Helm Boating: GPS, Chart & Map

Helm is a US marine navigation app for boaters who run shallow, unfamiliar or poorly charted water and want to know what is under the hull before they get there.

YOUR DRAFT IS PART OF THE CHART
Enter your boat's draft once. Helm shades the water you cannot safely cross and plans routes around it, instead of drawing a straight line through a two-foot shoal.

DEPTH FROM FOUR SOURCES, NOT ONE
Most chart apps show you one survey and leave the rest to you. Helm combines NOAA electronic navigational charts, fresh USACE eHydro dredging surveys, state lake elevation data and the live tide, then tells you what is actually under your keel right now, with the date the measurement was taken.
It also surfaces the chart's own confidence rating (CATZOC), so you can see when a sounding is old or low quality rather than trusting every number equally.

TIDES AND CURRENTS
Tide predictions come from NOAA CO-OPS against the MLLW datum. Tidal current arrows rotate with the time you scrub to, so you can see whether you will be pushed or held back before you commit to a pass.

WEATHER YOU CAN READ AT A GLANCE
Animated wind, wave and current overlays on the chart. A multi-day strip with three-hour columns for wind, gusts, air temperature and rain, plus water temperature where data exists. Outside US waters the forecast falls back to a global model so the app still works.

OFFLINE FIRST
Coverage is packaged into 161 downloadable chart packs. Take the ones you need and leave the rest. Once a pack is on the device, charts, routing, depth and the anchor alarm all keep working with no cell service, which is the point on open water and on most lakes.

WHILE YOU ARE UNDERWAY
- Depth, speed over ground and course over ground on one strip
- Anchor alarm that wakes you if you drag
- Nearby vessels on AIS
- Satellite and night chart styles
- Every trip recorded to a logbook you can replay

QUESTIONS PEOPLE ASK

Does it work without cell signal?
Yes. Download the chart packs for your area first and the app keeps working offline, including routing, depth and the anchor alarm.

Is it only for the ocean?
No. Lakes, rivers, intracoastal and coastal water are all covered. Lake depth comes from state elevation surveys rather than NOAA charts, which is why inland water is not a blank space here.

What makes it different from other chart apps?
Most of them render a chart and leavou. Helm knows your dr