there was a post on how to make the changes but I can't find it. I'll try to explain it the best I can.
you will need silent3ditor to make the changes.
first make a copy of Sensors_sub_US.sim found in data/library/USSubParts
open silent3ditor and open your copy of Sensors_sub_US.sim
on the left hand pane click the + next to 46:SensorData
click the 47:SensorData to open the sensor info on the right side pane
You should see SensorType=Hydrophone on the first line of the property tree
click the line that says
MaxSensorHeight=
I think the value for Traveller's Mod was -15.
Under Property Details at the bottom you will see a Value input box. Change the -15 to something like -1 which is what base TMO 2.5 uses.
Do the same thing for SensorData 48/49, 52/53, and 66/67. These are the other types of hydrophones in the game. You can double check that they are hydrophones by verifying SensorType=Hydrophone in the property tree.
Not sure but, I think one of these hydrophones was not an underwater one (the one for the S-Boats) but after these changes I think it will be.
Save the file, make a folder structure for something like MySensors/Data/Library/USSubParts and drop it in your MODS folder and activate with JSGME.
Happy Sailing