I'll have to dig it out and take some pics... but, I think that ... for the conning tower, it is a central column that as you can see is 2 studs wide. The sides are panels attached to either 1x2 technic bricks with two holes and those short pins... and/or 1x4 bricks with the four studs one side. The diving planes are attached with an axle plate attached to a jumper plate/tile.
Great again... but it looks like something easy compared to the rest of your creations. everything's right, for as far as it's finished. build the lower hull too, and you'll get that other smiley you deserve.
For the guy under me u.s. Submarienes only come in one color, BLACK. For blending in with thier suroundings. Any way the lego set itself is great, I like the way you cut it in half to make it look more natral.