Renaming the thread just to make it clear that I was never suggesting "bulkheads OR flotation," but rather the conversation had shifted to whether or not bulkheads are sufficient, or if you need "bulkheads AND flotation."

In my view, it isn't good seamanship to rely on hatch covers to provide buoyancy. Not sure if anyone actually disagrees with the notion that if a fully swamped boat would sink, then it's unsafe - or at least imprudent - to take that boat out on the water without some form of supplemental flotation.

Now, providing enough flotation so that the cockpit coaming stays above water even when you climb up on the deck for re-entry is a lot to ask. But you're presumably already wearing a PFD, so it just needs to stay high enough in the water that you can bail or whatever while floating alongside. Given that the fully-loaded boat (without you aboard) probably weighs significantly less than 100 pounds to start with, and much of that is at a density lower than water, it shouldn't take a whole lot of displacement to make that happen.

So, sure - you can throw some pool noodles into a compartment, or a float bag, or whatever. But seems like those methods are prone to failure - bags can burst or leak, things that can be put into compartments can also be taken out and left ashore. Considering that, and assuming that the actual amount of displacement needed to make the boat safe is pretty small, then it seems reasonable to me to consider ways to permanently incorporate the necessary flotation.

It doesn't have to be foam - I get that foam can absorb water, degrade, mildew, etc., - but then again, so can cedar, right?