The Allegheny ends where it meets the Monongahela and the two of them become the Ohio, and the reach above that junction is held between dams. That changes the first question a skipper asks. Going upriver the useful question is usually not how much water is under the keel. It is how much room there is over the wheelhouse, and whether the chamber ahead is going to take you or hold you behind a tow that arrived first. The channel is worked water. A loaded string of barges needs most of the width to do its job and has fewer choices about where it goes than you do. A plan drawn as a line between two points knows none of that.
Helm's Allegheny pack covers the reach as one download and carries 288 charted depth areas and 296 depth contours, 118 bridges, 41 overhead cables and 209 charted lights. It holds 21 charted lock features, 14 restricted areas, 12 charted wrecks and a single charted lateral buoy. The whole pack comes down at 1 MB, which is small enough that there is no argument for leaving it off the phone before a trip upriver.
Helm builds chart packs for fifteen US rivers, and on most of the counts the Allegheny lands in the middle of them. Seventh in charted depth areas. Eighth in depth contours. Ninth in bridges. Those ranks describe a reach that has been measured closely over a short distance, which is what tends to happen to water that carries cargo for a living.
The figure worth stopping on is the last one in the list. One charted lateral buoy in the whole pack, on a river carrying 209 charted lights. Three of the fifteen rivers have any lateral buoys at all, and the Allegheny is second of those three with its one. Anyone arriving here off a bay notices the difference straight away. There is no line of cans to pick up and follow. The chart gives you the bank and the fixed marks standing on it, and holding your water means reading those.
| In the chart pack | Count |
|---|---|
| Bridges | 118 |
| Overhead cables | 41 |
| Charted lights | 209 |
| Lock features | 21 |
| Charted depth areas | 288 |
| Depth contours | 296 |
| Charted wrecks | 12 |
| Restricted areas | 14 |
| Lateral buoys | 1 |
Counted from the Helm chart pack for the Allegheny River, built from the official inland electronic navigational charts published for it. The pack downloads at about 1 MB. Lock features are counted as the chart draws them, with chambers, gates and dams as separate objects.
Add the two together and the pack carries 159 charted crossings over water that downloads at 1 MB. The bridges are the bulk of it at 118, ninth of the fifteen rivers. The cables come to 41, eleventh. Neither count is the biggest on the list. Both of them are over your head on the same afternoon.
A bridge is charted with a vertical clearance you can look up beforehand. A cable is charted the same way, and with a cable that is the end of the conversation, because there is nothing to call on the radio and nothing to open. Forty one of those on one river is enough that a mast turns the trip into a planning exercise before it becomes a navigation one.
Set your air draft in Helm once and the charted clearance on each of the 159 gets checked against that figure. For a flybridge running with the antennas up, the working number is rarely the one on the spec sheet, so it is worth measuring rather than remembering. For a rig, the crossings decide how far up this river the trip goes, and they decide it at the dock rather than at the bridge.
The pack carries 21 charted lock features, eighth of the thirteen rivers Helm charts that have any. Read the number carefully. It counts chambers, gates and dams as separate items, so it is not a count of lock sites and it should not be used as one. C.W. Bill Young is among the names the chart data carries for this river.
What locking does to a day is change the unit you plan in. Distance divided by speed produces a number with very little connection to when you actually arrive. The chamber ahead is either ready or it is not. A tow already sitting in the approach goes through first, and if that tow has to be broken up and put through in pieces it holds the chamber for a long stretch of your morning.
Helm will draw the line and report the distance between the points you picked, which is the part a chart can answer honestly. The clock on a river day belongs to the chambers. The habit that survives contact with this water is treating each one as a stop of unknown length rather than a point you pass through.
209 charted lights, tenth of the fifteen, against that single charted lateral buoy. The count is not a mistake. On this water you are working from fixed marks and from the shape of the bank, not from floating aids that shift with the season and the ice.
The pack also carries 14 restricted areas, ninth of the fourteen rivers with any. A restricted area costs more on a river than the same area costs on open water. Out on a bay you go around it and lose a few minutes. Here the room you give it comes out of the same width a loaded tow needs to work in. Meeting one in a bend alongside something you have to stay clear of is a situation to plan out of the day rather than handle when it arrives.
288 charted depth areas and 296 depth contours, seventh and eighth of the fifteen rivers. That is a fine division of the bottom for a river of this size, and the reason is that the bottom here behaves in a particular way. Between the dams the level is a managed thing. It does not answer to the moon. It answers to what the dams are holding and to what came down the watershed last week, and those two can put the same stretch of water into two different moods inside a day.
12 charted wrecks, eighth of the fifteen. Twelve is a small enough number to treat as background noise, which is exactly the mistake. On a working river the things sitting on the bottom are the things the work left behind, and they are not spread evenly along the reach. Where the depth shading itself comes from is a separate subject, and Helm keeps that explanation on its depth page instead of hiding it.
These counts describe what the chart pack carries, not the state of the river today. Charted data ages, pools change with the dams, and a lock can be out of service. Keep a lookout, listen to the traffic, and verify locally.
The Allegheny pack carries 118 charted bridges and 41 overhead cables, 159 crossings in total over the reach it covers. Set your air draft once and the charted vertical clearance on each of them is checked against that figure. The cables are the ones to look at first, since a cable has no schedule and nothing to open, so the charted number is the only room you are going to get.
The pack carries 21 charted lock features, eighth of the thirteen rivers Helm charts that have any. That count includes chambers, gates and dams as separate items, so it is not a count of lock sites and should not be read as one. C.W. Bill Young is among the names carried in the chart data for this river.
The pack covers the river from 40.44 N at the junction upstream to 40.90 N, and from 80.01 W east to 79.47 W, and the whole thing downloads at 1 MB. The Monongahela and the Ohio are charted as their own packs, so a trip that runs through the junction means carrying more than one.
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