Anyone shopping for a boating GPS app in the United States runs into the same shortlist: Helm Boating, Savvy Navvy, Navionics Boating from Garmin, iNavX and i-Boating. They all put a nautical chart on your phone. What separates them is what the app does with that chart once it is on screen — which data it reads, how it treats depth, and how much of it still works when the signal drops.
This page sets out exactly what Helm does, source by source, so you can hold it against whatever else you are considering. Helm Boating is published on the App Store as Helm Boating: GPS, Chart & Map, built by Loop Mobile FZCO in Dubai, United Arab Emirates, and it is free to download.
The column on the right is deliberately left empty: every app handles these differently and the only honest answer for a third-party product is to check its own listing. The middle column is Helm, and every line in it is something the app does today.
| What to compare | Helm Boating | Other apps |
|---|---|---|
| Chart source | Official NOAA electronic navigational charts (ENC), read directly | Varies by app |
| Depth sources | Four, merged: NOAA ENC, USACE eHydro dredging surveys, state lake elevation data, live NOAA CO-OPS tide | Varies by app |
| Age of the measurement | Shown with the depth — you see the date the survey was taken | Varies by app |
| Chart confidence | CATZOC, the chart's own zone-of-confidence rating, surfaced on the map | Varies by app |
| Your boat's draft | Entered once; water you cannot cross is shaded and routes plan around it | Varies by app |
| Inland lakes | Charted from state lake elevation surveys, not left blank | Varies by app |
| Offline coverage | 161 downloadable chart packs; charts, routing, depth, tides and the anchor alarm run from the device | Varies by app |
| Tides and currents | NOAA CO-OPS predictions on the MLLW datum; current arrows rotate as you scrub through the day | Varies by app |
| Weather | Animated wind, wave and current overlays, multi-day strip with three-hour columns | Varies by app |
| Underway display | Depth, speed over ground and course over ground on one strip, anchor alarm, AIS, satellite and night styles | Varies by app |
| Logbook | Every trip recorded and replayable | Varies by app |
| iPad | Native iPad layout | Varies by app |
| CarPlay | Chart view on the vehicle's built-in display | Varies by app |
"Best charts" is really a question about data. Helm reads NOAA electronic navigational charts in the S-57 vector format published by NOAA's Office of Coast Survey. Soundings, contours, buoys, beacons, obstructions and channel limits in the app are the ones NOAA publishes, with NOAA's own scale and quality metadata attached.
Because an ENC is structured data rather than a picture, Helm can do arithmetic with it. A shoal at the mouth of an inlet is an object with a depth value, so the app can compare it to your boat's draft and answer the question directly.
A charted sounding describes the bottom at the moment it was surveyed, at chart datum. Helm adds three further sources so the number on screen describes today:
Two things travel with that merged number. The survey date, so a channel measured last season reads differently from a bar last sounded generations ago. And CATZOC, the confidence field inside the ENC that records what class of survey produced the depth — Helm draws it on the chart, so a fully surveyed channel and an area charted from older reconnaissance work look different from each other.
Savvy Navvy is a well-known passage-planning app among coastal boaters. If you are weighing it against Helm, these are the points where Helm's approach is specific enough to check line by line:
Both apps are on the App Store, and each listing sets out its own chart sources and coverage. That is the comparison worth reading before you pick.
Navionics Boating is Garmin's marine chart app and a familiar name on US boats. Offline behavior is the right axis to compare on, because it is the one that matters at the exact moment you cannot check anything: ten miles out, or on a lake with no bars.
In Helm, coverage is packaged into 161 downloadable chart packs. You take the regions you run and leave the rest. Once a pack is on the device, the following run with no cell service at all:
Routes, markers, tracks and the logbook sync across your own devices when you are back in range, so a spot saved on the phone at the ramp is on the iPad at the helm.
iNavX is a long-established chartplotter app with a following among offshore sailors. Helm is built around one question — what is under the hull, and can this boat cross it — and answers it in full: four merged depth sources, the survey date, CATZOC and draft-aware routing, on official NOAA charts, offline, on iPhone, iPad and CarPlay.
This is the case Helm was built for. Your draft is part of the chart, the water you cannot cross is shaded, and routes are planned around it instead of straight through it.
Lake depth in Helm comes from state elevation surveys rather than NOAA charts, so inland water is charted water with contours you can read, and it works with no signal once the pack is downloaded.
Save spots, read the depth contours around them, and come back to the same place later from your recorded trips, with water temperature in the forecast strip where data exists.
Helm has a native iPad layout and a CarPlay interface, so the same charts and the same saved routes follow you from the car to the console.
Judge it on data, not on the map style. Ask which charts the app reads, whether it adds anything to them, whether it tells you how old a sounding is, whether it knows your boat's draft, and what still works offline. Helm Boating reads official NOAA electronic navigational charts, merges USACE eHydro dredging surveys, state lake elevation data and the live NOAA CO-OPS tide into one depth reading, shows the survey date and the CATZOC confidence rating, plans routes around water too shallow for your draft, and runs from 161 downloadable chart packs with no cell service.
Charts come down to the data underneath them. Helm uses official NOAA ENC vector data directly, then layers USACE eHydro channel surveys, state lake elevation data and the live NOAA tide over it, and shows the date and confidence class behind each depth. Savvy Navvy, Navionics Boating, iNavX and i-Boating each describe their own chart sources on their listings, and that is the comparison worth making.
Both are marine navigation apps with passage planning. Helm's specifics: four merged depth sources with the survey date attached, CATZOC drawn on the chart, draft-aware routing that shows the shallowest point on a leg, state-surveyed lake depth for inland water, 161 offline chart packs, AIS, anchor alarm, logbook, native iPad and CarPlay.
Compare them on what keeps running when the signal is gone. With a Helm chart pack on the device, the NOAA charts, depth against your draft with the survey date, draft-aware routing, the measure tool, tides and currents, the anchor alarm and trip recording all keep working offline. Coverage is split into 161 packs so you download only the water you run.
Yes. Coastal water, the intracoastal, rivers and inland lakes. Lake depth comes from state elevation surveys rather than NOAA charts.
Yes. The iPad layout is native rather than a stretched phone screen, and the chart view appears on a CarPlay vehicle's built-in display.
Loop Mobile FZCO, a software company registered in Dubai, United Arab Emirates. The app is listed on the US App Store as Helm Boating: GPS, Chart & Map and is free to download.
Helm is free to download and opens on a 3-day free trial that asks for no payment up front and sends a reminder before it ends. After that it is $99.99 per year — about $8.33 a month — for one plan that includes everything on this page: all 161 chart packs, the four merged depth sources with survey dates and CATZOC confidence, draft-aware routing, NOAA tides and currents, weather on the chart, AIS, the anchor alarm, the logbook, the native iPad layout and CarPlay.
There is no chart cartridge to buy, no plotter to own and no separate chart library to subscribe to. The NOAA electronic navigational charts Helm runs on are public data. Billing is handled by Apple, so the subscription is cancelled from your own Apple ID settings at any time.
Helm Boating