This will be a dronecraft carrier, Stephen.
You're right, PAR, I failed to read through.
Vallen, dude, you're better off starting way smaller. Find an existing boat you like and get your feet wet before you let your imagination run quite so wild. If you're still wanting to delve into design go to the books portion of this website and order
Preliminary Design of Boats and Ships by Hamlin and/or
Elements of Boat Strength by Dave Gerr.
If all you need is a random platform on the water, pontoon boats have been one of the fastest selling types lately:
https://www.boattest.com/result/?si...Pontoon+Boat&manufacturer_ln=Any+Manufacturer
Or if you don't really intend to go much of anywhere:
http://www.parker-marine.com/sam36page.html
If you're serious about math and proportionality, take a look at:
http://www.boatdesign.net/forums/boat-design/how-wide-should-method-proposed-12440.html
Sometimes it works to decide what engine you want and choose or design a boat appropriate to the engine (esp. if you really are a mechanical engineer).
This video is pretty heavy on the marketing pitch, but I think the engines from the Bombardier Motor Corporation really are interesting, as are the electric motors from the German company Torqeedo. Elco makes electric motors, too, if you'd rather buy American.
If you're really determined to do a larger boat and you want to spec diesel, check out
http://www.steyr-motors.com/marine-diesel-engines/2-4-and-6-cylinder/
Once you've chosen an engine, you might want to download these spreadsheets from a Hawaiian naval architect and work up some numbers:
http://www.hawaii-marine.com/templates/
PVC will deteriorate and become brittle in sunlight. Not the right choice.