How wooden warships overcame limits on hull length

What could make ships of the line longer instead of adding more gun decks?

Stronger structural techniques, especially diagonal cross-bracing, were required to overcome the material limits of long wooden hulls.

Age-of-sail hull proportions reflect the bending limits of timber structures. Designers gained length when they found better materials or new ways to brace and distribute loads. Diagonal cross-bracing provided an important answer by helping a long hull resist working and sagging. The change was structural rather than a simple choice to stretch an existing multi-deck hull.