Comparing SH3 with DW is not the right approach here. SH3's acoustic model is not so accurately designed as to include all the acoustic parameters that DW does. The Uboot's hydrophones will usually pick up contacts near their nominal "range" no matter what. Now, as a SH3 enthousiast myself I would gladly trade some of the aesthetic elements for a more accurate sonar environment and thus make hydrophone usage more fun. This is not to say that SH3 model is completely "flat" but it could sure be improved in terms of sound propagetion depending on SSP, sea state, ownship depth etc. Supposedly being near the surface makes it harder to hear contacts but I have yet to confirm that during play (although I try to convince myself that I have). Of course DW could in turn be improved in terms of ship's behavior on rough seas, masts that are invisible to the enemy etc.
Although both are great games some of their aspects cannot be directly compared so don't feel bad about not getting in DW what you would expect from SH3. Look at it this way: if you manage to master sonar in DW then no british ship will stand a chance against your uboot
