Design new rib system and new hulls

Design new rib system and new hulls is an upgrade in Cossacks 3, available at the Academy.

Background
In the heyday of the sailing fleet, the production of wooden hulls achieved perfection. Knowledge stored by carpenters and engineers when building new ships allowed them to construct hulls for the great battleships, the highlight of shipbuilding. Many concepts developed for the building of sailing vessels not only survived up to the epoch of metal ships but were also used in metal shipbuilding.

Effect

 * Enables battleship construction.