R109LM Depth/Temperature Transducer

Part # R109LM

The R109LM is a urethane, thru-hull CHIRP transducer, ideal for sportfishing and commercial vessels up to 12 m (40 ft) in length. This dual-channel transducer combines Low CHIRP frequencies to accurately track the bottom in deep water, and Medium CHIRP for greater resolution with minimal loss of depth penetration. 

Key Features

  • 38-75 kHz Low CHIRP with 19-10° port/starboard beam width (10-5° fore/aft)
  • 80-130 kHz Medium CHIRP with 13-8° beam width
  • Up to 1200 m (4000 ft) range with Low CHIRP
  • 16 internal broadband ceramics
  • Thru-hull with urethane housing, stuffing tube and high-performance fairing (can retrofit to existing R99 installations)
  • Suitable for fiberglass, wood and metal hulls
  • Ideal for sportfishing and commercial vessels up to 12 m (40 ft) in length
  • Recommended for use with the BSM-3 broadband sounder module
Where To Buy

    Dual Channel CHIRP

    Using pulsed transmissions swept across a range of frequencies, CHIRP technology delivers target resolution and depth penetration superior to traditional single-frequency sonar. This dual-channel CHIRP transducer operates in the 38-75 kHz Low CHIRP frequency range with a 19-10° port/starboard beam width (10-5° fore/aft), and the 80-130 kHz Medium CHIRP frequency range with a 13-8° beam width. With Low CHIRP, the R109LM provides an operating depth of up to 1200 m (4000 ft).


    One sensor does it all. Able to measure both depth and temperature in a single package, the R109LM simplifies installation and requires just one connection to your echosounder module or multifunction display.


    With urethane housing, the R109LM is suitable for thru-hull mounting in fiberglass, wood and metal hulls. Thru-hull mounting places the transducer in the water on the outside of your boat’s hull; a hole must be drilled for installation, and a fairing block is required to ensure proper alignment. This typically offers the best depth measurement and fishfinding performance.

    Calculate the beamwidth for this transducer

    R109LMFrequencyCone AngleBeamwidth
    80 kHz 13°  
    130 kHz  
    38 kHz 19°  
    75 kHz 10°  
    Depth: Update
    NB: depending on the strength of your transducer pulse