Easy to Use Portable Echo Sounder or Depthmeter

by OldSailor on March 24, 2008


Sound waves are used for depth measurements. The reason is:

The speed of sound in air is 344 metres/second. But interestingly the speed of sound in water is about 1500 metres/second though the speed of sound in water depends on water pressure,temperature,salinity. Electro Magnetic (EM) waves are used in Radars due to their high speed (equal to speed of light) in air. But, EM waves are not suitable for use in water as attenuation in water is very high.

Echo sounders (depth meters) are installed in ships as a navigational aid for depth measurement of the sea. Same sound waves are used in Sonar.

Portable sounders or depth meters are necessary for those who are interested in boating, fishing, scuba diving, coastal survey, and scientific work.

Here is an easy to use SM-5 Depthmate Portable Sounder from Speedtech Instruments.


  • reads in feet or metres to the nearest tenth through a solid hull, inflatable bottom, or black ice but can not read through air.
  • 200kHz with 24ยบ beam angle
  • has a backlit display and the readings are displayed for ten seconds.
  • waterproof up to depth of 160 feet or 50 metres
  • can measure depth up to 2 to 260 feet or 0.6 to 79 metres
  • uses Standard 9V dry cell battery for operation and lasts for 500 readings
  • pocket sized, dimensions: 7.7 x 1.7 inches (198x42mm)
  • easy to carry, weight: 10 oz / 300 grams

If it is not easy to reach water surface with SM-5 for depth measurement, here is SM-5A with external Transducer.


SM-5A is supplied with 12 feet wire with an external transducer at the end. Though the transducer fitting is waterproof, it is not for underwater use and cannot be submerged.

Source: Speedtech Instruments

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{ 4 comments… read them below or add one }

Joga Appala Raju September 27, 2012 at 9:12 PM

potable echo sounder
for sea depth measurement
up to 0 to 100mtrs

Joga Appala Raju September 27, 2012 at 9:14 PM

portable echo sounder
for sea depth measurement
up to 0 mtrs to 100 mtrs

dirk de Cock February 22, 2014 at 3:31 PM

Dear ,
where can I buy the SM 5 dept mate please.

Doriedson February 2, 2015 at 6:02 PM


I would like to get a budget for SM-5 for depth measurement.

Thanks in advance.

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