Swoffer Instruments, Inc has been manufacturing water velocity related instruments since 1959. Beginning then with the first electronically operated sailboat speedometer and continuing to expand into open channel velocity measurement. The Model 2100 instrument was introduced in 1980 and has been one of the most reliable water current measuring instruments in the US. The newest addition is a data logging flow meter - the Model 3000 .

The basic principle of the Swoffer fiber-optic sensor is simple and unique: Multiple bundles of fiber-optics, assembled into a propeller driven rotor, gate a beam of infrared light from a photo diode to a photo-sensitive transistor producing electronic pulses. These pulses, generated by the propeller rotor over a precisely measured amount of time, are directly proportional to water velocity.

The electronic half of the sensor is the latest opto-electronics and is epoxy encapsulated in a ½" (12.7mm) diameter acetal resin housing for protection from chemicals and the elements. It can be purchased separately and attached to and used with many in-water devices in addition to those offered by Swoffer. The sensor uses a two-wire signal system requiring only 3 volts for operation and can generate an output signal through over 1000 feet of cable.

The rotating portion of the sensor consists of a very low friction fiber-optics rotor rotating around a polished & hardened stainless steel shaft, all driven by a glass-reinforced nylon propeller. All rotor parts are easily replaceable in the field and spares are provided with every new instrument.

Swoffer Model 3000 Current Velocity Meter-Flowmeter       

• Read stream velocity directly from 0.1 to 25 feet (.03 to 7.5 meters) per second in Velocity mode
• Records depths, widths, velocities, flow angles, time/date ("stations") in "Discharge" mode
• Memory holds 1000 "stations" in up to 100 cross sections for later upload to a PC
• Calculates discharge
• Velocity sampling interval is user selectable from 1 to 999 seconds
• Calibration ratings for 10 different sensor options are stored and can be edited
• Powered by four AA size batteries
• Designed to function with Price type AA and Pygmy meters with or without optic sensors
• Can be easily field-calibrated to operate with any contact closure type sensor

• Read stream velocity directly from 0.1 to 25 feet (.03 to 7.5 meters) per second
• Velocity displayed in either feet or meters per second
• Three selectable pre-set display update times. 90 second maximum
• Powered by a single standard 9V battery.
• Uses the efficient, propeller-driven Photo-Fiber-Optic sensor pioneered by Swoffer in the 1970's
• Precision quartz crystal controlled electronics provides accurate, precise data in all flow conditions