Tonpilz-type transducers are highly important for sonar systems to generate and receive sound waves. They are generally used for low frequency applications. This study covers designing, manufacturing and characterization of Tonpilz-type transducers which is intended to operate below 7 kHz in hull mounted sonar systems. Transducers are first designed using simple lumped parameter, equivalent circuit and finite element methods according to the acoustic specifications obtained from original prototypes. Two transducers are then specified by considering the predefined specifications and finally manufactured. The T1 and T2 transducers both have an operating frequency of 4.9 kHz with a mechanical quality factor of 3.5. Maximum TVR levels are 133.7 dB//1 mu Pa/V for the T1 and 137.3 dB//1 mu Pa/V for the T2. Maximum RVS values are -159.1 dB//1 V/mu Pa at 4.9 kHz for the T1 and -156.8 dB//1 V mu Pa at 5 kHz for the T2. According to the accuracy of the results, FEM was the best one among the design methods. Acoustic parameters are highly satisfied for the T2 transducer when compared to the original prototype such that the operating frequency (f(p)) is 30% lower, the TVR values are almost the same and the RVS is 3.2 dB//1 V/mu Pa higher. These results suggest that designed transducers can be successfully used in the currently-utilized hull mounted sonar systems due to their comparable acoustic parameters attained at much lower operating frequencies. (C) 2019 Elsevier Ltd. All rights reserved.