The transducer connected to your Lowrance echosounder plays a critical role in producing quality map outputs. Fortunately, the mechanics of producing quality hydroacoustic signals has been honed by 57 years of research and development by engineers at Lowrance. Still, users play an important role in optimizing outputs by selecting the correct transducer and installing it correctly
Selecting a Transducer
There are several resources that can help you choose the correct transducer. Although it hasn’t been updated recently, Lowrance has an interactive site that demonstrates the size of bottom that is scanned at different depths for different frequencies and transducer models. One very common transducer for Lowrance HDS for inland applications (both fishing and mapping) is the dual frequency 83/200 kHz skimmer® broadband transducer (model HST-WSBL). This is a popular transducer due to its small size, low cost, ruggedness, and reliable performance. The transducer elements from the HST-WSBL have now been integrated into transducers that include down- and side-imaging (e.g., HDI, TotalScan, Active Imaging 3in1)
Still, Navico and our partners at Airmar Technology Corporation offer a wide range of compatible transducers for Lowrance and Simrad multi-function displays. See the Lowrance Store for a full range of options. Thus, the advanced user has a range of options to customize their setup to their use cases (e.g., inland vs offshore, small shallow ponds vs large deep lakes; Figure 1).
|Figure 1. Airmar TM260 narrow-beam dual frequency transducer (left) and the much smaller Lowrance HST-WSBL dual frequency wide-beam skimmer® transducer (right). Ping pong ball is displayed for scale.|
BioBase mapping outputs are currently optimized for the 200 kHz broadband frequency. But users have the option of choosing narrow (6-deg), medium (12-deg), or wide (20-deg) beam angle transducers. The beam angle determines the size of the acoustic footprint of each pulse and thus the local sample area (Figures 2 and 3). Most Lowrance HDS Sounders for use in inland waters come equipped with the wide-beam HST-WSBL transducer.
Although the TM260 and HST-WSBL represent both ends of the spectrum in terms of beam angle, both tracked bottom depth similarly (within 6″) in aquatic plant environments in recent tests on a Minnesota lake (Figure 3). Thus, in most common shallow-water circumstances we may expect similar map outputs with both narrow- and wide-beam transducers.
Types of Mounts
There are a range of options for mounting your Lowrance or Simrad transducer that we discuss and demonstrate in a popular blog published in 2013. In Table 1, we list the major types of mounts BioBase users deploy to survey aquatic habitats.
*Shoot-thru mounts with pliable, puddy-like duct-seal are portable, Shoot-thru mounts with epoxy are permanent.
**For this analysis, scupper-hole transducer mounts are considered “bolt-thru” but are not permanent
For the highest quality outputs and most reliable performance, we recommend the bolt-thru transducer mount, especially for high-use, dedicated survey vessels. The transom mount is recommended as a high quality, flexible option where a permanent mount is not feasible. However, misalignment of a transom-mounted transducer is a common issue that is often overlooked.
Importance of Proper Transducer Alignment
A transducer that is not parallel with the ground can result in inaccurate depths, vegetation detection, and bottom hardness estimates (Figure 4).
Although properly aligning your skimmer® transducer seems simple to accomplish (Figure 5), boat transoms are often a vulnerable place for a transducer to be and can be knocked off alignment by a variety of unintentional actions (e.g., trailer loading, obstructions in water, etc.). Often a misaligned transducer can escape the notice of even the most skilled operator.
Monitoring your SONAR page while recording and correcting issues quickly when they arise is the best way to ensure high quality BioBase maps. If you do suspect that your transducer is misaligned while recording, first stop recording, adjust your set up, test, and then begin recording again. Make note of the filename where you observed the problem and you can later edit your output in BioBase if the file was only partially affected. If the entire file was erroneous, avoid uploading to BioBase and merging it with other files
Get Expert-level Map Outputs By Only Following a Few Easy Steps
Advances in consumer sonar and gps technology coupled with automated cloud computing has removed a great number of prerequisites for creating high quality aquatic habitat maps. Yesterday, practitioners were required to possess a great understanding of the fundamentals of hydroacoustics, GIS, and cartography and had to calibrate their hardware by precise “knob-turning.” Today, with Lowrance and BioBase, you can grab a Lowrance HDS off the shelf, take some care installing your transducer, record your sonar while on the water, upload to BioBase, and high quality maps will be produced automatically. Contact us at firstname.lastname@example.org for a free demo!