Oh, what's the word?
At any rate, I haven't seen this one asked: which monohulls are known for staying upright, with little heeling?
I realize this is kind of like asking about trees without leaves, but you get the drift.
It may not be easy to quantify any answer until we know what YOU think that the descriptor "stiff" and "tender" mean.
Lots of beginners, and you may or may not be one, liken it to what happens when they step aboard at the dock.
Different meaning altogether when under sail, though.
Besides looking at a ballast ratio, you gotta look at beam, and the shape of the bilge sections. There are a ton of great-sailing boats that are very stiff after they heel XX number of degrees to their designed sailing angle of heel.
There are also a lot of boats that sail mostly upright until they get over-pressed in stronger winds and then round up quickly after surprising their novice owners with a sudden heel angle of 30+ degrees.
Trick is to know which is which.
I have owned a boat designed to sail at 18 degrees, and occasional visitors thought it tender and tippy when they stepped aboard and felt the movement. Then when the wind piped up they were equally impressed with how little
it heeled beyond that 15 degrees. It had slack bilge sections. It was both very quick in light air due to a narrow DWL and reassuringly stiff
in heavy air albeit at braced-feet-on-the-low-side-seat angles.
Our last two boats have had somewhat more pronounced turns to their bilges and correspondingly somewhat "flatter" bottoms. They move less when one steps aboard. Neither has been overly beamy nor had any difficulty in heavy air, though. By "not overly" the length/beam on them was/is 26'8" X 8'4" and 34' X 10'10". Both are considered a bit narrow by the floating-condo standards of the present.
I doubt that you will find any monohull sail boat that sails completely "upright". And, if you do, it will likely be the result of a very small sail plan, excessive beam, and a heavy hull with firm bilges... and it will be a very slow
If you can, get a ride on a classic Alberg Cape Dory design on a windy afternoon, and then another ride on a similar-length HuntaCataBenaLina for an equally breezy afternoon. This will probably give you some very
useful input. Whichever you like best, for your purposes, is OK
YMMV. Opinions rendered on the hour, deposit .02 please.