Looks fantastic so far! A great mod for adding the ships weapons as well as helicopters would be the MCHeli mod which has recently been updated to 1.7.10. The mod requires forge and can be found here: http://silvania.co.uk/mods/downloads/mcheli.html The site is in Japanese and a little bit hard to navigate but believe me, the mod is well worth it! Hope you can finish the build soon!

Why does it have a huge hole in the side? That thing would sink within seconds

Like the design, not sure about the name, "Sea" sounds kinda odd compared to "Ocean". Ill try to think of something :P