Need Help : Measuring Fiberglass thickness by using Ultrasonic distance sensor

I work in my final project. I willing to design thickness measuring device by using ultrasonic distance sensor. The purpose is measure the thickness fiberglass fishing boat's hull. The thickness hull can be measured by using ultrasonic transducer. The device already available in market. But, My ideas is measuring the fishing boat hull thickness by using ultrasonic distance sensor. The logic is, place the ultrasonic sensor in one edge and place barrier in next edge. Then, calculate the distance between barrier and ultrasonic sensor. Then , keep the object (which thickness we need to measure) between ultrasonic sensor and barrier. The object should be keep with barrier. After that check the distance between object and ultrasonic sensor and marked it. Then, finally we can measure the thickness of the object by subtract first measurement from, second measurement. My problem is , i unable get final result (object thickness) in one time. So, If anyone can know how to find thickness of object , Please share your ideas.


Are you using a common ultrasonic rangefinder module?

Can you post your code and a drawing of your setup?

What resolution and accuracy are you expecting from the measurement?

I admit that I don't understand your design. But what's the delay between the sent and received signal? When the speed of sound allows to measure distances of several inches with an Arduino, it will become much more complicated with small (hull thickness) distances.

What I think OP tries to do:

  • measure distance between sensor and some wall.
  • place fiberglass sheet against wall, effectively lowering the distance by the thickness of that fiberglass.
  • measure distance again.
  • difference is thickness of the sheet.

That's why my question on thickness. If too thin, it's within the margin of error, which is typically 3-5 mm for cheap ultrasound sensors.