Ahoj!

Anybody out there with experience in creating maps of canals?
I'd like to create one of a piece of the so called "Mittellandkanal" (en.m.wikipedia.org/wiki/Mittelland_Canal).
It's shape is either trapezoid with stone packing or rectangular with steel pilings on either side.
The width differs from 40m to 55m.
The depth in average is about 4m everywhere.

In this (at the first sight boring) kind of waterbodies small holes and underwter changes of the structure - which may result in a height difference of only 50cm - are not seldom and they also are interesting for fishing of course.

What do you think is the best way to log the data? What transducer technology? Which frequence is best to be used? What distance between the tracks? Is it possible at all to generate a highly detailed map of a shallow canal like this?

I thought to spend some money on a lowrance or simrad with totalscan and a reefmaster license. Good idea or just wasted money?

Thanks in advance for your tips & tricks & knowledge!

Pixelpussy.

I'm interested in what the experts recommend for your mapping project. I use ReefMaster for something completely different -- mapping the coral reefs we dive on in Fiji -- but I have a similar issue in that the sheer drop-offs tend to map as slopes rather than vertical surfaces. I use a Lowrance Hook 5 and I'm hoping someone can suggest the best settings to avoid the averaging that I presume accounts for my issue. Thanks and best fishes, Rob

@pixelpussy

I added to my maps details of underwater objects using hand drawn polylines. I use mosaic images taken from my recordings (sidescan) and draw lines around the objects.
First image shows a local wreck which has been blown up as it was a hazard to shipping. It doesn't stand up very high so Reefmaster doesn't draw contours around it.


Second image shows a dredged shipping channel. The blue lines are the dredge marks.


This is a fair bit of work but I now have a map that has steep ledges, rocks, wrecks, artificial objects, etc all marked for my own use in my plotter.

@pixelpussy

In your case you must drive in longitunal lines as narrow as possible. Please also visit the homepage:

www.tacklefever.de/index.php?topic=5273.msg40415#msg40415

(This is also the german RM forum)

Note, that you can receive the shorelines and other datas from the WSV (administration). But this required a bit GIS knowledges.

www.wsv.de/service/karten_geoinformationen/index.html
www.elwis.de/Service/Inland-ENC-der-WSV/index.html

As it seems your goal is to have your map show even minor differences in depth, I would NOT recommend TotalScan for your project. TotalScan has a coneangle of 22 degrees at 200 kHz, and that is to wide to pick up on minor changes in depth like potholes etc. You need a ducer with a narrow cone for this. Airmar TM260 would be ideal, but quite expencive. :) Airmar P66 or Lowrance/ Simrad HST-DFSBL are almost as good as TM260 in shallow-ish water with their 11 and 12 degrees coneangle and at a much lower price.

Combine that with LSS-2 or even better StructureScan 3D and you are good to go.