Hi @rmackay9 ,
I use two sensors. One is located on the bow, and the second on the stern(both on bottom).
From the picture I think it is clear how you can understand how I use. For my model, I made hydrostatic curves that help me to load the boat.
After the sensors are initialized, the atmospheric pressure is taken as zero, after the launch of the boat takes place (it was once, the sensors are powered separately and permanently, everything is easier for small boats). Then the pressure is recalculated from the “new zero” and transferred to the depth.
Part of the code for the calculation
if (!digitalRead(13)) {
// we calculate the absolute pressure readings
atT = mBAR * 0.001019716212978;
cmH2O = mBAR * 1.019744288922;
} else {
// we calculate the value of the relative pressure
atT = (mBAR - deltamBAR) * 0.001019716212978;
cmH2O = (mBAR - deltamBAR) * 1.019744288922;
}