Why Joffre was a credible French carrier advance

How good was the French Joffre-class carrier under construction in 1940?

It was a major improvement over Bearn and a credible open-water carrier, although not an ideal Mediterranean design.

Joffre appears much more useful than Bearn as an open-water carrier, with a waterline belt, armoured deck, eight 130 mm guns, and a substantial light anti-aircraft battery. The design is less attractive in the confined and heavily contested Mediterranean. The later doctrine discussion adds an institutional limit: France had only Bearn from which to develop carrier practice, and that experience emphasized reconnaissance rather than a mature strike role. Joffre's better hardware therefore did not automatically provide the French Navy with a fully developed concept for employing it.