The CM2 product family

CM2 Digital Towfish

The CM2 family of towfish includes two dual frequency models, types DF and EDF. These cover a total of three acoustic frequencies, namely 100kHz (LF), 325kHz (HF) and 780kHz (EF).

For most search and survey tasks the DF towfish is the most useful. In LF mode the search swath is up to 1000m wide, useful for searching for larger objects such as wrecks or freight containers. In HF mode it is usually possible to distinguish such objects as mooring ropes, anchor chain, anchors, scour marks, pilings, crab pots, rocks (down to the size of a briefcase or less), as well as differences in seabed texture.

Towfish on blue background

The CM2 Digital towfish. Specifications

The EDF towfish is primarily for tasks that may require the highest resolution. Like the DF towfish it offers HF operation out to 150m. However instead of LF in this towfish the HF frequency is paired with EF (780kHz) frequency. EF is only capable of short ranges but gives the most detailed images. EF is, for example, useful for positively identifying an object first located in HF.

Note that the complex HF sonar transducer configuration in both types of towfish is unique to C-MAX. It produces powerful, flat-topped transmit and receive beams complemented by additional coverage below the towfish. This gives wide high quality images and enhanced immunity from surface reflections.

Towfish beam detail

C-MAX's unique towfish beam pattern

All of the towfish models feature:

All CM2 towfish are powered from the surface via the tow cable.

(Note that some sidescan sonars advertise the fact that they offer "simultaneous" dual frequency. This ability is an incidental outcome of the way in which the early dual frequency sonars were designed and the simultaneous operation has no practical value. The CM2 uses the best frequency for the task in hand and does not clutter the recording medium with redundant data.)