Try removing Webster's Ship Manuvering Fix for v1.4 and v1.5, and since you have to de-activate them anyway, leave out OMFritzFix (what is that anyway??), SMALLER_SEA_BEAD_ROCKS and SMALLER_SEA_PLANTS_20 and then test. Put the Fritz backin, test, "SMALLER" mods back in, test, etc., and see if you notice a difference in boat handling as you're adding back in. Then you could try Webster's mod again - but that particular mod is for the Stock game, and quite a few of the settings are altered in OM and then DW anyway...
After that, you could try to run the NSS_Uboat9d2.sim file found in Data / Submarine / NSS_Uboat9d2 folder with
Silent 3Ditor. Browse through the various sections and parameters, and tweak away. When you get to the point that you might want to try out what you've altered, use the "File... Save in mod" menu choice, and let S3D create a mini-mod for you. Then activate that, and see what happens. Just remember that most of those settings affect all of the other settings in the file, such that if you change one seemingly unrelated thing, your boat might all of a sudden hit a wave, nose down, and do an uncontrollable dive on you that cannot be stopped
- been there, done that, as they used to say... I don't think they are capable of flying like an airplane, but you never know until you try... lol