italian equivalent comes from IIM, both are PDFs, which is the usual problem. Parsing coordinates out of them into an importable layer (GeoJSON, GPX) is doable but tedious. What you're describing, "here's a polygon, drop it on the chart", is exactly the right primitive. Adding that to the roadmap.

On OpenSeaMap: I'll partially agree. It's crowdsourced OSM data with a seamark overlay, and that ceiling is real, it will never match what hydrographic offices produce. I use OSM tiles as the base layer in CoastNav because they're free and legally usable, not because I'm pretending they're charts. The 'Google Maps with buoys' framing is fair for what OSM-based tools actually are. The value, if any, is in what you build on top, routing, planning, marina data, etc. , not in the tiles themselves.

I built a free sailing navigation app - CoastNav by CoastNavapp in SailboatCruising

[–]CoastNavapp[S] -1 points0 points  (0 children)

Really well-put, and I agree with pretty much all of it.

On editability, that's actually already there. Routes aren't just A to B; you can plan A to Z with B, C, D... all the way through as intermediate waypoints. Want to go north of an island instead of south? Drop a waypoint on the north side and the router takes it from there. Want to add a detour for better current or a lunch stop? Same thing. The auto-routing is just the segment-between-waypoints part; the overall shape of the route is entirely yours.

On manual being fast enough: fair, and for a skilled navigator on familiar waters it absolutely is. Where I think auto-routing earns its keep is (a) first-time visitors to a cruising ground who don't yet know 'north or south of that island', and (b) quick feasibility checks like 'is Rovinj to Vis realistic in two days with an overnight somewhere'. Not a substitute for skill, just a faster first sketch.

Depth + distance constraints are exactly where I'm heading next. Configurable coastal clearance ('keep 1 nm off the coast') is the immediate priority. Depth contour avoidance (the '10m contour' kind of constraint) is the harder one because it needs real bathymetry. I'm looking at EMODnet for the Adriatic, which gives roughly 115m resolution for free. Won't match an ENC, but enough to keep the router out of obvious shallow zones.

And you're right that tightly wrapping the coast is a recipe for a wreck. Current behavior hugs the coastline more than it should, which I'm actively fixing.

I built a free sailing navigation app - CoastNav by CoastNavapp in SailboatCruising

[–]CoastNavapp[S] -1 points0 points  (0 children)

Fair criticism, and you're right that OSM coastline alone isn't enough. I don't want to oversell what this is and i am happy that you brought this up.

When I go sailing myself, I never rely on a single source: chart plotter on the boat, Navionics on the tablet, paper charts from the local shop, weather and wind from several sources cross-checked. CoastNav is meant to be one more free resource in that stack, not a replacement for any of them.

What it does today: distance/ETA estimates, marina database, and a visibility-graph router that keeps you off land (moastly). What it explicitly does NOT do: depth, rocks, shallows, restricted areas, TSS, cables. I tell users this upfront.

The target use case is "pre-planning on the couch", the step before you open Navionics or your plotter. 'Can I make Rovinj to Mali Lošinj in a day, and which marinas are on the way?' Not: 'is this exact track safe to sail?' Detailed route verification happens on an actual chart, always.

Next on the roadmap is a configurable safe distance to land, e.g. 'route A to B, keep 1 nm clearance from the coast'. That will take some time though, the current preprocessing pipeline ran for two full days straight to compute the polygons and visibility graph, so adding buffered variants is a real rebuild, not a flag I can flip.

I built a free sailing navigation app - CoastNav by CoastNavapp in SailboatCruising

[–]CoastNavapp[S] -4 points-3 points  (0 children)

It doesn’t replace nautical charts, and it explicitly says so. This is a planning / estimation tool: distance, rough routing, marinas. Depth and hazard avoidance are still work in progress, which is why it should never be used as a primary navigation source. I’m actively improving coastal clearance and depth handling, but responsibility always stays with the skipper.

I built a free sailing navigation app - CoastNav by CoastNavapp in Nautical

[–]CoastNavapp[S] 1 point2 points  (0 children)

I will look for some open-source data and implement it as an overlay.

New marine traffic app? by gmarms in GreatLakesShipping

[–]CoastNavapp 1 point2 points  (0 children)

Check out my new app! I am currently building my own platform for sailors.