Erie and Ontario are working water. Freighter channels and dredged harbor entrances cut through both of them, and the ground in between is hard rather than soft. Depth changes abruptly here. The useful question on a passage is less how deep the lake is than where the edge of the deep part sits and what is lying on the bottom beside it.
Helm builds the Lake Erie and Lake Ontario pack out of 246 official NOAA ENC cells. That is the fourth highest cell count of the 18 US regions the app divides the country into. Inside those cells are 89,773 individual soundings, 11,467 charted depth areas and 11,910 depth contours, along with 5,741 charted obstructions and 2,665 underwater rocks. The download is 33 MB, and everything in it works with no signal once it is on the phone.
A cell count is a rough measure of how many times the same water has been charted and at how many scales. Erie and Ontario sit at 246, behind only three of the 18 regions, which is what happens where approach and harbor charts stack on top of the general ones. The practical effect is that when you zoom in on an entrance here, there is usually a larger scale cell waiting under you instead of the same coarse picture drawn bigger.
The full count in the pack:
| In the chart pack | Count |
|---|---|
| NOAA ENC cells | 246 |
| Charted soundings | 89,773 |
| Depth areas | 11,467 |
| Depth contours | 11,910 |
| Lateral buoys | 1,617 |
| Lateral beacons | 910 |
| Charted lights | 2,422 |
| Anchorage areas | 17 |
| Bridges | 1,702 |
| Overhead cables | 1,031 |
| Dredged areas | 723 |
| Charted wrecks | 427 |
| Charted obstructions | 5,741 |
| Underwater rocks | 2,665 |
| Restricted areas | 469 |
Counted from the Helm chart pack for Lake Erie & Ontario, built from official NOAA electronic navigational charts. The pack downloads at about 33 MB.
Only one of the 18 regions carries more charted overhead cable than Erie and Ontario, and only two carry more bridges. On most water a skipper thinks about clearance a few times a season. On this one it belongs in the plan on any run that starts inside a river or a harbor, and it belongs there before you cast off rather than at the span.
A cable gets strung where the water is narrow enough to cross, so the stretches carrying the most of them tend to be the ones where turning around is least convenient. A mast or an antenna that clears a span by a foot is a poor thing to find out about under way. How Helm reads charted vertical clearance against the air draft you enter, and what it does when the chart carries no clearance figure at all, is covered on the depth page.
There are 427 charted wrecks in the pack, fifteenth of the 18 regions. Charted obstructions run to 5,741, sixth highest. That ratio is the thing to carry with you: for every charted wreck on these lakes there are roughly thirteen charted obstructions, and an obstruction is the chart recording that something is there without saying what it is.
An unnamed object cannot be reasoned about the way a known hull can. There is no orientation to it, no length, and no telling whether it has settled or collapsed since somebody logged it. What you have is a position and a depth, so the sensible handling is distance.
Underwater rocks are the other half of it, 2,665 of them, eighth of the 18 regions. Rock is why depth on this water goes from comfortable to tight inside a boat length, and why the shallowest point along a line you are about to cut matters more than the average depth of that line.
Across the two lakes the pack holds 723 dredged areas. Taking the charted depth on each, the median is 4.6 m, about 15 ft, and the deepest carries 9.1 m, close to 30 ft. The spread is narrow for a region this size. Most of the maintained water here sits within a few feet of the same figure, and the deeper channels that take commercial traffic are the exception rather than the general case.
Some of those 723 carry 0.0 in the chart's depth field. That is the absence of a published figure rather than a channel with no water in it, and the two are worth telling apart before you plan a leg through one.
Restricted areas come to 469. On water where the channel is also the freight route, they are part of the plan rather than scenery, and a line drawn without looking at them is a line that crosses them.
The pack carries 1,617 lateral buoys and 910 lateral beacons, with 2,422 charted lights across the two lakes. The lights sit seventh of the 18 regions, which is a good part of why a harbor entrance here stays readable after dark. Many of the lateral marks on these lakes are lifted before the ice and reset in spring, so a buoy printed on the chart is not a year round object.
The number that says the most about this water is 4. There are four safe-water marks in the entire pack, the fewest of any of the 18 regions. Safe-water marks belong to landfall, to the long approach where a vessel comes in off open sea and picks up a fairway before anything else. That is not the shape of arrival on Erie or Ontario. You run open lake until the harbor is close, and then you are inside a lateral system almost at once, with very little charted water in between to ease you into it.
Charted anchorage areas total 17, sixteenth of the 18 regions. The chart is not going to hand you many designated places to stop on these lakes, so shelter gets picked off the charted depth and the wind you expect overnight rather than off an anchorage symbol.
These counts describe what the chart pack carries, not the state of the water today. Charted data ages, channels shoal and marks move. Keep a lookout and verify locally.
The pack carries 427 charted wrecks, which puts Erie and Ontario fifteenth among the 18 US regions for wreck count. The larger number is obstructions at 5,741, sixth highest of the 18, plus 2,665 underwater rocks. So the object you are usually keeping clear of on these lakes is an unidentified one rather than a known hull, and the chart gives you its position and its depth without telling you what it is.
More than on most US water. The pack holds 1,031 charted overhead cables and 1,702 bridges, second and third highest of the 18 regions. Any run that begins in a river or inside a harbor is worth checking for clearance before you leave, and Helm reads the charted vertical clearance against the air draft you enter once.
Across the 723 dredged areas in the pack, the median charted depth is 4.6 m, about 15 ft, and the deepest carries 9.1 m, close to 30 ft. Some areas carry 0.0 in the chart's depth field, which means no depth was published for that area rather than that it has no water.
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