Zo Schtudentz! Ve haff come togezzer anuzzer time for makink mit der boatzlearnink! Vhat's dat? You zay dat your boat hass no top?! Zhat is eet zhould be, mein studentz... for TODAY, ve build ze deckz!
As the professor says, we move on to add decks to our cruisers. This is glorious because it gives us something to do if our ADD strikes while working on internals... you can do superstructure! For the new captains, 'superstructure' is a term that refers to the 'buildings' on top of the deck. WWI ships tend to have much simpler superstructure (abbreviated SS) than do WW2 ships. Most clubs require that the superstructure be in place to battle, although in my experience they will allow a rookie to play without SS a couple of times (or more, in my case), although you may be the target of good-natured ribbing about your 'aircraft carrier' 
Ships look a lot better with their SS, so we will be doing work on that in due time. I will post a simplified drawing to use, or you can figure it out from the plans.
CAUTION: If you have not epoxied your hull together yet... Do so BEFORE doing the decks. The hull needs to be solid before we fit the decks so as not to shift afterwards!
But anyhow, it's time to deck this ship! You will need the 12"x24" sheet of 1/8" plywood that I told you to buy a while back. Some people use 1/8" plastic or whatever comes readily to hand; the key thing is that our subdeck + deck combo must NOT exceed 3/8", and since we used 1/4" ply for the subdeck, that means the deck can't be thicker than 1/8".
Below, you can see that I have placed the 1/8" ply under the back deck, close to one edge of the ply. This is so that we waste as little of the ply as possible. If you used some of the ply for stringers and casement decks, this is important. The ply is pushed all the way up to the step in the deck.
This side view of the above shows the blue foam that I used to hold the ply up against the subdeck for tracing. You can use any material that is readily at hand. With the ply held snugly against the subdeck, trace the outline onto the ply, and cut it out. As before, when cutting, make sure that you are just outside of your line, so that you can sand to fit the subdeck.
Now, the main deck. This is the section that will be removed regularly for rearming and changing batteries. The main deck starts like 8&5/8" from the stern of the ship, and is 24" long (i.e. the length of our plywood!). This is coincidentally long enough to stretch from the SS aft of the step, all the way forward to just behind the forward main turret. Convenient! So I measured up 8&5/8" from the stern, and laid a poop stick across the subdeck there. You can see the cut-out stern deck, next to the hull. 
I measured from several points to ensure that it was square, and made marks on the subdeck at that point. these marks were extended to the SIDES of the subdeck at that 8&5/8" point.
Below, you can see where I have flipped the hull over and set it on the plywood. The white object is a 3x5 card, being used to line up the marks on the sides of the subdeck with the edge of the plywood. Again, try to do this so that the hull is oalong one edge of the ply, but completely ON the ply.
Aaaaaannddd.... TRACE! Make sure that you get the indentions over the casement decks traced! They're hiding under there!
This is what it looks like after tracing the main deck. After this point, cut the main deck out. NOTE: At the stern end, just take the lines straight aft from the step; we'll cut the back end properly soon.
Now, I fit the main deck to the hull, and clamp it on with 4 film clips... Making sure that it lines up well with the hull. I then took small 1/8" scrap pieces from the floor around the saw, and placed them on the underside of the main deck, up against the subdeck, and CA glued them in place. DO NOT use too much CA glue, we only want the scraps to stick to the deck, not the hull! These little bumpers are there to locate the main deck with respect to the subdeck consistently. Note one big one across the back, and 2 smaller ones just forward of that.
Then, up at the front end, I put 2 more bumpers (on diagonal parts this time) to help keep the front located. This actually works pretty well. You can go ahead and make bumpers for the stern deck at this point if you like! The bow and stern deck will be held down with screws, but these bumpers will help keep the wood steady while we drill holes for the screws later.
Repeat this process for the front deck, which should be a really easy task by now 
Zo unteel next time, schtudentz!!! Heil Fluegel!