Routes that respect your boat

Most chart apps draw a straight line and leave the consequences to you. Helm plans the passage against your draft, tells you where it gets thin, and shows you when the water will be calmest before you commit to a departure.

Draft-aware planning

Enter your draft once. The router treats water you cannot cross as blocked rather than as a suggestion, so the line it draws is one your boat can take. The summary reports the shallowest point on the route up front — not buried three taps deep.

When to leave

The departure planner scores the next day and shows the calm windows as a simple bar. You see at a glance that the passage is comfortable from late afternoon to mid-morning and rough after that, so you leave on the right tide instead of the convenient one.

Why this route

Helm explains its own plan. Rather than a mystery line, you get the legs, the course changes, and the reason a leg goes the way it does. If the router avoided something, you can see what.

What the explanations actually say

Each reason is a sentence with the measurement in it, written per leg. These are the shapes they take, with example figures:

• “Leg B follows the dredged channel for 2.1 NM of its 3.4 NM (62% of the leg).”
• “Leg C is 4.8 NM, 1.4 NM longer than the straight line, because” — and then the thing that was in the way.
• “Leg C steers around a restricted area. The straight line would cross 0.6 NM of it.”
• “Leg D runs within 100 m of charted hazards for 0.9 NM. The route does not enter them.”
• “Leg A at 09:40: the tide adds 1.2 ft at the nearest station, so expect about 8.4 ft at that spot. That height is from the NOAA tide prediction.”

The point of putting the number in the sentence is that you can disagree with it. A detour you can see costs 1.4 NM is a decision you can overrule; a line that silently bends is one you either trust or ignore.

On a dredged channel, Helm names the source

If a leg runs down a dredged channel, the explanation adds a line of its own accord saying the depths there are the chart’s own figures. A maintained channel shoals between surveys, and a router that stays quiet about which kind of number it used is the one that gets you.

The detour notice has two gates, for a measured reason

A deviation gets a sentence if it is large as a percentage of the leg, or if it adds more than half a nautical mile in absolute terms. Either one triggers it. The second gate exists because of a run measured down a 19.7 NM channel: the route deviated by 1.4 NM, which was only 7.6% of the leg, so a percentage-only rule stayed silent about exactly the thing a skipper would want explained.

Tide is reported, never assumed

The router computes at chart datum, MLLW, and never adds tide to decide whether a leg is passable. Tide heights appear beside the leg as information for the hour you plan to be there, and each one names the station it came from and says the height is from the NOAA tide prediction.

A route that only works because the tide cooperated is a route that traps you when you leave an hour late. Planning at datum means the line Helm drew is one you can take at the worst water of the day, and the tide figure tells you how much easier it will be than that.

Along the way

• Course over ground, speed over ground and distance to the next leg while underway
• Ride along the route before you go, to see what it looks like
• Comfort scoring, so a shorter route is not automatically the better one
• Save, share and reverse routes
• Import existing routes and tracks from GPX

Waypoints and markers

Drop and edit waypoints directly on the chart, save fishing spots and anchorages, set a home port, and annotate the chart with your own drawings. Sign in to the same account on each device and all of it syncs, so a route planned on an iPad is on the phone at the dock.

Common questions

Can I import routes I already have?

Yes, Helm imports GPX, so routes and tracks from another app or a chartplotter come across.

Does routing work offline?

Yes, in the packs that carry routing data, which in the US means every coastal pack and Lakes Michigan, Erie and Ontario. Once the chart pack for the area is downloaded, its routing data comes with it, and planning and navigation work without a signal.

Does it handle lakes and rivers?

Draft-aware routing runs where a pack carries routing data, which in the US means the coastal packs and Lakes Michigan, Erie and Ontario. On the rivers, the state lakes and Lakes Huron and Superior, you lay out a route point by point.