The history of naval architecture is fascinating - and varied around the world. I'm going to focus on Europe for this answer, as that's my specialism and it's where a lot of the progress was made in scale modelling for ship design.

We're also going to have a quick detour on defining 'scale model': ship models have been around almost as long as ships, thousands of years, but their potential as a design and training aid wasn't fully realised until relatively recently. 'Hull models' were used to train apprentices and communicate the shape of a vessel to builders as early as the 17th Century, but they weren't used to test designs until much later. They were, however, used to record particularly good designs for later copying and demonstrating new ideas.

It's important to remember that scale modelling didn't replace 'trial and error' design overnight - for a long time modelling was used to train apprentice shipwrights and naval architects while design remained a matter of trial and error - over time pre-build models would become more and more normal. Naval architects would design ship plans on paper before the hull was laid down, but these often only gave the general shape and design of the hull - and left a lot of 'details' down the individual wrights. Eventually, of couse, all ships built would have complex blueprints ('ship plans') produced before anything was laid down.

Starting in the 18th Century European navies began building copies of particularly good ships - a notable example is the French Médée (1740) - which was captured by the British in 1744 (renamed Medea and later Boscawen) and introduced them to the concept of a fast, light, and lightly armoured vessel; and became the guide for the first British 'frigates'. Thee new British frigates would be based partially on Médée and partially on other captured French vessels (including a privateer about which we know little). This was part of a shared British and French practice of copying particularly good British and captured ships, eventually these 'sister ships' would become known as a 'class' named after the progenitor.

Staying with 18th Century Frigates - in 1749 the French navy launched the Forte, followed four years later by clone Égyptienne. These two became known as the 'Forte class', and are notable for being built in different places by different builders - whereas their predeccesors (the Vengeance Class vessels Vengeance and Résistance) were built side by side by the same builder. Interestingly; Forte, Égyptienne, Vengance, and Résistance were all eventually captured by the British and put back into service against their builders - and closely studied to inform future British designs.

Improvements in design practice was incremental - with ship plans getting more detailed and, crucially, being more closely followed as time went on. Initially each man on the slip had a significant degree of agency, and larger ships often had their hull and rigging built in different places (Portsmouth Dockyard, home of the world's first steam pumped drydock and the primary British Navy facility for centuries, actually built very few hulls - but they rigged many, many, warships built nearby) and overseen by different people.

But with industrialisation came standardisation - especially as new devices like steam engines and armour plate were complex and needed to be built to standardised measurements at specalist facilities. But even the world's first class of steam-powered, iron armoured, ocean going warships; the Warrior Class; had their lines based in the earlier wooden Mersey (1858).

Even today naval architects use experience from their own and others' mistakes and successes - even if pre-planned designs and scale modelling allow for faster iteration, it is still iteration.