Well the read-me says:
submarines:
only external textures used including type II & XXI
different textures used for VIIB & VIIC
corrected all schnorkel masks textures
added seabed repair mod
So im guessing if your ship is a VIIB (as mine is) that the mod wont work for that model---thus the snow-white paintjob including the deck textures and so-on, like i said im guessing...