No doubt that a boat is one of the safer places to be during Sit X.
Desalination can be accomplished with water cone devices or the like - www.watercone.com...
Food is bountiful with a bit of preparation, and you need not be a sitting duck - you can lay pots out and check them periodically to supplement your
diet with some tasty crab/lobster.
Rod/reel fishing is not that difficult once you get comfortable with the equipment, or trolling with a net can yield a cornucopia of various edible
critters. The ones you can't eat, you can use as bait. There's still a pretty big need for other staples, things you can't find at sea, like
flour and butter and fruit and nuts and the like, so that would present a problem. Perhaps the best solution to that would be a supply of vitamins or
something to that effect, to supplement your diet and guard against things like scurvy.
Fuel might be a bit of a trick, getting to land, acquiring fuel, and leaving again without incident would be a stroke of luck. Maybe going somewhere
a lot less 'civilized' would be the safest bet. You can carry a good deal of fuel, and if used sparingly I imagine it would last a long time -
especially if it's diesel.
Sailboats are clearly a better choice, since they can reach a respectable speed even without any fuel at all - though I wouldn't personally want a
hoby cat, they're too exposed and flimsy. A lot of fun for just mucking about, don't get me wrong, but if you're living on a boat, a cabin is a
necessity I would think.
I'd love to get one of those ocean freight liners, and fill the hold with all the non-perishables you'd need for twenty years, and enough fuel to go
'round the world a half-dozen times, but such things aren't practical - you need a crew, and talk about a blip on the radar...
That might be a viable solution for a commune, or some organized band of relatively-skilled individuals. If you've got a few talented people, quick
learners and such, you could probably cover all the needs of the ship, and then you'd have a nice, not-so-little floating fortress.
Pirates aren't that big a deal unless you frequent certain places, Indonesia, China, the Ivory Coast, and so on. There are always bound to be more
thugs and thieves on land than at sea anyway because, let's face it, most of those sort have neither the means nor the motivation to take to sea.
The comment about radar is interesting, but I would think it unlikely that in a Sit X, there would be legions of radar operators sitting calmly at
their posts, dispatching coast guard cutters or the like. Those people all have families, etc., and they're just as likely as you are to try and bug
I suppose martial law is a different animal entirely, and in that case, you have to apply some logic, and look at it from the perspective of the
military. They have to expend resources efficiently, and sending a battleship or even a cutter with full crew to go chase a couple of people on a
sailboat is a lousy expenditure of precious resources. They're going to want to concentrate on densely populated urban areas - anyone living in the
deep woods or out at sea could probably go unmolested for 20 years simply because it's not worth anyone's time to go mess with them.
I imagine if you were orchestrating some sort of rebellion, using your boat as a headquarters, that would be a different story...
Generally speaking, a low profile seems to be the key to surviving all these theoretical situations.
Final notes - as has been said, tsunamis wouldn't be a problem, their waves are small when out at sea. Normal waves would be your biggest issue, but
one can usually weather the storms, with a sufficiently sea-worthy vessel and a bit of know-how.
Obviously, the open ocean is a killer if you haven't a clue what you're doing, but becoming familiar with sailing and navigation might be very high
on the list of good skills to develop while you still have the luxury of time.
All in all, your chances of survival aren't great no matter what you choose, and everyone has to go sometime. Maybe it's just me, but I'd rather
go down with the ship, than hiding in a hole somewhere. Personal preference, I suppose.