This is how a dry capsize works, if done successfully. The guy will now swing his legs over, stand on the daggerboard, and right the boat.

Once on the centerboard, it's fairly easy to right the boat. This guy is reaching for the jib sheet very close to his hand, which he will hold and lean back (while keeping his feet on the daggerboard).

If the boat "turtles" like this, both people need to get on the hull of the boat and position themselves like these students. This has the advantage that once the boat is about 45 degrees from horizontal, one of the people can crawl on the daggerboard, then later stand to right the boat easily.