looking to make charts

100' dinner boat on a non-navigable river with no charts. Sounds like your theme song should be Giligan's Island. Can't help you with the software, but You could simply run a track on your Garmin and waypoint a route or the shallows. Mind you to note the river height and keep in mind the flood/dry cycle. What's good after the spring thaw may be garbage in September.

what i've done a few times in the bahamas when looking at poorly charted areas is take the tender with a portable GPS and look for the deeper water then mark some waypoints once I had found the best route. In most areas you can read the waters but there are some route on the bank which were tight and 2 feet made a difference.

once I had the waypoints in the portable, the first time I ran it on the "big" boat I used the portable then marked the WP on the on board plotter and computer.

If you want to mark the depth, something like OpenCPN allows you to drop some marks on the chart with various icons and whatever caption you want, in your case, depths.

Trouble with rivers is that in most situations that's not the case. You also need to chart them at a low point in the cycle because the hide surprises. You can well have a nice deep area and in the middle find a tree stump or rock, or a whole tree. In fact, after the floods of the past few years you can find houses, cars and trucks. A fish finder, more than a depth finder, could be a real asset in this project. Hate to roll through a deep spot checking with a depth finder, not knowing there's an oak 3' to your side. Given the distance a 100' dinner boat travels on a 4 hour cruise you've got a real project there.

You might try contacting some of the people who have done just that. Like Nigel Calder or the folks who put together the Explorer Chart books of the Bahamas, Monty and Sara Lewis. Then there is Steve Dodge who does the Guide to Abaco. I'm sure some of them would be willing to tell you how they go about it.

I was obviously referring to the bahamas not muddy rivers...

Richardsons or the Army Corp of Engineers doesn't make a chart for your area and Lake Michigan? I've found Richardsons to have charts for the just about every nook and cranny in the Great Lakes.

Nice web page Cap, but tell your co-cap that he needs to stay away from that good food . From your original post I envisioned a backwoods area. Now I've Google Mapped the area and that's not the case. This is an improved waterway with a dam and I suspect that the Army Corp of Engineers will have at least a rudimentory map (probably not a chart) of the area showing the general depths and flood info. I didn't note any warning buoys marking the dam (although I may have just not been able to see them). If there're are none that may not bode well for your navigating that area, but the Corp should be able to give you pretty good info.

If ACE has been through there, it will be marked with nav markers in the water and a rough, but not non-existent chart. At least that's been my experience in Michigan lakes and rivers. Lake Michigan, as well the others are very well charted. Useless once you get to an interconnected lake, or feed river. Charlevoix is fairly well marked. Same with Muskegon, and Spring Lake. But the markers (if they're there) in the rivers to and from are minimal.

Your best bet would be to take a weekend and plot a course in a smaller boat, marking your waypoints as suggested earlier. You can transfer that as a route to your on board nav system depending on what you have, or overlay it on an existing map / chart / sat image.

We use Coastal Explorer by Rose Point which works well for overlaying. OpenCRN does a nice job as well.

You could manually do it with each waypoint, it's just a time consuming process.

I'm actually surprised that the river from Grand Rapids to Spring Lake / Grand Haven isn't marked.

What other lakes / rivers are you looking to chart? I'm in S. E. Michigan now, but our boat stays in the W. Michigan shores anywhere from Grand Haven to Harbor Springs through the summer.

be your own cartographer

I remebered

MaxSea has build a Personal Bathy Generator for autogenerating charts.
I would try this.