So many of these discussions often end up being a 'How long is a piece of thread? type of discussion but I must say that this one has been much richer in its responses than it could have been, and that I feared it might be when it began. I had hoped to respond sooner but work got in the way. Darn!
I have a little different take than perhaps some in this discussion, and come at this from a different direction. As some of you long time readers know, I look at displacement as being a much more relevant determinant of the size of the boat in almost all ways.
When you talk about stepping up in size, the increased cost and labor to purchase and maintain, increased carrying capacity and increased space, are generally proportionate to the increase in displacement more than increased length.
When you talk about ease of single-handing a bigger boat there are a lot of components involved in what makes something 'easy' or hard', which is why you see such different opinions about whether bigger boats are easier or harder to sail. If you sift through the tread above, individual posters have focused on most of these components without necessarily linking them together.
To me, when it comes to deciding how much more difficult it is to handle a bigger boat there are two parts to this, the physical exertion aspect and then the sequencing of the tasks aspect. To me, until you get up to boats big enough to motorize winches
and sail handling gear, the physical exertion required is directly proportional to the boat's displacement. a 10,500 lb 32 footer takes just as much physical strength and effort to sail as 10,500 lb 38 footer (and if of a similar vintage, quality and level of maintainance, equal displacement boats of different lengths will cost roughly the same to buy and roughly the same to maintain.)
Historically, the rule of thumb for offshore cruising boats was ideally 2 1/2 to 5 long tons per person (5,500 to 11,000 lbs per person). Modern equipment has pushed those numbers up some. But for me I find that somewhere around 12,000 lbs is a practical limit for relatively easy single-handing.
When it comes to sequencing the tasks, it gets much harder to say whether a bigger boat is easier or not. Things do happen slower on a bigger boat, but this comes at a price that there is more line
to overhaul, more distance to travel to get around the boat, bigger mechanical advantages and higher losses to friction.
Often it comes down to the gear on board. You can often get by on smaller (lighter) boat with lower grade hardware and less effective hardware layouts. But as a boat becomes bigger, deck plans and hardware quaility become critical to the ease and safety of operation. Because of the longer distances involved, and higher friction and loadings, hardware design and placement becomes critical. Items like cabintop mounted mainsheet travellers , mast mounted halyards and reeflines become very questionable choices as a boat gets longer. Care must be taken to clear the mast and deck of items likely to snag sheets and other running rigging
. If halyards and other control lines
are run aft, as a boat get larger, low friction blocks become necessary throughout the system. Sheet winches
need to be placed near the helmsman so that the helmsman does not have to stand up to make adjustments. and so on.
More on this later....gotta run.