As sailing ships got larger how did ship builders calculate the amount of sail needed

Just curious how they planned and executed the maximally efficient design and fit out of big sailing ships like Spanish Galleons, English Man O’ Wars and American Clipper ships, in the olden days before sophisticated physics tables and formulas were available?

I’d go for: “Now, how much canvas can I possibly fit on with this rig?”

Actually, that’s a good way to get your extremely expensive capital investment to capsize and be lost with all hands.

I believe the answer would be: a lot of trial and error, experience, and training under Master Shipwrights. But I’d be happy to see a more detailed and informative version of the answer.

The concept of ballast and displacement resisting overturning forces was understood very early, so I would guess they could calculate the potential wind loading and put up as much sail as could possibly be supported.

More interesting to know would be the development of hull design. The shape of the clippers would lead me to believe they know that longer ships could sometime go faster with the same driving force in spite of the larger size, but earlier ships don’t seem to reflect that.

Experience, trial and error, slow evolution from previous experimented designs. Just like pretty muh everything else.

At any rate, “how much?” is the least of the questions and it really does not make much sense. How much cloth a ship can carry depends on the conditions of wind, sea, rig, course, etc. Ships and boats routinely set less than their maximum sail area which is only set when the wind speed is pretty low. As wind speed increases sails begin to be reefed or furled entirely. It is not so much up to the designer but up to the master to know how much sail he can set without endangering the rigging or the ship. The sails and rigging were very flexible and could be varied infinitely. Sails could be reefed or furled. Topmasts could be taken down. etc

More important from the design moment is the type pf rigging: what type of sails and where. Even this was subject to personal preferences and new owners often changed rigs to suit their preferences.

Columbus, on his way to discover new worlds, made a stopover in the Canaries where he changed the mizzen sail of his ship from square to lateen.

Thanks for the info!