I like David_Old_Jersey's thinking, and as I am planning a 10 metre aluminum
junk yawl, it will have two bulkheads fore and aft which will divide the interior
volume into (aprox.) 19%, 60%, and 21% spaces, respectively. The forward bulkhead is too far aft to be called a "collision bulkhead"; these are conventionally no more than 10% of the LWL abaft the cutwater. Any two of the three compartments if unflooded will easily be able to keep her afloat and more or less in trim to either affect a bailout, or make a jury rig and keep moving.
For the smaller boats, Roger Taylor's junk 'Ming Ming' offers some good of advice on WT bulkeads and their relationship to minimalist sailing. He has two books
on this subject, "Ming Ming and the Art of Minimal Ocean Sailing" was published just this year. I am nearly through it, and can recommend it. Its biggest fault is a near lack of detailed drawings of the boat, none on the WT bulheads, nor any interior
plans for that matter. Of course "Ming Ming" is only 23 feet LOA
, so it's almost moot what value they'd have.
Final comment - partial height WT bulkheads may not in practice be better than nothing, other than buying
a little time. The "Titanic" had a lot of them. The motion of a vessel in a seaway will have a tendency to slosh water over the top almost as fast as the water enters the breach in the hull. Additionally, the surge of free-surface water in a sinking boat has enormous power to destroy partial bulkheads that may not be engineered very carefully.