One huge disadvantage of sailboats is that one must comply with the firearm/weapon laws of every port one plans to visit. This means in most cases, nothing larger than a pocketknife, and not even flare guns in some jurisdictions.
I would be uncomfortable with this in peacetime. In a SHTF scenario with no coast guards to interdict pirates/smugglers/desperate refugees, I’d consider it suicide.
The alternative is to carry credible weapons in violation of local laws. This is a poor survival tactic. If you are entering, or arriving from, a nation in distress, expect that your boat will be searched.
Also consider that harbors are somewhat limited and very predictable. There are no terrain features to hide behind at sea. Offshore anchorages can be limited and distant. Hijackers have only to wait for your arrival, effectively leaving you besieged at sea, unless you have fuel/food to get to another port without similar problems.
Boats require ongoing expensive maintenance even when not in use, more so than dry land and a sealed retreat do.
The time to use a boat to bugout would be during a predictable slow crash, before things bottomed out, and only to avoid things like airports, aircraft damaged by EMP, etc, or restrictive police and border guards. A boat might offer some less monitored options for escape from such a nation. – Michael Z. Williamson (SurvivalBlog’s Editor at Large )
I would like to point out a few potential negatives that must be considered when looking to bug-out in a sailboat (or any other marine vehicle) that I think were overlooked in the article posted by StudioMan. On the surface it seems like a good idea but I think there are also some major problems with the idea, similar in scale to bugging out in an RV on the land I think, something you yourself advised against doing if I recall.
1. Spare parts/repairs/maintenance. Just like any other vehicle boats will need ongoing and regular maintenance in order to be seaworthy, though potentially less than a trawler or other motorized boat. The average sailboat’s hull is made of fiberglass these days (not simple to repair in the case of damage) and the sails and rigging are no longer made of natural materials as they were hundreds of years ago. In order to just maintain this gear, never mind repair or replace it, scavenging would be required in the event of a catastrophic collapse of society, and at a minimum expensive trade would be required in a soft crash. If the owner of the boat doesn’t have the skills himself to affect the repairs it would make things even more costly or simply impossible and could potentially leave them stranded or worse in a place not of their choosing.
2. Fuel. potentially a minor issue if the owner actually sails the sailboat most of the time, but there will be times when sailing is not the best option and getting underway with power might be more advisable. Engines need fuel, fuel will be expensive or difficult to acquire without exposing oneself to danger on shore.
3. Defense. Yes pirates are, today, restricted to areas of the world easily avoidable by just paying attention to maritime news sources. After a collapse though anyone living by the shore with a boat is a potential pirate, everywhere. The sailboat owner may be able to efficiently travel the globe with little to no fuel use but that is at a very slow pace, the bad guys just need to have enough fuel to shoot out to the sailboat, take what they want, and get back to shore. Today’s Somali pirates successfully ply the waters ranging out to hundreds of miles from shore without any high tech gear, unless the owner keeps to the deep ocean chances are someone will find them at some point, and sailboats do not have the speed to get away. Sailboats in most cases also do not have the capacity to house a sizable crew in order to help repel boarders.
4. One will have to land sometime and local intel will be lacking. For repairs, resupply, scavenging etc eventually one will have to make landfall. Because the sailboat crew is mobile on the boat all landfall will be into what must be treated as hostile territory. Intel will be old at best, nonexistent at worst on the areas where they are forced to stop and will put the crew at risk. Things may look fine but there is no way of knowing that perhaps thirty miles inland a nuclear reactor’s spent fuel rod pool might have burned off a year ago, or the river’s mouth they are currently navigating in might have four or five sewage treatment plants that, due to not being in operation or manned, have been leaking filthy runoff from rain flooded facilities directly into the river for a long time. In the case of a full blown TEOTWAWKI  event I myself would do my best to stay away from any major river or bay myself due to the potential of it being polluted from any number of potentially deadly sources.
5. Potentially the most important point for me: simple survival is a short term goal, long term ‘healthy’ goals should not include perpetual solitude (saying safe out in the deep ocean) or limiting social interactions and responsibilities. Yes, obviously if I was on Long Island in New York and a catastrophic event occurred I would use a boat with my family without much thought as opposed to trying to navigate by land through New York City and the outlying masses of humanity. But I would then simply head to wherever is the next step on my bug-out plan, ditch/hide the boat and be off towards safer areas inland. Outside of an initial survival tool I think the boat would act as a limiter and as a divisive object as far as the goal of finding others and creating a positive social circle. In order for a healthy rebuilding of people’s mental states as well as the state of society children and adults alike will need to learn how to deal with real world problems not how to just run away from them perpetually. Learning this on a well controlled and properly vetted retreat with like minded people would make that goal a bit easier.
Thank you for your time, – I.B.