Hi Mikhayl, I've taken a look, and it's not a problem at all in the .dat. It's a problem with the texture. The artifacts you see in game are in fact not the ambient occlusion map itself (the AO map is rendered OK!), but the specular map that is rendered. I noticed this immediately because I only saw the artifacts when I moved the cam (iow. the angle vs the sun changed).
Then I looked at the O01 DDS, and there I saw indeed the AO map was also in the alpha channel of the texture, which is wrong. The alpha channel is reserved for the specular map. So, I copied a grayscale version of the T01 map (which is quick-n-dirty, you'd want to make a true specular map) into the alpha channel, and she rendered fine. This is the texture I used:
http://sh4.skwas.net/temp/NSS_Uboat2b_O01.rar
PS: You should also provide the extra mipmaps. You can choose this as an option when saving to DDS.
PS2: The AO map could use a little more detail.
PS3: The specmap uses the same uv-data as the diffuse map.