Wireless sensor network for the accurate measurement of yacht freeboards

Measuring the freeboard height is fundamental for boat builders and hull designers, because it provides precise information about the ship´s displacement as well as its trim when floating, but no electronic system to carry it out is available. We describe here a wireless sensor network, consisting of three magnetostrictive level sensors, an inclinometer and a central unit, that automatically performs the freeboard measurement, otherwise realized with manual meter readings, with large improvement of the measurement accuracy that is estimated around 1 mm. The level sensors have been battery powered and provided with a wireless connection to act as slaves of a Bluetooth piconet. The experimental results that show the functionality of the system and its great potential in extracting many useful information from the acquired data are also shown.