rockDawg, a bluewater boat can be anything that the owner wants it to be. I think most of us would argue over the details but we'd all agree a boat was included in the "bluewater" group if:
-It could withstand a rollover with no damage
-It could withstand breaking waves with no damage (and they'll drop with a force of well over a ton per square foot)
-It can maintain steerage in gale+ force winds
-It can sustain the crew safely, if not comfortably, in the same
-It can hold sufficient tankage, food, water, etc. to get the boat across an ocean, figure at least 1000 miles preferably 2000+.
-It is inherently seaworthy, that is, STABLE, both with regard to sailing and balance, and to capsize resistance.
Some of that you can retrofit, some you can't. There are plenty of tales of boats that literally had the cabin sides stove in during heavy storms (mostly pre-fiberglass) and I'd suggest reading "Fastnet, Force 10" and Cole's "Heavy Weather Sailing" for a look at how some hull designs and certain racing rules can make a big difference in what is more or less likely to make a good bluewater boat.
Even the QE2 has taken a beating in heavy wx, but somewhere in between "rogue wave" and "small craft warning" there's a range of typical bad wx to be found in oceans, and a bluewater boat has to be capable of at least dealing with whatever can sneak up on the prudent sailor, in between weathercasts and landfalls.
Oddly enough...an awful lot of abandoned sailboats are eventually recovered after the crew has bailed. A bluewater boat is no good without bluewater crew. "Batteries and crew not included, optional and extra."
"Some people even silicone their portlights shut when they head offshore." Silly people, haven't they ever heard of duct tape?!