Properly install your Lowrance/Simrad transducer and mapping is easy with BioBase.

Ray Valley

Aquatic Biologist and BioBase Product Expert

BioBase’s EcoSound is a powerful cloud platform for creating high definition lake or coastal maps of depth, aquatic vegetation (or seagrass), and bottom hardness from Lowrance® and Simrad®

sonar systems. For the user, the process of converting volumes of raw sonar and gps signals into an intuitive map is easy and requires very little input upfront. Record your sonar while out on the water to a microSD card, plug the card into your PC back at the office, log into your BioBase account and upload. Algorithms on remote servers do the rest of the work. However, one of the most frequently overlooked parts of this equation is careful attention to the proper installation of the transducer sensor that is pinging the bottom and collecting all the information below the boat. The importance of proper transducer installation cannot be overstated. If the transducer is not properly placed on the boat or not at the appropriate angle, your BioBase outputs could be inaccurate. Modelers have heard it said many times (sometimes in more colorful language), the quality of the output depends on the quality of the input.

A common challenge…

Given all the unique boat hull designs, this issue is not unique to BioBase and anglers flood online message boards, social media groups, blogs, and YouTube to ask and learn about how to properly install their transducer in order to get the best picture of bottom so they can find and catch more fish. Almost all installation problems fall into 4 categories: Transducer is too low, too high, not angled correctly, or placed in a spot on the boat where interference with water flow is high. I’ll look a little closer at each of these issues. Before I go further, I should mention that the most common placement for transducers (for anglers, small craft boaters, and BioBasers) is on the transom of the boat, so examples below are focused on that placement.

Transducer is too low or too high

If the transducer is placed too low on the transom, significant turbulence will occur around the part of the mount that is below the boat hull. This will cause plumes of interference near the surface of the water, create “rooster tails” at high speeds, lose bottom lock, may cause false vegetation detects by EcoSound algorithms (Figure 1).

Figure 1. Example image of a transducer that is installed too low on the transom of a boat. Bottom tracking could be affected due to water bubbles (cavitation) caused by the transducer mount interfering with water flow.
Figure 2. Transducer height is perfect. Water flow off the hull of the boat and across the transducer face is smooth (laminar flow)
Figure 3. Use a level and straight edge to gage the proper angle and height
Figure 4. If the transducer is placed too high, interference from cavitation will also occur. Another challenge with airboats is managing vibration from the engine/fan.

Transducer is not angled correctly

Sonar transducers emit a flashlight-like beam (traditional “broadband” sonar) or an elliptical copy scanner-like beam (Down- and Side-scan) while pinging. So, in the parlance of a flashlight, the angle you have that beam pointed affects what area is “lit up” and how strong the beam is. If it’s angled away from your target, obviously, the picture you see on the Sonar screen (and thus the mapping algorithms) will be affected (Figure 5).

Figure 5. Transducers should be level on a flat bottom. If you have an improperly angled transducer then accuracy of BioBase EcoSound outputs can be affected. Watch for evidence of a tilted transducer while recording your sonar. If the thickness of the color of bottom seems to depend on what direction you are going, then its likely the transducer is tilted.

Use a torpedo level…and coins

Another commonly overlooked issue is that the angle that the boat sits loaded up with people and gear in the water may be different than how it sits on the trailer in the shop or garage. BUT, there’s a super easy way to account for that! Grab a handful of coins, a torpedo level and see below or watch this video.

Figure 6. Stack coins under one side of your torpedo level on a flat area of the boat when on the water and loaded. Note how many coins are needed to level. Back at the shop, put the same coins under the same level and crank up or down the boat trailer jack until level. Square up the transducer at that trailer angle.
Figure 7. Assuming the boat does not lean port or starboard on the water, make sure you level in the left/right direction as well. And one final thing…you see all those holes around the transducer mount? Do yourself a favor and install a $15 transducer mounting plate rather than making swiss cheese of your transom. Your boat’s lifespan will likely span many different transducers that may require different holes.

Transducer placement on transom

Due to the huge range of hull sizes, designs, and motor mounts, this last issue is the most difficult one to be formulaic with a nice “do it this way” picture. If you can, try to mount the transducer no closer than 15″ from your lower unit. If you can, keep it out of the path of rivets, strakes, or any other feature of your hull that could interfere with the smooth, laminar flow of water. If you can, keep it away from bunks and straps. Lot’s of “if you can’s” and sometimes you can’t. Therefore, do your best, mount it up (again on a transducer mounting plate), and see how it goes. You will likely need to do some tweaks, but once you get it, you got it (Figure 8)! Lock it down! A properly mounted transducer should hold a bottom lock on most boats up to at least 40 knots. I am not a fan of portable transducers because there are too many points of failure and difficulty of getting it exactly the same each time you install it. Compared to the display, transducers are relatively inexpensive. If you need to outfit multiple survey boats but don’t have the budget for multiple displays, purchase multiple transducers, “permanently” install them and port your display to where its needed

Figure 8. Example of very clear sonar imagery that indicates a quality transducer mount. Note a solid bottom signal (yellow) and minimal surface clutter/noise at the surface.

Avoid side-scan interference

When you install your side-scan capable transducer envision the beam pattern of the schematic below in the location you would like to install your transducer. Will any of those beams hit an obstruction like the outboard lower unit or another transducer. Adjust the transducer so all beams can intercept the bottom unimpeded. Look for strange anomolies in the side scan image [shadows, suspended non-moving objects, different contrasts of colors on opposing sides despite a flat bottom (suggesting the transducer is tilted side-to-side)]

Schematic from US Patent US09268020-20160223-D00008 showing the design of Lowrance side-scan beams looking. Ensure these beams do not intercept any accessory on the boat (e.g., outboard lower unit)

Additional video resources:

Demo of properly installed Lowrance TotalScan (also translates to more recent Active Imaging 3in1 model)

Click Here for additional help with BioBase EcoSound and EcoSat products.

Author: biobasemaps

BioBase is a cloud platform for the automated mapping of aquatic habitats (lakes, rivers, ponds, coasts). Standard algorithms process sonar datafiles (EcoSound) and high resolution satellite imagery (EcoSat). Depth and vegetation maps and data reports are rapidly created and stored in a private cloud account for analysis, and sharing. This blog highlights a range of internal and external research, frequently asked questions, feature descriptions and highlights, tips and tricks, and photo galleries.

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