The Simrad SAL R1 / SAL R1a Easy Tank is an IMO type-approved, single-axis Speed Through Water (STW) log engineered primarily for commercial vessels. Developed by Consilium (SAL) and distributed under the Simrad Commercial portfolio, it utilizes Acoustic Correlation sonar technology instead of conventional electromagnetic or Doppler mechanisms.

Operating Principle: Acoustic Correlation

Unlike Doppler logs that require geometric angular corrections or electromagnetic logs that sample water directly adjacent to the hull, the SAL R1 transmits ultrasonic pulses ($3.8\text{ MHz}$ and $4.2\text{ MHz}$) across two parallel elements inside a single transducer. By measuring acoustic noise patterns approximately $130\text{ mm}$ away from the hull surface, it bypasses the turbulent boundary layer, yielding exceptionally stable speed readings across the full speed range.

Key System Features

• “Easy Tank” Bottom Arrangement: Closed-ended installation design that eliminates the need for expensive watertight compartments, cofferdams, or piping extending above the waterline.

• No Moving Mechanical Parts: Low-profile, flush-mounted transducer mounted from inside the hull.

• High Pressure Rating: Pressure tested and rated up to PN16 (24 bar / 240 m).

• Material Options: Bottom flange arrangements available for both steel and aluminum hull constructions.