"Splish": Well it seems to me that this is really a multi part question, and I will be happy to answer the first part.

Fortunately we are now sailing in the new millennium, there are many great boat designs and designers out there, and West Marine’s putting new equipment on their shelves every day. Tools are available that make navigation simpler, safer, and much quicker, not to mention more accuracy beyond the capabilities of sextants and tables. (This is not to say that a good grounding on the skills of navigation is not essential when venturing offshore.) But this does free up more time for handling the ship and getting more rest with less stress.

Now as far as the mechanics of sailing go, the limitations, would seem to be the amount of sail that one person can comfortably handle alone, at least that was the first consideration when the early single handers took to the seas around the turn of the last century. Again in the new millennium we have modern, lightweight, and super strong materials, to build our hulls, our rigs, and our sails. Not to mention electric winches, roller furling headsails and even mainsails. Larger boats are lighter than they used to be and don’t need as much sail area anymore to develop the horse power needed to drive a larger vessel through a big head sea.

All these things make it possible for the seasoned single hander to confidently handle a very large and comfortable boat in almost any conditions.

Single-handed sailors are regularly racing around the world in vessels of 60 feet or more, at speeds that, only a few years ago, the average sailor would never have dreamt possible.

"Splash": And I will be happy to answer part 2 of the question.

Both of us have spent a mass of sailing time at sea, racing off-shore and living aboard. It is my experience, and the experience of many of the live-aboard cruisers that I have met, that “no boat is big enough for guests that often overstay their welcome”. Believe me anything much smaller than an aircraft carrier gets to be a very small space very quickly. For the average cruising couple, a vessel with one very comfortable stateroom, a light and airy salon and galley, and possibly a cabin or two at the other end of the boat that is not so comfortable that your friends/family would want to stay for too long a period. If you do have friends come out for an extended stay, then plan to be in an area that has shore-side accommodation so that your friends can go ashore most evenings and sail with you during the day. This keeps the stress of “living in confined area” down to a minimum.

If you are planning to have guests on board often or for extended periods, you must start thinking of your vessel as a charter boat and not a private sailing yacht!

So how large a vessel can one person handle comfortably?

Well that depends more on the person and his/her skill level than the persons strength. The simple answer is that with good preparation and planning, it’s probably bigger than you think.