Not nearly so simple as that. Depends on range for one thing.
Yamato - side armour up to 410mm, deck armour 200-230mm
French 380mm gun could theoretically penetrate 270mm of deck armour at 38,000m and 393mm of side armour at 22,000m
All sorts of factors coming into play. Quality of armour, thicker doesn't always mean better. Dispersal of shells, problem for the French until post war. Quality of shells, problem for the French pre 1943. Who gets in the first hits. Damage control. The golden bullet! Perhaps most importantly the French also have a speed advantage so can choose the range they want to fight at.
But the French ships would find it hard to resist Japanese 18.1" shells unless against their deck armour at 20,000 yards.
If you want to lose some days (or weks months!) go check out the gun data over on the NavWeaps site.
[URL unfurl="true"]http://www.navweaps.com/Weapons/index_weapons.php[/URL]
And for one persons take on the "Best Battleship" (be warned there are as many people in the world as opinions about this subject!!!)
[URL unfurl="true"]http://www.combinedfleet.com/baddest.htm#overall[/URL]
The Richelieu doesn't come out of this too badly. Third of 7 as the best all round ship and runner up of 5 in the middleweight category. I must admit to having a soft spot for them.
