Plumper,
Its all a matter of degree. Typical CCA era boats have overhangs totaling 30% to 40% of their waterline lengths. Few modern boats have overhangs that total more than 20% of their waterline length. For what its worth, I am not advocating plumb bows, just short overhangs, but more later.
When you talk about ships, their overhangs rarely exceed 10% of their length but most have overhangs closer to 4% or 5% of their length. But ship's hull forms are shaped by all kinds of factors that are very different than those that shape sail boats, but comparatively speaking, ships have very short overhangs.
Submarines are shaped to to operate efficiently underwater and to leave a minimal turbulence track. On the surface they behave pretty much like preverbial 'submarines' with water flowing very far aft in rough seas, but in any event, again have little to do with sailboat behavior in rough seas.
I did want to comment on your comments: "
The overhang provides a drier ride not a wetter one. It is plumb bowed boats that have a tendency to drive through the waves rather than over them." and
"The point is that as the boat with the shorter waterline length (and consequently higher L/D) gets over run by a wave, the extra boat above the waterline comes into play and lifts the bow up."
People with boats that have long overhangs often say things like that, but its not borne out in tank testing or in observation of actual boats in a seaway. Let me try to use an example to explain why your statement is not particularly accurate.
Visualize two boats with equal deck plans, with equal longitudinal centers of buoyancy and equal displacement forward of max beam, only one has a nearly plumb bow and the other has a long overhang. You can visualize that the near plumb bow would have a straighter finer entry so that it has a gentler collision with the wave.
You can also visualize that as the boats encounter a wave, the entry on the plumb bow would enter the wave and start to increase buoyancy several feet ahead of the long overhang boat, and with the finer bow the buoyancy at the bow would increase in more progressive manner, so that rather than being jerked upward, the plumb bow would have a gentler rise and fall.
And when the bow of the long overhang comes down on the backside of the wave, its blunter shape does so with a greater impact throwing more spray.
I agree that you are right that there are some ill conceived plumb and short bowed modern boats out there where the hull was shaped to create interior volume rather than an efficient sailing shape (Island Packets and Catalina 380's come to mind). By the same token, there are longer overhanged boats that are carefully modeled to be drier and more comfortable underway (Herreshoff's hollow entry boats come to mind).
I also want to comment on
"Proper modern bluewater cruisers still have overhanging bows if for no other reason than to prevent the anchor from flailing the hull and to sweep aside that log that you don't see". If you look at the current clutch of modern offshore cruisers such as the latest Hylas's, Moody's, Hallberg Rasseys or Tayana Annapolis 54, they have have fairly plumb bows for seaworthiness reasons,
anchors are handled otherwise with shortsprits and the like. The extent of overhand found on these boats are not all that disimilar than those employed on such notable offshore working watercraft as the Bristol Channel Pilot Cutters (the originals and not the Hess minature) or the Colin Archer rescue boats.
Respectfully,
Jeff