max size for solo sailing

[Sailing Moosie]

What is generally the upper end in of a yacht that could be sailed solo?

[sailingfool]

The Open 50s run up to 60'' and are sailed single-hanged around the world.

[SailinJay]

With an electric winch to assist in raising a large main, autohelm to assist as crew while one goes about the normal tasks of sailing, and all sail controls led aft to the cockpit, 50-60-foot boats can be sailed single-handed.

To me the key word here is "sailed." Once out on the water, any boat, with the appropriate equipment, can be sailed by one person. The key is whether you can (1) get away from the dock without assistance or (2) get back in your slip without assistance.