Yes, a wood boat will float, just at the surface...  Meaning you won't be able to board and bail since the shear line of the gunwales will dip below the waterline.  Trust me, I know what I'm talking about.  The additional flotation is a necessity for safety.  It keeps the boat higher up out of the water by displacing all the water that would be in those compartments if you capsized.  Now the choice of flotation is up to you, whether it's two-part mixed expanding foam, piece of closed cell foam or Opti bags like I have.   

 I am in the process of building a NE Dory as well and lilke you, i think the floation as well as the large black thumscrews do nothing to enhance the beauty of the boat.  And in fact are unsightly.  I just returned from visiting my son and daughter-in-law in Denmark and saw an awlful lot of really pretty dory-type wooden sailboats.  None of them had any floatation.  I trust me it gets pretty windy there.

   I clicked 'post' on the above before I completed my thoughts.  I am definitely going to replace the black thumbscrews with some other means of attachement, but not quite sure yet.  As for floatation, I have thought about opti bags and also modifying the area under the seats/thwarts to be water tight expanding foam as well as in the fore and aft section.  I am not a big fan building a very pretty boat only to hand bumpers or worse, pool noodles over the side.  One might as well just buy one of the many fiberglass sailors that are mass produced if you are going to drape bumpers over it, in my opinion.  I am sure open to suggestions. 

I agree that the black thumbscrews are unsightly. I'm going to do without the ones on the thwart by using brass wood screws instead (like the rest of the thwarts). Not sure what I'll do for the removable mast holder (lug rig), perhaps brass wingnuts or something similar will do.

I am also replacing the black plastic cleats on the mast with brass cleats from CLC. Highly recommended, good price and they look much better.

Still undecided on the floatation. 

I think that the foam is to satisfy a Coast Guard requirement that boat be bailable when swamped. Unless you load it with a V8 engine or something similar it will not sink. If I was using it as just a rowboat, I wouldn't hesitate leaving the foam off (but I'd always wear my PFD, not just have it available). A sailboat is a different issue. For that I'd have some kind of flotation (and wear the PFD).

Be safe,

Laszlo

I'd be willing to settle for temporary floatation, since I do plan to sail the dory. The opti bags are certainly a possibility, assuming you're referring to the bags made by Resail. Then I'd have some waterproof storage as well. How/where did you attach them?

My Opti bags are from Holt (Allen).  I have an Eastport Pram, so they wedge perfectly into the circular cutouts in the center bulkhead beneath the center thwart.  Easy in/out.