Re: Wood hull -- sealing question?
You need to do a lot more that stick some goo in the seams of an old wooden boat, if you want to protect the boat and make her watertight.
Possibly, and you might need a professional's help to determine the condition of your caulking, you may need to reef out the old caulking (not just the putty, but the cotton and oakum too), put in a layer of oakum, using proper caulking irons, then a layer of cotton, again set with a caulking iron, then the product designed for the job; underwater seam compound.
Unfortunately for all wooden boat owners, the government has outlawed the best products for your situation and none of the fancy new products can hold a candle to just plain red lead paint, as a seam preparation agent. I would use extremely cheap high copper content oil based commercial bottom paint to paint the seams before caulking, but I doubt you'll be allowed, so find any oil based paint that is toxic to toredoes; there must be something available.
I used to make my own seam compound using linseed oil putty, red lead powder, zinc powder and red lead paint, trying to keep the toredoes out of my wood. Once in a while they ate through that toxic mixture, so I've little hope the modern stuff will work at all, but one works with what one has.
"Any idiot can make a boat go; it takes a sailor to stop one." Spike Africa aboard the schooner Wanderer in Sausalito, Ca. 1964.