TM 1.6 has NSM 3.2 light included.
There is a newer version (3.3) which is a lot better. But you must install NSM 3.3 over TM, otherwise you will override the new version with the old one. I reccomend using the classic version, the light version has increased flooding times. There is also a test mission coming with NSM 3.3. Go to Single Player Missions and chose Natural Sinking Mechanics. You can test the mod on different kinds of ships.
The latest version of NSM is here:
http://www.subsim.com/radioroom/showthread.php?t=120269