The biggest impact on the vessel’s mean draft value has a correct readout of immersion at an amidships. That is why, we should strive for the most accurate determination of that parameter. Many factors affect the correct readout of immersion, e.g.: swell, pitch and sway of the vessel. Therefore, based on years of experience in draft surveys, we had developed a special device to measure the freeboard of the vessel. It allows to remove much of the errors in the determination of amidships drafts.
The device has a special tape, which is used to measure a height from the reference point (usually the line of the upper deck line) to water level and sensor. Sensor is activated when the „0” point at the tape will appear on the water level, and it is emitting a sound and a light signal. The device is constructed in such a way, that fluctuations of the water level inside the sensor are as small as possible. It allows to reach a measurements accuracy (approximately 5mm), even with a heavy sea condition during measurements.