The Speedtech Depthmate SM-5 is a handheld echo sounder which measures distances through water, either directly or through the bottom of a boat. It will give an accurate reading up to a distance of about 80 m.

Also available is the Depthmate SM-5A but with an external transducer complete with a 12-ft cable.

Use the handheld echo sounder in conjunction with a GPS to produce rough topographical maps of lakes and shorelines - useful for surveys. For example this kind of information would be useful for a macrophyte survey to see which plants live at which depths.

You could also use the Depthmate SM-5 handheld echo sounder when diving to measure horizontal distances such as from a wreck site to the shore - or to the rock on which it crashed.

Depthmate is waterproof to a depth of 50 m and floats.

The transducer in the end of the unit must touch the water or a solid surface which is in the water, e.g. air-free hull, inflatable bottom or black ice. Sonar will not read through air.

Readings are accurate from 0.6 m to 79 m, measured in metres or feet to the nearest tenth. A reading holds for 10 seconds or updates each time the switch is pushed and the digital display is backlit for readability..

The 9 V battery will power 500 x 10-second readings.

• Dimensions: 4.2 x 19.8 cm
• Weight: 300 g with battery
• Frequency: 400 kHz
• Beam angle: 6°
• Power: 9 V battery (±500 readings)
• Units: feet or metres
• Depth scale: 0.6 m - 79 m
• Water resistance: waterproof to depth of 150 m; this unit floats