Something to add, there is the Mahina list that is floating in a sticky around here. A good list with "THAT" persons minimum list of specs one should shoot for. BUT, if you have 1 gal too little fuel, water, black tankage, you are off the list. You then have to ask yourself, is 1 less gal off shore going to kill you? or 1 more gal going to make you survive? probably not, but the list is still worth taking a gander at.
Another rating to look at, but again, you need to understand the how and what of the ratings, is the European rating system. IE class A, B, C and D rated boats. You can have a B rated boat that is literally a better built boat than an A. BUT, the A is rated for offshore work, as such, it has a designed area for a life raft, scantlings to handle IIRC a force 10 wind vs 8, waves a bit higher etc. You may also see an A8, B10, C12 for a given boat. Off shore is max 8 people, more local is 10, lakes will be max 12 people on board the boat. Another part of this is the most a boat will go to the side before going turtle. An off shore will be say 125 degrees, a more inshore 120 or less. A dinghy IIRC can go turtle on its own per say. You need to look at, and really understand the ratings before saying what is good or bad.......
Older boats say about 10-15 yrs or so old, will not have this rating, as that is about how long it has been in effect. ALtho a different rating system was in place from about 1980 to the initial of this one, after the fastnet race. This was to make sure boats could survive certain issues off shore.
Reality is, just about ANY boat in the 30-32+ foot range will go offshore and be rated per say. THere are smaller ones, Moore 24, Hobie 27, the mini 6.5M boats that go against this generality......
Marty