Ultrasonic thickness survey

It’s been 12 years, but this 59yo has come around for a repeat condition survey. Ultrasonic thickness measurements (UTM) taken, but you can’t beat an experienced ear and a hammer for checking the thickness of steel hulls. Thin areas give a thin sound and tapping is much quicker than applying couplant, pressing the probe against the hull and noting the reading. The hammer is the best way to find any thin spots and the UTM is then useful to find the thickness.