If you've got a Steam version of the game now, you need to buy a Steam version of the Uboats add-on. If you've got a DVD of the game, you can buy either another DVD or a download from places like Amazon. If you're in the US, you can click on
this link for Uboats and SubSim will get a cut, or just "Search" for Silent Hunter 4 Uboats after clicking on one of the links at
the SubSim Store. The going rate right now is $10US
Now, some folks think me strange, but I have a v1.2 (or is it v1.12???) disk, that I've patched with Ubisoft patches up to v1.4. I still have that on my one computer, and I also purchased a Uboats add-on (like linked to above) to bring it up to v1.5, but I used MultiSH and have a 1.4 and 1.5 install. Then, a couple of years ago, the DVD "Gold" version went on sale, which is the Uboats as part of the disk, and I got it and put it on another computer. So I've got 2 copies of the game. I've got two boys who love to game (well, maybe not the old man's stuff so much), and when I can convince them again that "I swear, I won't sink you, and I won't sink the ships right in front of you..." Now, that is networking fun...