There will come a time when you are going to want more detail and accuracy from your maps. Unlike the Great Lakes of the United States and hundreds of others that are mapped in the greatest of detail, we have very little. The solution to this problem is bathymetry, namely the study of depth. Due to advancements in the bathymetry industry, you no longer need to buy a survey vessel, a couple of million Rands worth of hardware and a software package the same price as your first house in order to create your own detailed maps. Many of you might already have Sonar Logging on your sonar/GPS unit and just never realized it.


Sonar logging records longitude, latitude, depth, temperature, bottom type, and a host of other variables. This information is saved to a removable memory card that can be used in a number of ways on your PC. The first of which is using SonarViewer, this is free software available from Lowrance that effectively plays the entire recording back on your PC like a video, with play, pause, stop, FF and rewind. If you see something interesting you can pause, place your mouse pointer over the point of interest and a window will appear giving your cursor depth, bottom depth, position, date and time.

Bottom Hardness in 3D

The next thing you can do with this recording is to convert it to a 3D bathymetric object using a program like DrDepth that only costs around the same as a handful of crankbaits. This program can also convert these maps to a Lowrance Chart Map, or LCM as it is known. You can now create high definition accurate charts that can be customized in many different ways. These charts become the background of your Lowrance / Eagle unit, with all your existing waypoints, routes and trails on top of the chart.

The BT version of this software allows you to create a bottom type chart from the same recording. This is the most effective way of finding those hard bottom areas that we know bass love. These bottom type charts can also be viewed in 3D giving you a better idea of how the rocks are positioned on a drop off for example

Another fantastic aspect of this tool is that you can now effectively ‘cruise’ around your local dam while sitting at your desk at work or home, planning how you are going to target the dam in future by saving waypoints and creating new contour routes. This information is saved to a memory card and simply loaded to the sonar / GPS unit. If you are prepared to carry a laptop with you on the boat, or using the Mobile version of DrDepth on your Smartphone, you can now monitor your actual position in relation to the exact spot on the bottom in real time through the NMEA0183 com port.

Side Scan Sonar

The next step to contouring is to start recording key structures such as rocks, trees, lay downs, brushpiles and man made structures such as old buildings, walls, jetties, tyres etc. that bass so often tend to hang around. Looking for this unique structure can be a little bit like trying to find a needle in a haystack, but this is not the case if you have high frequency side sonar, like that of the Lowrance StructureScan or LSS-1. Side sonar is like having a camera with a range of up to 200ft on either side of the boat. Once something unusual is detected, the cursor can be placed over this unique structure and a waypoint is taken. You can now navigate directly to this waypoint, be it to the left or right and now use the wide 60° beam of the 83kHz Broadband to scan over and around the structure for lurking predators.

Baitball in tree with predators

Until just recently it has been very difficult, if not impossible, to determine if structure, like a tree for example is holding fish directly in it or not. This is due to the umbrella-like effect the echoes create with conventional 83/200kHz cone shaped sonar. But now with DownScan’s razor sharp beam you can see what is happening in the tree basically from branch to branch. This makes it very easy to not only spot where in the tree the bigger fish are holding, but to also see if that structure is holding food for these bass, such as bait balls.

Incredible Detail using DownScan

Fishing is a game of chance. Imagine every cast you make as a pull of the lever on the old ‘one arm bandit’ in the casinos. The problem with gambling and fishing alike is that you need to generally make a lot of ‘casts’ to all the structure hoping that the next one will be the one, then the next one, and so forth. Now imagine if you had a device that by merely walking past the hundreds of machines on the casino floor, will accurately point out the handful of machines that are most likely to ‘pay out’.

High Definition Fishing Charts

Adding this data to your contour maps effectively creating ‘hotspots’ along the way is like adding stop-over points to your map when doing a long road trip. Knowing the precise moment when your lure will be in the strike zone within an overall strike zone, will give you the absolute best opportunity of getting that fish of a lifetime. You have now effectively traded that white cane in for a ‘military grade’ fish finding ‘weapon’!

Easy on-board filing system

Having the ability to capture all this amazing data is one thing, but how do you actually use all this information effectively? If we all had a photographic memory then this would not be a problem, but since this is not the case, we need a good filing system for all this info. Nothing beats the good old fishing logbook, but when you have been fishing for many years it becomes a bit tricky trying to remember in which book is what info, and accessing it quickly becomes a problem. The Lowrance HDS has a filing system similar to Windows Explorer, so you can now save up to 32GB of data on to a SD card with every bit of fishing data imaginable. Each dam can be broken down into areas, and under each area a separate folder for 1. Images, 2. Log Book Data and 3. Sonar Screenshots or even sonar log playback like a video.

Follow pre-set contours with i-Pilot and DrDepth

With all this amazing info and technology available, there is still one weak link to contouring accurately all the time, and that is human error. We either forget what certain waypoints are, or we get distracted or the wind blows us off course, but the fact remains the same – we did not follow the route or contour with 100% accuracy. Minn Kota has a solution to this - it is a true Auto Pilot that has just been launched called i-Pilot. It fits to your Terrova, PowerDrive or RipTide trolling motor and can be used either on its own, or with DrDepth to follow a set path with amazing precision. It can also effectively be used as a ‘hand brake’. What I mean by this is that if you find a piece of structure loaded with fish that you would prefer to stop say 20m from, at a bearing of 234° in relation to this hotspot for example, and fish by means of conventional cast and retrieve, you merely tell the i-Pilot to hold you there. This allows you to concentrate 100% on your fishing, and leave the fiddling with the trolling motor against wind or swell to the i-Pilot.

With a bit of time and patience, this technique will get you some really good fish any time of the day throughout the year.