dybdemålere
Dybdemålere, often translated as depth sounders or echosounders, are instruments used to measure the depth of water. They are fundamental tools in hydrography, navigation, and marine research. The most common type of dybdemåler operates using sonar technology. A transducer emits a sound pulse, or ping, into the water. This pulse travels downwards, bounces off the seabed, and returns to the transducer. The dybdemåler measures the time it takes for the sound pulse to travel down and back up. Knowing the speed of sound in water, which varies with temperature, salinity, and pressure, allows the instrument to calculate the distance to the seabed, and therefore, the depth.
Early dybdemålere were mechanical, using weighted lines. Modern electronic dybdemålere are far more accurate and efficient.