Frank is right. There are a number of old threads comparing different boats and their capabilities, etc. Now, most of these are opinions - so take them as such. I have owned a Catalina (actually many of them) and have put them in some really bad seas offshore... so it is basic generalities. I would also like to make a statment that most offshore boats are built stronger than most "island hopping" boats... but that does not make them a better boat - IT ALL DEPENDS ON WHAT YOU ARE GOING TO USE IT FOR. I try and scream this to people all the time. Let me tell you why:
One of the more recognized "bluewater" boats is a Valiant. They are very heavy boats and built extremely well. In general, they have smaller and fewer hatches, lots of water, lots of fuel, a small cokpit, and wide cat-walks on the deck. They have a very nice lazarette and a well planned out spot for generators, watermakers, and a lot of the other gear that is required far from shore. Now, that is all great and neccessary if you are punching across seas and to distant shores... but those small hatches dont ventilate as well as a "hatch-filled" boat, those wide cat walks make for a more closed in cabin down below, all that water and fuel eats up space in other parts of the boat, the small cockpits are not great for laying out and spreading out watching the sunsets or entertaining, those nice lazarettes take out living space below... get the picture? The Valiant is a stronger boat and will take a much harder beating than any Catalina or Bene or Hunter... but it would not (is not ) my choice for a island hopper.
Buy a boat for what you are going to use it for primarily. Most passagemakers never leave the first marker... but if I was going to circumnavigate or cross oceans, a Catalina or Hunter or Bene would not be my first choice for the very reasons listed above. Does it mean you cannot do it? No. Does it mean you cannot take a Valiant and Island hop? Of course not. But if you buy the boat for how you will primarily use it, you will be happier, safer, more comfortable, and probably even save a lot of money!