SeaBase vs CHRTsail

Less apps. More sailing. Seabase is the offline-first sailing companion. Anchor alarm, offline nautical charts, GPS navigation, tides, and a logbook — every tool you need on the water, all working without a signal. No accounts. No ads. PAY ONCE Seabase is a paid app — a single one-time purchase, and it's yours forever. No subscription, nothing auto-renews, no in-app purchases, no ads. Every offline chart region offered is included with unlimited downloads. You pay once and get the whole app. ANCHOR ALARM Drop a virtual anchor and Seabase watches your position with phase-based drift detection — scope warnings, drift alerts, and critical alarms with sound and vibration. A sliding-window filter rides out GPS noise instead of waking you for it. Arm it after the fact with "Already Anchored" mode, pause and resume on the fly, and control the whole watch from your wrist. Replay any past anchor session on a scrubbable radar track. Built to wake you before your boat does. OFFLINE CHARTS Download nautical chart regions to your phone with OpenSeaMap seamarks built in. A global base layer keeps you covered when you sail past your downloaded zone. NOAA depth overlays for US waters when online. GPS NAVIGATION Long-press the chart to plan a route — built-in land detection flags legs that cross land. Live navigation gives you bearing, distance, ETA, cross-track error, and remaining distance with heading-up auto-rotation. Save routes and replay them. A dedicated GPS Navigator adds a radar HUD plus point-to-point go-to. APPLE WATCH Native watchOS companion — speed, heading, anchor radar, and a navigation arrow on your wrist. Arm, disarm, pause, and resume the anchor alarm from the watch. Start and stop trip recording remotely. Mirrors your iPhone's dark/light theme. TIDES 3,500+ tide stations worldwide, completely offline. NOAA-accurate harmonic prediction from a bundled database — no API call, no signal needed. A clear "now" hero card with a trend chart and high/low times. NEARBY PLACES An offline harbor and anchorage finder covering 25 cruising regions worldwide — marinas, fuel docks, pump-outs, ramps, and more — with a searchable list and an offline map view. Hand off any place straight to the GPS Navigator. LOGBOOK Auto-tracking trip recorder with idle detection, photos, notes, and a speed graph. Shareable trip cards with a route preview. CSV export. Sail Recap turns any recorded trip into a shareable highlight video. REFERENCE Knots with animations · COLREGS rules · NATO phonetic alphabet · Safety-equipment guide (US, EU, AU, UK) · VHF MAYDAY / PAN PAN / SÉCURITÉ guide · IALA buoyage. EMERGENCY Always-dark emergency screen so it works at night. Heave-to guide, quick-reference distress procedures, MOB tracker, and rescue contacts. PRIVACY Your trips, photos, and routes never leave your phone, and your GPS position is never sent anywhere. The only network calls are to map/chart tile hosts for first-time region downloads. No accounts, no analytics, no tracking. LICENSE Recreational use only. Not a substitute for professional navigation equipment, official charts, or sailing certifications. You are responsible for your safety on the water. Built by sailors. Yeoman Ventures LLC, California. www.seabase.app · gosailing@seabase.app

CHRTsail is the product of real frustration with the boating chart-plotter landscape. Charts are either dumbed down, or old and pixelated — and, either way, hard to actually use. We said enough: it's time someone built modern charts and software for the mariner of today and tomorrow. That's what CHRT is all about. CHRTsail is a chart plotter engineered like a precision instrument, built from the ground up on a modern stack. Official chart data, full control over how it renders, and a platform built to work just as well offline as online. BETTER CHARTS Every chart is vector data, rendered fresh on your device — not scanned paper, not a static image — so it's crisp at any zoom, on any screen. Choose your portrayal: the official IHO S-52 ECDIS symbology, or a softer house style built for easy reading in daylight. Choose your detail level too, from a clean overview down to full harbor complexity. CHRTland adds relief, contours, roads and place names on the land side, so the shore reads as a shape, not a blank space. Charts themselves are official Electronic Navigational Charts, sourced directly from the issuing hydrographic office — today, that's NOAA, covering U.S. waters including Alaska, Hawaii, Puerto Rico, the U.S. Virgin Islands, Guam, and American Samoa. More coverage is in development. OFFLINE, BY DESIGN CHRTsail is built offline-first, not offline-as-backup. Download full chart regions before you leave the dock and keep navigating with no signal at all — built for a multi-day passage, not just a harbor stroll. Hazard alerts keep working offline too, clearly labeled as reading only what's downloaded to your device — never silent, and never pretending to see everything the online check would. The barometric-pressure trend needs no network to begin with, and logs itself alongside your track either way. Running low on charge? Emergency Battery Mode stretches it by slowing how often things refresh — never by turning off anything that matters. ONE ACCOUNT, EVERYWHERE The same CHRTsail account carries across iPhone and iPad, CHRTsail for Mac, and CHRTweb in your browser (in beta) — plan a passage at the chart table, then pick it up on the water. Live position and hazard alerts live here, on the device that's actually with you underway. NATIVE, TOP TO BOTTOM Live Activity, Lock Screen, Dynamic Island, and Home Screen widgets — built in, not bolted on. Your position, speed, and next waypoint stay visible while you're underway without unlocking your phone; a Home Screen widget surfaces the tide without opening the app at all. Every setting — chart style, complexity, units, safety depth, night mode — follows you everywhere. WAYPOINTS & ROUTES Drop a waypoint with a tap, plan a multi-leg route across a whole passage, and navigate to any mark with bearing, distance, time to waypoint, and cross-track error. Share a route with your crew — sent directly to people you've connected with, never a public link. WEATHER, TIDES & CURRENTS NOAA harmonic tide and current predictions, computed right on your device — a scrubbable curve, station markers on the chart, and the next high or low wherever you're looking. Observed conditions from the buoys that are actually measuring nearby — wind, waves, pressure — with the station named and the reading's age always in view. Full National Weather Service marine zone forecasts and active warnings, read straight from the source, not trimmed to a headline. AND EVERYTHING ELSE A PASSAGE NEEDS Hazard alerts ranked against your own declared safety depth — arithmetic, not a guess, and never a verdict. A logbook that records itself, passage after passage. Anchor watch, Man Overboard, and a boat profile that knows your draft. CHRTsail provides situational awareness only. It is not SOLAS-compliant, not a certified ECDIS, and not intended for primary navigation — and it is not a substitute for official charts, publications, or prudent seamanship.