AbstractAsignificantly improved conceptand technique of sonar ranging has been developed by the Deep Tow group of the Marine Physical Laboratory. This OFFSET technique resolves the multiple sweep ambiguity encountered in precision sonar ranging with graphic recorders by the temporary use of a small relative change of sweep rate. Using the OFFSET technique, high resolution and precision are maintained during the gross range measurement. These are obtained and displayed permanently with one recorder. Compared with conventional methods and their limitations, the advantages of OFFSET, as well as its simplicity of operation, make it a worthwhile, easily implemented extension of the graphic recorder. Echo sounding and acoustic transponder data taken at sea substantiate the usefulness and applicability of the OFFSET method to echo sounding and acoustic navigation problems.