yes you can do it in GWX but you have to be absolutely stopped before you do so.
1. dive to within 5 - 10 meters of the seabed
2. Stop the u-boat until the speed indication is zero
3. hit "D"
4. Have a damage control team ready
5. you might take some damage but it will be very light
NOTE! - settling your boat on the sea bed AKA "bottoming the boat" was a real life tactic when all else failed: BUT it is not a recognized tactic in SH3, if you do this, it will make absolutely no difference to the detection criteria of the AI sensors. this is a hard code thing IIRC and there is nothing that can be done about it without Ubisoft releasing the SDK which is not likely to ever happen.
If you find yourself trapped in shallow water... bottoming the boat will not change your detectability. the only way you will decrease the chances of being detected will be to go deep and use other tactics recommended in the GWX manual
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