Many/most (and there are more than a few) J/24 sinking's involve a scenario where the boat is being raced hard in a big breeze with the spin up. The boat broaches, the cockpit lockers open and water pours in there/boat starts to sink/does sink.
Several fixed for that. On mine I have a small carabiner attached to a key float, one for each side/cockpit locker. When conditions merit, I clip the carabiners to the cockpit locker hasp where the lock would go and this prevents them from popping open in the event of a broach (and the key float is if I happen to drop one overboard when bringing out it doesn't go straight to the bottom).
Other suggestions would be in heavy weather to keep the companionway hatch board in/companionway hatch pulled aft. Also less sail area helps, particularly when short handed sailing. As I day sail the boat a fair amount and it is usually just myself and other half, there is not the 4 guys on the rail providing ballast that the boat was designed for. So long story short I had a Dacron #4 built for the boat, slightly smaller than the blade jib and I find that I use it a fair amount/like the sail a lot.
Thank you, Thomas and Vince! I have already adopted the habit of latching the cockpit lockers with stainless, spring-latched carabiners. I had contemplated enclosing certain spaces with foam, but the article is another approach to consider. Good approaches to think about on a cold, wintry day!
Thank you both!