I have been testing mtns with OHII and I also am getting the class errors for the two ship in the above posts.
I also had a go at getting a good setup so that mtns and OHII can be loaded at career start without having to adjust you mod list.
Removing the harbour mod fixed this. See my mod list:-
Generic Mod Enabler - v2.6.0.157
[C:\Ubisoft\Silent Hunter 5\MODS]
MightyFine Crew Mod 1.2.1 Alt w beards
German U-Boat Crew Language Pack
No Logo Intro Menu_Animation v. 01.00 by AvM
FX_Update_0_0_19_ByTheDarkWraith
IRAI_0_0_32_ByTheDarkWraith
TheDarkWraith_DC_Water_Disturbances_v2_0_SH5
NewUIs_TDC_6_8_0_ByTheDarkWraith
EQuaTool 01.01 by AvM
Trevally Automated Scripts v0.5
Trevally Harbour & Kiel Canal Pilot v2.8
Trevally Scopes 8x5
SH5 sounds Stormy OH FX
Dynamic Environment SH5 Basemod (light) V2.0
NOZAURIO'S SKIN (U-552-Red Devil Emblem) v-1.0.0
SteelViking's Interior Mod V1.2
OPEN HORIZONS II_full v1.6
mtns - more traffic, nations and ships 1_8b
mtns - OHII&HarbourAdditon_Fix_1_6b
mtns - OHII&HarbourAdditon_Fix - restore minefields (optional - activate at last)
Equipment_Upgrades_Fix_v1_4_byTheBeast
This list allows me to use mtns and OHII together with no issues in kiel
